IPS Josh Tseng Internet Draft Kevin Gibbons Nishan Systems Standards Track Expires November 2002 Franco Travostino Nortel Networks Curt Du Laney IBM Joe Souza Microsoft May 2002 Internet Storage Name Service (iSNS) Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of [RFC2026]. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Acknowledgements Numerous individuals contributed to the creation of this draft through their careful review and submissions of comments and recommendations. We acknowledge the following persons for their technical contributions to this document: Mark Bakke (Cisco), John Hufferd (IBM), Julian Satran (IBM), Kaladhar Voruganti(IBM), Joe Czap (IBM), John Dowdy (IBM), Tom McSweeney (IBM), Jim Hafner (IBM), Chad Gregory (Intel), Yaron Klein (Sanrad), Larry Lamers (SAN Valley), Jack Harwood (EMC), David Black (EMC), David Robinson (Sun), Alan Warwick (Microsoft), Bob Snead (Microsoft), Fa Yoeu (Nishan), Ken Hirata (Vixel), Howard Hall (Pirus), Malikarjun Chadalapaka (HP), Marjorie Krueger (HP), and Vinai Singh (American Megatrends). Gibbons, Tseng, Monia Standards Track [Page 1] Internet Storage Name Service (iSNS) May 2002 Comments Comments should be sent to the IPS mailing list (ips@ece.cmu.edu) or to the authors. Tseng, Gibbons, et al. Standards Track [Page 2] Internet Storage Name Service (iSNS) May 2002 Table of Contents Status of this Memo...................................................1 Acknowledgements......................................................1 Comments..............................................................2 1. Abstract.......................................................7 2. About this Document............................................7 2.1 Conventions Used in this Document..............................7 2.2 Purpose of this Document.......................................7 3. iSNS Overview..................................................7 3.1 iSNS Architectural Components..................................8 3.1.1 iSNS Protocol (iSNSP)..........................................8 3.1.2 iSNS Client....................................................8 3.1.3 iSNS Server....................................................8 3.1.4 iSNS Database..................................................8 3.1.5 iSCSI..........................................................8 3.1.6 iFCP...........................................................9 3.2 iSNS Functional Overview.......................................9 3.2.1 Name Registration Service......................................9 3.2.2 Discovery Domain and Login Control Service (Zoning)............9 3.2.3 State Change Notification Service.............................11 3.2.4 Open Mapping Between Fibre Channel and iSCSI Devices..........11 3.3 iSNS Usage Model..............................................12 3.3.1 iSCSI Initiator...............................................12 3.3.2 iSCSI Target..................................................12 3.3.3 iSCSI-FC Gateway..............................................13 3.3.4 iFCP Gateway..................................................13 3.3.5 Management Station............................................13 3.4 Administratively Controlled iSNS Settings.....................13 3.5 iSNS Server Discovery.........................................14 3.5.1 Service Location Protocol (SLP)...............................14 3.5.2 Dynamic Host Configuration Protocol (DHCP)....................15 3.5.3 iSNS Heartbeat Message........................................15 3.6 iSNS and NAT..................................................15 3.7 Transfer of iSNS Database Records between iSNS Servers........15 3.8 Backup iSNS Servers...........................................17 4. iSNS Object Model.............................................19 4.1 NETWORK ENTITY Object.........................................19 4.2 PORTAL Object.................................................19 4.3 STORAGE NODE Object...........................................19 4.4 FC DEVICE Object..............................................20 4.5 DISCOVERY DOMAIN Object.......................................20 4.6 DISCOVERY DOMAIN SET Object...................................20 4.7 iSNS Database Model...........................................20 5. iSNS Implementation Requirements..............................21 5.1 iSCSI Requirements............................................21 5.1.1 Required Attributes for Support of iSCSI......................21 5.1.2 Example iSCSI Object Model Diagrams...........................22 5.1.3 Required Commands and Response Messages for Support of iSCSI..24 5.2 iFCP Requirements.............................................25 5.2.1 Required Attributes for Support of iFCP.......................25 5.2.2 Example iFCP Object Model Diagram.............................27 5.2.3 Required Commands and Response Messages for Support of iFCP...27 5.3 Use of TCP For iSNS Communication.............................29 Tseng, Gibbons, et al. Standards Track [Page 3] Internet Storage Name Service (iSNS) May 2002 5.4 Use of UDP For iSNS Communication.............................30 6. iSNSP Message Format..........................................30 6.1 iSNSP PDU Header..............................................30 6.1.1 iSNSP Version.................................................30 6.1.2 iSNSP Function ID.............................................31 6.1.3 iSNSP PDU Length..............................................31 6.1.4 iSNSP Flags...................................................31 6.1.5 iSNSP Transaction ID..........................................31 6.1.6 iSNSP Sequence ID.............................................31 6.2 iSNSP Message Segmentation and Reassembly.....................31 6.3 iSNSP Message Payload.........................................32 6.3.1 Attribute Value 4-Byte Alignment..............................32 6.4 iSNSP Response Error Codes....................................32 6.5 iSNS Multicast Message Authentication.........................33 6.6 Registration and Query Messages...............................35 6.6.1 Source Attribute..............................................35 6.6.2 Message Key Attributes........................................36 6.6.3 Delimiter Attribute...........................................36 6.6.4 Operating Attributes..........................................36 6.6.5 Registration and Query Request Message Types..................37 6.7 Response Messages.............................................49 6.7.1 Error Code....................................................49 6.7.2 Message Key Attributes in Response............................50 6.7.3 Delimiter Attribute in Response...............................50 6.7.4 Operating Attributes in Response..............................50 6.7.5 Registration and Query Response Message Types.................50 6.8 Vendor Specific Messages......................................54 7. iSNS Message Attributes.......................................54 7.1 iSNS Attribute Summary........................................54 7.2 Entity Identifier-Keyed Attributes............................57 7.2.1 Entity Identifier (EID).......................................57 7.2.2 Entity Protocol...............................................57 7.2.3 Management IP Address.........................................58 7.2.4 Entity Registration Timestamp.................................58 7.2.5 Protocol Version Range........................................58 7.2.6 Registration Period...........................................58 7.2.7 Entity Index..................................................59 7.2.8 Entity ISAKMP Phase-1 Proposals...............................59 7.2.9 Entity Certificate............................................59 7.3 Portal-Keyed Attributes.......................................60 7.3.1 Portal IP-Address.............................................60 7.3.2 Portal TCP/UDP Port...........................................60 7.3.3 Portal Symbolic Name..........................................60 7.3.4 Entity Status Inquiry Interval................................60 7.3.5 ESI Port......................................................61 7.3.6 Portal Group Tag..............................................61 7.3.7 Portal Index..................................................62 7.3.8 SCN Port......................................................62 7.3.9 Portal Security Bitmap........................................62 7.3.10Portal ISAKMP Phase-1 Proposals...............................62 7.3.11Portal ISAKMP Phase-2 Proposals...............................63 7.3.12Portal Certificate............................................63 7.4 iSCSI Node-Keyed Attributes...................................63 7.4.1 iSCSI Name....................................................63 Tseng, Gibbons, et al. Standards Track [Page 4] Internet Storage Name Service (iSNS) May 2002 7.4.2 iSCSI Node Type...............................................64 7.4.3 iSCSI Node Alias..............................................64 7.4.4 iSCSI Node SCN Bitmap.........................................64 7.4.5 iSCSI Node Index..............................................65 7.4.6 WWNN Token....................................................66 7.4.7 iSCSI AuthMethod..............................................67 7.4.8 iSCSI Node Certificate........................................67 7.5 FC Port Name-Keyed Attributes.................................67 7.5.1 FC Port Name (WWPN)...........................................67 7.5.2 Port ID (FC_ID)...............................................68 7.5.3 FC Port Type..................................................68 7.5.4 Symbolic Port Name............................................68 7.5.5 Fabric Port Name (FWWN).......................................68 7.5.6 Hard Address..................................................68 7.5.7 Port IP Address...............................................68 7.5.8 Class of Service (COS)........................................69 7.5.9 FC-4 Types....................................................69 7.5.10FC-4 Descriptor...............................................69 7.5.11FC-4 Features.................................................69 7.5.12iFCP SCN Bitmap...............................................69 7.5.13Port Role.....................................................70 7.5.14Port Certificate..............................................71 7.6 Node-Keyed Attributes.........................................71 7.6.1 FC Node Name (WWNN)...........................................71 7.6.2 Symbolic Node Name............................................71 7.6.3 Node IP Address...............................................71 7.6.4 Node IPA......................................................71 7.6.5 Node Certificate..............................................71 7.6.6 Proxy iSCSI Name..............................................71 7.7 Other Attributes..............................................72 7.7.1 FC-4 Type Code................................................72 7.7.2 iFCP Switch Name..............................................72 7.7.3 iFCP Transparent Mode Commands................................72 7.8 iSNS Server-Specific Attributes...............................73 7.8.1 iSNS Server Vendor OUI........................................73 7.9 Discovery Domain Registration Attributes......................73 7.9.1 DD Set ID Keyed Attributes....................................73 7.9.2 DD ID Keyed Attributes........................................74 7.10 Vendor-Specific Attributes....................................75 7.10.1Vendor-Specific Server Attributes.............................75 7.10.2Vendor-Specific Entity Attributes.............................76 7.10.3Vendor-Specific Portal Attributes.............................76 7.10.4Vendor-Specific iSCSI Node Attributes.........................76 7.10.5Vendor-Specific FC Port Name Attributes.......................76 7.10.6Vendor-Specific FC Node Name Attributes.......................76 7.10.7Vendor-Specific Discovery Domain Attributes...................76 7.10.8Vendor-Specific Discovery Domain Set Attributes...............76 7.10.9Other Vendor-Specific Attributes..............................76 7.11 Standards-Based Extensions....................................77 8. Security Considerations.......................................77 8.1 iSNS Security Threat Analysis.................................77 8.2 iSNS Security Implementation and Usage Requirements...........77 8.3 Discovering Security Requirements of Peer Devices.............79 8.4 Configuring Security Policies of iFCP/iSCSI Devices...........79 Tseng, Gibbons, et al. Standards Track [Page 5] Internet Storage Name Service (iSNS) May 2002 8.5 Resource Issues...............................................80 8.6 iSNS Interaction with IKE and IPSec...........................80 9. Normative References..........................................81 10. Informative References........................................82 11. Author's Addresses............................................83 Full Copyright Statement.............................................84 Appendix A -- iSNS Examples..........................................85 A.1 iSCSI Initialization Example..................................85 A.1.1 Simple iSCSI Target Registration..............................85 A.1.2 Target Registration and DD Configuration......................86 A.1.3 Initiator Registration and Target Discovery...................87 Tseng, Gibbons, et al. Standards Track [Page 6] Internet Storage Name Service (iSNS) May 2002 1. Abstract This document specifies the iSNS protocol, which is used for interaction between iSNS servers and iSNS clients in order to facilitate automated discovery, management, and configuration of iSCSI and Fibre Channel (FCP) devices on a TCP/IP network. iSNS provides intelligent storage discovery and management services comparable to those found in Fibre Channel networks, allowing a commodity IP network to function in a similar capacity as a storage area network. iSNS also facilitates a seamless integration of IP and Fibre Channel networks, due to its ability to emulate Fibre Channel fabric services, and manage both iSCSI and Fibre Channel devices. iSNS thereby provides value in any storage network comprised of iSCSI devices, Fibre Channel devices, or any combination thereof. 2. About this Document 2.1 Conventions Used in this Document iSNS refers to the framework consisting of the storage network model and associated services. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. All frame formats are in big endian network byte order. All unused fields and bitmaps, including those that are RESERVED, SHOULD be set to zero. 2.2 Purpose of this Document This is a standards track document containing normative text specifying the iSNS Protocol, used by iSCSI and iFCP devices to communicate with the iSNS server. This document focuses on the interaction between iSNS servers and iSNS clients; interactions among multiple authoritative primary iSNS servers are a potential topic for future work. 3. iSNS Overview iSNS facilitates scalable configuration and management of iSCSI and Fibre Channel (FCP) storage devices in an IP network, by providing a set of services comparable to that available in Fibre Channel networks. iSNS thus allows a commodity IP network to function at comparable level of intelligence to a Fibre Channel fabric. iSNS allows the administrator to go beyond a simple device-by-device management model, where each storage device is manually and individually configured with its own list of known initiators and targets. Using the iSNS, each storage device subordinates its discovery and management responsibilities to the iSNS server. The Tseng, Gibbons, et al. Standards Track [Page 7] Internet Storage Name Service (iSNS) May 2002 iSNS server thereby serves as the consolidated configuration point through which management stations can configure and manage the entire storage network, including both iSCSI and Fibre Channel devices. iSNS can be implemented to support iSCSI and/or iFCP protocols as needed; an iSNS implementation MAY provide support for one or both of these protocols as desired by the implementor. Implementation requirements within each of these protocols is further discussed in section 5. Use of iSNS is OPTIONAL for iSCSI, and REQUIRED for iFCP. 3.1 iSNS Architectural Components 3.1.1 iSNS Protocol (iSNSP) The iSNS Protocol (iSNSP) is a flexible and lightweight protocol that specifies how iSNS clients and servers communicate. It is suitable for various platforms, including switches and targets as well as server hosts. 3.1.2 iSNS Client iSNS clients initiate transactions with iSNS servers using the iSNSP. iSNS clients are processes that are co-resident in the storage device, and can register deviceÆs attribute information, download information about other registered clients in a common Discovery Domain (DD), and receive asynchronous notification of topology events that occur in their DD(s). Management stations are a special type of iSNS client that have access to all DDs stored in the iSNS. 3.1.3 iSNS Server iSNS servers respond to iSNS protocol queries and requests, and initiate iSNS protocol State Change Notifications. Properly authenticated information submitted by a registration request is stored in an iSNS database. 3.1.4 iSNS Database The iSNS database is the information repository for the iSNS server(s). It maintains information about iSNS client attributes. A directory-enabled implementation of iSNS may store client attributes in an LDAP directory infrastructure. 3.1.5 iSCSI iSCSI (Internet SCSI) is an encapsulation of SCSI for a new generation of storage devices interconnected with TCP/IP. Tseng, Gibbons, et al. Standards Track [Page 8] Internet Storage Name Service (iSNS) May 2002 3.1.6 iFCP iFCP (Internet FCP) is a gateway-to-gateway protocol designed to interconnect existing Fibre Channel and SCSI devices using TCP/IP. iFCP maps the existing FCP standard and associated Fibre Channel services to TCP/IP. 3.2 iSNS Functional Overview iSNS Protocol registration and query messages are sent by iSNS clients to servers, while notification messages are sent by iSNS servers to iSNS clients. Messages originating at the client are sent to the iSNS server at the well-known iSNS TCP or UDP port number. There are four main functions of the iSNS: 1) A Name Service Providing Storage Resource Discovery 2) Discovery Domain (DD) and Login Control Service 3) State Change Notification Service 4) Open Mapping of Fibre Channel and iSCSI Devices 3.2.1 Name Registration Service The iSNS provides a registration function to allow all entities in a storage network to register and query the iSNS database. Both targets and initiators can register in the iSNS database, as well as query for information about other initiators and targets. This allows, for example, a client initiator to obtain information about target devices from the iSNS server. This service is modeled on the Fibre Channel Generic Services Name Server described in FC-GS-3, with extensions, operating within the context of an IP network. The naming registration service also provides the ability to obtain a network unique Domain ID for iFCP gateways when required. 3.2.2 Discovery Domain and Login Control Service (Zoning) Zoning is an important function in existing Storage Area Networks that allows storage administrators to partition storage assets into more manageable groups for administrative and management purposes. It also provides important storage network isolation capabilities to prevent interaction among incompatible storage and file systems. iSNS provides zoning capability through the Discovery Domain (DD) Service. The Discovery Domain (DD) Service facilitates the partitioning of iSNS client devices into more manageable groupings for administrative and login control purposes. This allows the administrator to limit the login process to the more appropriate subset of targets registered in the iSNS. iSNS clients must be in Tseng, Gibbons, et al. Standards Track [Page 9] Internet Storage Name Service (iSNS) May 2002 at least one common DD in order to obtain information about each other. iSNS clients can be a member of multiple DD's simultaneously. The DD information stored in the iSNS can be used by various enforcement points in the network to configure security and access control policy. For example, a DD-aware switch can block storage initiators from accessing targets that are not in the same DD, even if the initiator somehow obtained address information for a target outside of its DD. Login Control allows targets to subordinate their access control/authorization policy to the iSNS server. The target node or device downloads the list of authorized initiators from the iSNS. Each node or device is uniquely identified by an iSCSI Name or FC Port Name. Only initiators that match the required identification and authentication information provided by the iSNS will be allowed access by that target node or device during session establishment. If spoofing of initiator identities is a concern, the target may use the public key certificate of the authorized initiator, obtained from the iSNS server, to authenticate the initiator. DD's can be managed offline through a separate management workstation using the iSNSP or SNMP. If the target opts to use the Login Control feature of the iSNS, the target subordinates management of access control policy (i.e., the list of initiators allowed to login to that target) to the management workstations that are manipulating information in the iSNS database. If administratively authorized, a target can upload its own Login Control list. This is accomplished using the DDReg message and listing the iSCSI Name of each initiator to be registered in the Target's DD. An implementation MAY decide that newly registered devices that have not explicitly been placed into a DD by the management station are be placed into a "default DD" contained in a "default DDS" whose initial DD Set Status value is "enabled". This makes them visible to other devices in the default DD. Other implementations MAY decide that they are registered with no DD, making them inaccessible to source-scoped iSNSP messages. If used, the DD_ID of the "default DD" is 1, and the DDS_ID of the "default DDS" is 1. The iSNS server uses the SOURCE field of each iSNSP message to determine the source of the request and scope the operation to the set of Discovery Domains that the iSNS client is a member of. In addition, the Node Type (specified in the iFCP or iSCSI Node Type bitmap field) may also be used to determine authorization for the specified iSNS operation. For example, only control nodes are authorized to create or delete discovery domains. Valid and active Discovery Domains (DD's) belong to at least one active Discovery Domain Sets (DDS's). Discovery Domains that do not belong to an activated DDS are not enabled. Tseng, Gibbons, et al. Standards Track [Page 10] Internet Storage Name Service (iSNS) May 2002 3.2.3 State Change Notification Service The State Change Notification (SCN) service allows the iSNS Server to issue notifications about network events that affect the operational state of iSNS clients. The iSNS client has the ability to register for these notifications of events detected by the iSNS Server. There are two types of SCN registrations: Regular registrations and a management registrations; management registrations result in management SCN's, while regular registrations result in regular SCN's. The type of registration and SCN message is indicated in the SCN bitmap (see sections 7.4.4 and 7.5.12). A regular SCN registration indicates that the Discovery Domain Service shall be used to control the distribution of SCN messages. Receipt of regular SCN's is limited to the discovery domains in which the SCN-triggering event takes place. Regular SCN's do not contain information about discovery domains. A management SCN registration can only by conducted by control nodes. Management SCN's resulting from management registrations are not bound by the Discovery Domain service. Authorization to conduct management SCN registrations may be administratively controlled. The iSNS server may refuse SCN service by returning a SCN Registration Rejected (error code 17). The rejection might occur in situations where the network size or current number of SCN registrations, has passed an implementation-specific threshold. A client not allowed to register for SCNs may decide to monitor its sessions with other storage devices directly. The specific notification mechanism by which the iSNS server learns of the events that trigger SCN's is implementation-specific, but can include examples such as explicit notification messages from an iSNS client to the iSNS server, or a hardware interrupt to a switch- hosted iSNS server as a result of link failure. 3.2.4 Open Mapping Between Fibre Channel and iSCSI Devices The iSNS database stores naming and discovery information about both Fibre Channel and iSCSI devices. This allows the iSNS server to store mappings of a Fibre Channel device to a proxy iSCSI device "image" in the IP network. Similarly, mappings of an iSCSI device to a "proxy WWN" can be stored under the WWNN Token field for that that iSCSI device. Furthermore, through use of iSCSI-FC gateways, Fibre Channel-aware management stations can interact with the iSNS server to retrieve information about Fibre Channel devices, and use this information to manage Fibre Channel devices as well as iSCSI devices. This allows management functions such as Discovery Domains and State Change Notifications to be seamlessly applied for both iSCSI and Fibre Tseng, Gibbons, et al. Standards Track [Page 11] Internet Storage Name Service (iSNS) May 2002 Channel devices, facilitating integration of IP networks with Fibre Channel devices and fabrics. Note that Fibre Channel attributes are stored as iFCP attributes, and the ability to store this information in the iSNS server is useful even if the iFCP protocol is not implemented. In particular, tag 101 can be used to store a "Proxy iSCSI Name" for Fibre Channel devices registered in the iSNS server. This field is used to associate the FC device with an iSCSI registration entry that is used for the Fibre Channel device to communicate with iSCSI devices in the IP network. Conversely, tag 37 (see section 7.1) contains an WWNN Token field, which can be used to store an FC Node Name (WWNN) value used by iSCSI-FC gateways to represent an iSCSI device in the Fibre Channel domain. By storing the mapping between Fibre Channel and iSCSI devices in the iSNS server, this information becomes open to any authorized iSNS client wishing to retrieve and use this information. In many cases, this provides advantages over storing this information internally within an iSCSI-FC gateway, where the mapping is inaccessible to other devices except by proprietary mechanisms. 3.3 iSNS Usage Model The following is a high-level description of how each type of device in a storage network can utilize iSNS. Each type of device interacts with the iSNS server as an iSNS client, and must register itself in the iSNS database in order to access services provided by the iSNS. 3.3.1 iSCSI Initiator An iSCSI initiator will query the iSNS server to discover the presence and location of iSCSI target devices. It may also request state change notifications (SCN's) so that it can be notified of new targets that appear on the network after the initial bootup and discovery. SCN's can also inform the iSCSI initiator of targets that are removed or no longer available in the storage network, so that incomplete storage sessions can be gracefully terminated and resources for non-existent targets can be reallocated. 3.3.2 iSCSI Target An iSCSI target allows itself to be discovered by iSCSI initiators by registering its presence in the iSNS server. It may also register for SCN's in order to detect the addition or removal of initiators for resource allocation purposes. The iSCSI target device may also register for Entity Status Enquiry (ESI) messages, which allow the iSNS to monitor the target device's availability in the storage network. Tseng, Gibbons, et al. Standards Track [Page 12] Internet Storage Name Service (iSNS) May 2002 3.3.3 iSCSI-FC Gateway An iSCSI-FC Gateway bridges devices in a Fibre Channel network to an iSCSI/IP network. It may use the iSNS store FC device attributes discovered in the FC name server, as well as mappings of FC device identifiers to iSCSI device identifiers. iSNS has the capability to store all attributes of both iSCSI and Fibre Channel devices; iSCSI devices are managed through direct interaction using iSNS, while FC devices can be indirectly managed through iSNS interactions with the iSCSI-FC gateway. This allows both iSCSI and Fibre Channel devices to be managed in a seamless management framework. 3.3.4 iFCP Gateway An iFCP Gateway uses iSNS to emulate the services provided by a Fibre Channel name server for FC devices in its gateway region. iSNS provides basic discovery and zoning configuration information to be enforced by the iFCP gateway. When queried, iSNS returns information on the N_Port network address used to establish iFCP sessions between FC devices supported by iFCP gateways. 3.3.5 Management Station A Management Station uses iSNS to monitor storage devices and enable or disable storage sessions by configuring discovery domains. A Management Station usually interacts with the iSNS server as a control node endowed with access to all iSNS database records and special privileges to configure discovery domains. Through manipulation of discovery domains, the Management Station controls the establishment and termination of storage sessions in the storage network. 3.4 Administratively Controlled iSNS Settings Some important operational settings for the iSNS server are configured using administrative means, such as through a configuration file, console port, SNMP, or other implementation- specific method. These administratively controlled settings cannot be configured using the iSNS Protocol. The following is a list of parameters that are administratively controlled for the iSNS server. Tseng, Gibbons, et al. Standards Track [Page 13] Internet Storage Name Service (iSNS) May 2002 Setting Default Setting ------- --------------- ESI Non-Response Threshold 3 Default DD/DDS disabled DD/DDS Modification - SNMP enabled - Control Node enabled - Target iSCSI Node disabled - Initiator iSCSI Node disabled - Target iFCP Port disabled - Initiator iFCP Port disabled Management SCN for Control Node enabled Authorized Control Nodes N/A ESI Non-Response Threshold - determines the number of ESI messages sent without receiving a response before the entity is deregistered from the iSNS database. Default DD/DDS - determines whether a newly registered device not explicitly placed into a discovery domain (DD) and discovery domain set (DDS) is placed into a default DD/DDS. DD/DDS Modification - determines whether the specified type of node or protocol is allowed to add, delete or update DD's and DDS's. Management SCN for Control Node - determines whether a registered control node is permitted to register for Management SCN's. Authorized Control Nodes - a list of nodes identified by iSCSI Name or FC Port Name WWPN that are authorized to register as control nodes. 3.5 iSNS Server Discovery 3.5.1 Service Location Protocol (SLP) The Service Location Protocol (SLP) provides a flexible and scalable framework for providing hosts with access to information about the existence, location, and configuration of networked services, including the iSNS server. SLP can be used by iSNS clients to discover the IP address or FQDN of the iSNS server. To implement discovery through SLP, a Service Agent (SA) should be cohosted in the iSNS server, and a User Agent (UA) should be in each iSNS client. Each client multicasts a discovery message requesting the IP address of the iSNS server(s). The SA responds to this request. Optionally, the location of the iSNS server can be stored in the SLP Directory Agent (DA). Note that a complete description and specification of SLP can be found in [RFC2608], and is beyond the scope of this document. Additional details on use of SLP to discover the iSNS server can be found in [iSCSI-SLP]. Tseng, Gibbons, et al. Standards Track [Page 14] Internet Storage Name Service (iSNS) May 2002 3.5.2 Dynamic Host Configuration Protocol (DHCP) The IP address of the iSNS server can be stored in a DHCP server to be downloaded by iSNS clients using a DHCP option. The DHCP option number to be used for distributing the iSNS server location is <>. 3.5.3 iSNS Heartbeat Message The iSNS heartbeat message is described in section 6.6.5.14. It allows iSNS clients within the broadcast or multicast domain of the iSNS server to discover the location of the active iSNS server and any backup servers. 3.6 iSNS and NAT The existence of NAT will have an impact upon information retrieved from the iSNS server. If the iSNS client exists in a different addressing domain than the iSNS server, then IP address information stored in the iSNS server may not be correct when interpreted in the domain of the iSNS client. There are several possible approaches to allow operation of iSNS within a NAT network. The first approach is to require use of the canonical TCP port number by both targets and initiators when addressing targets across a NAT boundary, and for the iSNS client to not query for nominal IP addresses. Rather, the iSNS client initiator queries for the DNS Fully Qualified Domain Name stored in the Entity Identifier field, when seeking addressing information. Once retrieved, the DNS name can be interpreted in each address domain and mapped to the appropriate IP address by local DNS servers. A second approach is to deploy a distributed network of iSNS servers. Local iSNS servers are deployed inside and outside NAT boundaries, with each local server storing relevant IP addresses for their respective NAT domains. Updates among the network of decentralized, local iSNS servers are handled using LDAP and using appropriate NAT translation rules implemented within the update mechanism in each server. The final alternative is to simply disallow use of NAT in communication between the iSNS server and any iSNS client. 3.7 Transfer of iSNS Database Records between iSNS Servers Transfer of iSNS database records between iSNS servers has important applications, including the following: 1) An independent organization needs to transfer storage information to a different organization. Each organization independently maintains its own iSNS infrastructure. To facilitate discovery of storage assets of the peer organization using IP, iSNS database records can be transferred between authoritative iSNS Tseng, Gibbons, et al. Standards Track [Page 15] Internet Storage Name Service (iSNS) May 2002 servers from each organization. This allows storage sessions to be established directly between devices residing in each organization's storage network infrastructure over a common IP network. 2) Multiple iSNS servers are desired for redundancy. Backup servers need to maintain copies of the primary server's dynamically changing database. To support the above applications, information in an iSNS server can be distributed to other iSNS servers either using the iSNS protocol, or through out-of-band mechanisms using non-iSNS protocols. The following examples illustrate possible methods to transfer data records between iSNS servers. In the first example, a back-end LDAP information base is used to support the iSNS server, and the data is transferred using the LDAP protocol. Once the record transfer of the remote device is completed, it becomes visible and accessible to local devices using the local iSNS server. This allows local devices to establish sessions with remote devices (provided firewall boundaries can be negotiated). +-------------------------+ +-------------------------+ |+------+ iSNSP | | iSNSP +-----+ | ||dev A |<----->+------+ | | +------+<----->|dev C| | |+------+ | | | | | | +-----+ | |+------+ iSNSP |local | | | |remote| iSNSP +-----+ | ||dev B |<----->| iSNS | | | | iSNS |<----->|dev D| | |+------+ |server| | | |server| +-----+ | |........ +--+---+ | WAN | +---+--+ | |.dev C'. | | Link | | | |........ | ============= | | | | | | | | | +--+---+ | | +---+--+ | | | local|<--- <--- <--- <-|remote| | | | LDAP | | LDAP: | | LDAP | | | +------+ Xfer "dev C"| +------+ | +-------------------------+ +-------------------------+ Enterprise Enterprise Network A Network B In the above diagram, two business partners wish to share storage "dev C". Using LDAP, the record for "dev C" can be transfered from Network B to Network A. Once accessible to the local iSNS server in Network A, local devices A and B can now discover and connect to "dev C". Tseng, Gibbons, et al. Standards Track [Page 16] Internet Storage Name Service (iSNS) May 2002 +-------------------------+ +-------------------------+ |+------+ iSNSP | | iSNSP +-----+ | ||dev A |<----->+------+ | | +------+<----->|dev C| | |+------+ | | | | | | +-----+ | |+------+ iSNSP |local | | | |remote| iSNSP +-----+ | ||dev B |<----->| iSNS | | | | iSNS |<----->|dev D| | |+------+ |server| | | |server| +-----+ | |........ +------+ | WAN | +---+--+ | |.dev C'. ^ | Link | | | |........ | ============= v | | | | | |SNMP | | | | | | | | +--+----+ | | v | | | SNMP |<--- <--- <--- <---- | | | Mgmt | | SNMP: Xfer "dev C" | | |Station| | | | | +-------+ | | | +-------------------------+ +-------------------------+ Enterprise Enterprise Network A Network B The above diagram illustrates a second example of how iSNS records can be shared. This method uses an SNMP-based management station to manually download the desired record for "dev C", and then directly upload it to the local iSNS server. Once the record is transferred to the local iSNS server in Network A, "dev C" becomes visible and accessible (provided firewall boundaries can be negotiated) to other devices in Network A. Other methods, including proprietary protocols, can be used to transfer device records between iSNS servers. Further discussion and explanation of these methodologies is beyond the scope of this document. 3.8 Backup iSNS Servers This section offers a broad framework for implementation and deployment of iSNS backup servers. Server failover and recovery are topics of continuing research and adequate resolution of issues such as split brain and primary server selection is dependent on the specific implementation requirements and deployment needs. Therefore, it is beyond the scope of this specification to facilitate more than a basic interoperability among failover mechanisms. Further development of redundant iSNS server mechanisms are left to the individual implementation. Multiple iSNS servers can be used to provide redundancy in the event that the active iSNS server fails or is removed from the network. The methods described in section 3.7 above can be used to transfer name server records to backup iSNS servers. Each backup server maintains a redundant copy of the name server database found in the primary iSNS server, and can respond to iSNS protocol messages in the same way as the active server. Each backup server SHOULD Tseng, Gibbons, et al. Standards Track [Page 17] Internet Storage Name Service (iSNS) May 2002 monitor the health and status of the active iSNS server, including checking to make sure its own database is synchronized with the active server's database. How each backup server accomplishes this is implementation-dependent, and may (or may not) include using the iSNS protocol. If the iSNS protocol is used, then the backup server MAY register itself in the active server's iSNS database as a control node, allowing it to receive state change notifications. Generally, the administrator or some automated election process is responsible for initial and subsequent designation of the primary server and each backup server. A maximum of one backup iSNS server SHALL exist at any individual IP address. In addition to proprietary vendor-specific ways of deploying multiple redundant iSNS servers, the iSNS heartbeat can also be used to coordinate designation and selection of primary and backup iSNS servers. Each backup server should note its relative precedence in the active server's list of backup servers. If not already known, each backup server MAY learn its precedence from the iSNS heartbeat message, by noting the position of its IP address in the ordered list of backup server IP addresses. For example, if it is the first backup listed in the heartbeat message, then its backup precedence is 1. If it is the third backup server listed, then its backup precedence is 3. If a backup server establishes that it has lost connectivity to the active server and other backup servers of higher precedence, then it shall assume that it is the active server. The method of determining whether connectivity has been lost is implementation- specific. One possible approach is to assume that if the backup server does not receive iSNS hearbeat messages for a period of time, then connectivity to the active server has been lost. Alternately, the backup server may establish TCP connections to the active server and other backup servers, and loss of connectivity determined through non-response to periodic echo messages (using iSNSP, SNMP, or other protocols). When a backup server becomes the active server, it shall assume all active server responsibilities, including (if used) transmission of the iSNS heartbeat message. If transmitting the iSNS heartbeat, the backup server replaces the active Server IP Address and TCP/UDP Port entries with its own IP address and TCP/UDP Port, and begins incrementing the counter field from the last known value from the previously-active iSNS server. However, it MUST NOT change the original ordered list of backup server IP Address and TCP/UDP Port entries. If the primary backup server or other higher-precedence backup server returns, then the existing active server is responsible for ensuring that the new active server's database is up-to-date before demoting itself to its original status as backup. Tseng, Gibbons, et al. Standards Track [Page 18] Internet Storage Name Service (iSNS) May 2002 4. iSNS Object Model iSNS provides the framework for the registration, discovery, and management of iSCSI devices and Fibre Channel-based devices (using iFCP). This architecture framework provides elements needed to describe various storage device objects and attributes that may exist on an IP storage network. Objects defined in this architecture framework include NETWORK ENTITY, PORTAL, STORAGE NODE, FC DEVICE, DEVICE DISCOVERY DOMAIN, and DISCOVERY DOMAIN SET. Each of these objects are described in greater detail in the following sections. 4.1 NETWORK ENTITY Object The NETWORK ENTITY object is a container of STORAGE NODE objects and PORTAL objects. It represents the infrastructure supporting access to a unique set of one or more STORAGE NODEs. All STORAGE NODEs and PORTALs contained within a single NETWORK ENTITY object operate as a logical unit. Note that it is possible for a single physical device or gateway to be represented by more than one logical Network Entity in the iSNS database. For example, one of the storage nodes on a physical device may be accessible from only a subset of the network interfaces (i.e., portals) available on that device. In this case, a logical network entity (i.e., a "shadow entity") is created and used to contain the portals and storage nodes that can operate cooperatively. No object (portals, storage nodes, etc...) can be contained by more than one logical Network Entity. Similarly, it is possible for a logical Network Entity to be supported by more than one physical device or gateway. For example, multiple FC-iSCSI gateways may be used to bridge FC devices in a single Fibre Channel network. The multiple gateways collectively can be used to support a single logical NETWORK ENTITY that is used to contain all of the devices in that Fibre Channel network. 4.2 PORTAL Object The PORTAL object is an interface through which access to any STORAGE NODE within the NETWORK ENTITY can be obtained. An IP address and TCP/UDP Port number uniquely distinguish a PORTAL object. A NETWORK ENTITY should have one or more PORTALs, each of which is usable by STORAGE NODEs contained in that NETWORK ENTITY to gain access to, or be accessible from, the IP network. 4.3 STORAGE NODE Object The STORAGE NODE object is the logical endpoint of an iSCSI or iFCP session. In iFCP, the session endpoint is represented by the World Wide Port Name (WWPN). In iSCSI, the session endpoint is represented by the iSCSI Name of the device. Tseng, Gibbons, et al. Standards Track [Page 19] Internet Storage Name Service (iSNS) May 2002 4.4 FC DEVICE Object The FC DEVICE represents the Fibre Channel end node. This object contains information that may be useful in the management of the Fibre Channel device. 4.5 DISCOVERY DOMAIN Object DISCOVERY DOMAINS (DD) are a security and management mechanism used to administer access and connectivity to storage devices. Discovery Domains limit the discovery process to the administrator-configured subset of relevant storage devices, preventing initiators from inappropriately attempting login to devices that they shouldnÆt have access to. A query by an iSNS client SHOULD only return information about objects with which it shares at least one active DD. A DD is considered active if it a member of at least one active DD Set. DD's that are not members of at least one enabled DDS are considered disabled. A STORAGE NODE can be a member of one or more DD's. 4.6 DISCOVERY DOMAIN SET Object The DISCOVERY DOMAIN SET (DDS) is a container object for DDÆs. DDSÆs may contain one or more DDÆs. Similarly, each DD can be a member of one or more DDSÆs. DDSÆs are a mechanism to store coordinated sets of DD mappings in the iSNS server. Active DD's are members of at least one active DD Set. DDS's are enabled by setting bit 0 in the DDS Status Field. 4.7 iSNS Database Model The following shows the various objects described above and their relationship to each other. +--------------+ +-----------+ | NETWORK |1 *| | | ENTITY |----| PORTAL | | | | | +--------------+ +-----------+ | 1 | | | * +-----------+ +--------------+ +-----------+ +-----------+ | FC |1 *| STORAGE |* *| DISCOVERY |* *| DISCOVERY | | DEVICE |----| NODE |----| DOMAIN |----| DOMAIN | | | | | | | | SET | +-----------+ +--------------+ +-----------+ +-----------+ * represents 0 to many possible relationships Tseng, Gibbons, et al. Standards Track [Page 20] Internet Storage Name Service (iSNS) May 2002 5. iSNS Implementation Requirements This section details specific requirements for support of each of these IP storage protocols. Implementation requirements for security are described in section 8. 5.1 iSCSI Requirements Use of iSNS in support of iSCSI is OPTIONAL. iSCSI devices MAY be manually configured with the iSCSI Name and IP address of peer devices, without the aid or intervention of iSNS. iSCSI devices also may use SLP [RFC 2608] to discover peer iSCSI devices. However, iSNS is useful for scaling a storage network to a larger number of iSCSI devices. 5.1.1 Required Attributes for Support of iSCSI The following attributes are available to support iSCSI. Attributes indicated in the REQUIRED TO IMPLEMENT column MUST be supported by an iSNS server used to support iSCSI. Attributes indicated in the REQUIRED TO USE column MUST be supported by an iSCSI device that elects to use the iSNS. A more detailed description of each attribute is found in section 7. Tseng, Gibbons, et al. Standards Track [Page 21] Internet Storage Name Service (iSNS) May 2002 REQUIRED REQUIRED Object Attribute to Implement to Use ------ --------- ------------ -------- NETWORK ENTITY Entity Identifier * * Entity Protocol * * Management IP Address Timestamp * Protocol Version Range * Registration Period * Entity Index * Entity IKE Phase-1 Proposal Entity Certificate PORTAL IP Address * * TCP/UDP Port * * Portal Symbolic Name * ESI Interval * ESI Port * Portal Group Tag * Portal Index * SCN Port * Portal Security Bitmap * Portal IKE Phase-1 Proposal Portal IKE Phase-2 Proposal Portal Certificate STORAGE NODE iSCSI Name * * iSCSI Node Type * * Alias * iSCSI SCN Bitmap * iSCSI Node Index * WWNN Token iSCSI AuthMethod iSCSI Node Certificate DISCOVERY DOMAIN DD ID * * DD Symbolic Name * DD iSCSI Node Index * DD iSCSI Node Member * DD Features * DISCOVERY DOMAIN DDS Identifier * SET DDS Symbolic Name * Status * DDS Member * All iSCSI user-specified and vendor-specified attributes are optional to implement and use. 5.1.2 Example iSCSI Object Model Diagrams The following diagram models how a simple iSCSI-based initiator and target is represented using database objects stored in the iSNS Tseng, Gibbons, et al. Standards Track [Page 22] Internet Storage Name Service (iSNS) May 2002 server. In this implementation, each target and initiator is attached to a single PORTAL. +----------------------------------------------------------------+ | IP Network | +------------+--------------------------------------+------------+ | | | | +-----+------+------+-----+ +-----+------+------+-----+ | | PORTAL | | | | PORTAL | | | | -IP Addr 1 | | | | -IP Addr 2 | | | | -TCP Port 1 | | | | -TCP Port 2 | | | +-----+ +-----+ | | +-----+ +-----+ | | | | | | | | | | | | | | | | | | +--------+ +--------+ | | +-------+ +--------+ | | | | | | | | | | | STORAGE NODE | | | | STORAGE NODE | | | | -iSCSI Name | | | | -iSCSI Name | | | | -Alias: "server1"| | | | -Alias: "disk1"| | | | -Type: initiator | | | | -Type: target | | | | | | | | | | | +-------------------+ | | +------------------+ | | | | | | NETWORK ENTITY | | NETWORK ENTITY | | -Entity ID (FQDN): | | -Entity ID (FQDN): | | "strg1.foo.com" | | "strg2.bar.com" | | -Protocol: iSCSI | | -Protocol: iSCSI | | | | | +-------------------------+ +-------------------------+ The object model can be expanded to describe more complex devices, such as an iSCSI device with more than one storage controller, each controller accessible through any of multiple PORTAL interfaces. The storage controllers on this device can be accessed through alternate PORTAL interfaces, if any original interface should fail. The following diagram describes such a device: Tseng, Gibbons, et al. Standards Track [Page 23] Internet Storage Name Service (iSNS) May 2002 +---------------------------------------------------------------+ | IP Network | +-------------------+-----------------------+-------------------+ | | | | +------------+------+------+---------+------+------+------------+ | | PORTAL | | PORTAL | | | | -IP Addr 1 | | -IP Addr 2 | | | | -TCP Port 1 | | -TCP Port 2 | | | +-----+ +-----+ +-----+ +-----+ | | | | | | | | +---------------+ +---------------------+ +---------------+ | | +-------+ +----------------+ +-------------------+ +------+ | | | | | | | | | | +-------+ +-------+ +------+ +--------+ +--------+ +------+ | | | | | | | | | | | STORAGE NODE | | STORAGE NODE | | STORAGE NODE | | | | -iSCSI Name 1 | | -iSCSI Name 2 | | -iSCSI Name 3 | | | | -Alias: "disk1"| | -Alias: "disk2"| | -Alias: "disk3"| | | | -Type: target | | -Type: target | | -Type: target | | | | | | | | | | | +-----------------+ +-----------------+ +-----------------+ | | | | NETWORK ENTITY | | -Entity ID (FQDN): "dev1.foo.com" | | -Protocol: iSCSI | | | +---------------------------------------------------------------+ 5.1.3 Required Commands and Response Messages for Support of iSCSI The following iSNSP messages and responses are available in support of iSCSI. Messages indicated in the REQUIRED TO IMPLEMENT column MUST be implemented in iSNS servers used for iSCSI devices. Messages indicated in the REQUIRED TO USE column must be implemented in iSCSI devices that elect to use the iSNS server. REQUIRED TO: Message Description Abbreviation Func_ID Implement Use ------------------- ------------ ------- --------- --- Register Dev Attr Req RegDevAttr 0x0001 * * Dev Attr Query Request DevAttrQry 0x0002 * * Dev Get Next Request DevGetNext 0x0003 * Deregister Dev Request DeregDev 0x0004 * * SCN Register Request SCNReg 0x0005 * SCN Deregister Request SCNDereg 0x0006 * SCN Event SCNEvent 0x0007 * State Change Notification SCN 0x0008 * DD Register DDReg 0x0009 * * DD Deregister DDDereg 0x000A * * DDS Register DDSReg 0x000B * * DDS Deregister DDSDereg 0x000C * * Entity Status Inquiry ESI 0x000D * Tseng, Gibbons, et al. Standards Track [Page 24] Internet Storage Name Service (iSNS) May 2002 Name Service Heartbeat Heartbeat 0x000E NOT USED 0x000F-0x0013 RESERVED 0x0014-0x00FF Vendor Specific 0x0100-0x01FF RESERVED 0x0200-0x8000 The following are iSNSP response messages used in support of iSCSI: REQUIRED TO: Response Message Desc Abbreviation Func_ID Implement Use --------------------- ------------ ------- --------- --- Register Dev Attr Rsp RegDevRsp 0x8001 * * Dev Attr Query Rsp DevAttrQryRsp 0x8002 * * Dev Get Next Rsp DevGetNextRsp 0x8003 * Deregister Dev Rsp DeregDevRsp 0x8004 * * SCN Register Rsp SCNRegRsp 0x8005 * SCN Deregister Rsp SCNDeregRsp 0x8006 * SCN Event Rsp SCNEventRsp 0x8007 * SCN Response SCNRsp 0x8008 * DD Register Rsp DDRegRsp 0x8009 * * DD Deregister Rsp DDDeregRsp 0x800A * * DDS Register Rsp DDSRegRsp 0x800B * * DDS Deregister Rsp DDSDeregRsp 0x800C * * Entity Stat Inquiry Rsp ESIRsp 0x800D * NOT USED 0x800E-0x8013 RESERVED 0x8014-0x80FF Vendor Specific 0x8100-0x81FF RESERVED 0x8200-0xFFFF 5.2 iFCP Requirements In iFCP, use of iSNS is REQUIRED. No alternatives exist for support of iFCP Naming & Discovery functions. 5.2.1 Required Attributes for Support of iFCP The following table displays attributes that are used by iSNS to support iFCP. Attributes indicated in the REQUIRED TO IMPLEMENT column MUST be supported by the iSNS server that supports iFCP. Attributes indicated in the REQUIRED TO USE column MUST be supported by iFCP gateways. A more detailed description of each attribute is found in section 7. REQUIRED REQUIRED Object Attribute to Implement to Use ------ --------- ------------ -------- NETWORK ENTITY Entity Identifier * * Entity Protocol * * Management IP Address Timestamp * Protocol Version Range * Registration period Tseng, Gibbons, et al. Standards Track [Page 25] Internet Storage Name Service (iSNS) May 2002 Entity Index Entity IKE Phase-1 Proposal Entity Certificate PORTAL IP Address * * TCP/UDP Port * * Symbolic Name * ESI Interval * ESI Port * SCN Port * Portal IKE Phase-1 Proposal Portal IKE Phase-2 Proposal Portal Certificate Security Bitmap * STORAGE NODE FC Port Name (WWPN) * * (FC Port) Port_ID * * FC Port Type * * Port Symbolic Name * Fabric Port Name (FWWN) * Hard Address * Port IP Address * Class of Service * FC FC-4 Types * FC FC-4 Descriptors * FC FC-4 Features * SCN Bitmap * iFCP Port Role * Port Certificate FC DEVICE FC Node Name (WWNN) * * (FC Node) Node Symbolic Name * Node IP Address * Node IPA * Node Certificate Proxy iSCSI Name DISCOVERY DOMAIN DD_ID * * DD_Symbolic Name * DD iFCP Member (WWPN) * DISCOVERY DOMAIN DDS Identifier * SET DDS Symbolic Name * DDS Status * DDS Member * OTHER Switch Name Preferred_ID Assigned_ID Space Identifier Tseng, Gibbons, et al. Standards Track [Page 26] Internet Storage Name Service (iSNS) May 2002 5.2.2 Example iFCP Object Model Diagram The iFCP protocol allows native Fibre Channel devices or Fibre Channel fabrics connected to an iFCP gateway to be directly internetworked using IP. When supporting iFCP, the iSNS server stores Fibre Channel device attributes, iFCP gateway attributes, and Fibre Channel fabric switch attributes that might also be stored in an FC name server. The following diagram shows a representation of a gateway supporting multiple Fibre Channel devices behind it. The two PORTAL objects represent IP interfaces on the iFCP gateway that can be used to access any of the three STORAGE NODE objects behind it. Note that the FC DEVICE object is not contained in the NETWORK ENTITY object. However, each FC DEVICE has a relationship to one or more STORAGE NODE objects. +--------------------------------------------------------+ | IP Network | +--------+-----------------+-----------------------------+ | | +-+------+------+---+------+------+----------------------+ | | PORTAL | | PORTAL | NETWORK ENTITY | | | -IP Addr 1 | | -IP Addr 2 | -Entity ID (FQDN): | | | -TCP Port 1 | | -TCP Port 2 | ôgtwy1.foo.comö | | +-----+ +-----+ +-----+ +-----+ -Protocol: iFCP | | | | | | | | +-----+ +---------------+ +----------------------+ | | +-----+ +---------------+ +-------------+ +------+ | | | | | | | | | | +-----+ +-----+ +----+ +------+ +----+ +------+ | | |STORAGE NODE | |STORAGE NODE | |STORAGE NODE | | | | -WWPN 1 | | -WWPN 2 | | -WWPN 3 | | | | -Port ID 1 | | -Port ID 2 | | -Port ID 3 | | | | -FWWN 1 | | -FWWN 2 | | -FWWN 3 | | | | -FC COS | | -FC COS | | -FC COS | | | +------+------+ +-------+-----+ +----+--------+ | +--------|-------------------|------------|--------------+ | | | +------+------+ +---+------------+---+ | FC DEVICE | | FC DEVICE | | -WWNN 1 | | -WWNN 2 | | | | | +-------------+ +--------------------+ 5.2.3 Required Commands and Response Messages for Support of iFCP The iSNSP messages and responses displayed in the following tables are available to support iFCP gateways. Messages indicated in the REQUIRED TO IMPLEMENT column MUST be supported by the iSNS server used by iFCP gateways. Messages indicated in the REQUIRED TO USE column MUST be supported by the iFCP gateways themselves. Tseng, Gibbons, et al. Standards Track [Page 27] Internet Storage Name Service (iSNS) May 2002 REQUIRED TO: Message Description Abbreviation Func ID Implement Use ------------------- ------------ ------- --------- --- Register Dev Attr Req RegDevAttr 0x0001 * * Dev Attr Query Request DevAttrQry 0x0002 * * Dev Get Next Request DevGetNext 0x0003 * Deregister Dev Request DeregDev 0x0004 * * SCN Register Request SCNReg 0x0005 * SCN Deregister Request SCNDereg 0x0006 * SCN Event SCNEvent 0x0007 * State Change Notification SCN 0x0008 * DD Register DDReg 0x0009 * * DD Deregister DDDereg 0x000A * * DDS Register DDSReg 0x000B * * DDS Deregister DDSDereg 0x000C * * Entity Status Inquiry ESI 0x000D * Name Service Heartbeat Heartbeat 0x000E * Reserved Reserved 0x000F-0x0010 Request Switch ID RqstSwId 0x0011 Release Switch ID RlseSwId 0x0012 Get Switch IDs GetSwIds 0x0013 RESERVED 0x0014-0x00FF Vendor Specific 0x0100-0x01FF RESERVED 0x0200-0x8000 The following are iSNSP response messages in support of iFCP: Tseng, Gibbons, et al. Standards Track [Page 28] Internet Storage Name Service (iSNS) May 2002 REQUIRED TO: Response Message Desc Abbreviation Func_ID Implement Use --------------------- ------------ ------- --------- --- Register Dev Attr Rsp RegDevRsp 0x8001 * * Dev Attr Query Resp DevAttrQryRsp 0x8002 * * Dev Get Next Resp DevGetNextRsp 0x8003 * Deregister Dev Resp DeregDevRsp 0x8004 * * SCN Register Resp SCNRegRsp 0x8005 * SCN Deregister Resp SCNDeregRsp 0x8006 * SCN Event Resp SCNEventRsp 0x8007 * SCN Response SCNRsp 0x8008 * DD Register Rsp DDRegRsp 0x8009 * * DD Deregister Rsp DDDeregRsp 0x800A * * DDS Register Rsp DDSRegRsp 0x800B * * DDS Deregister Rsp DDSDeregRsp 0x800C * * Entity Stat Inquiry Resp ESIRsp 0x800D * NOT USED 0x800E RESERVED 0x800F-0x8010 Request Switch ID Resp RqstSwIdRsp 0x8011 Release Switch ID Resp RlseSwIdRsp 0x8012 Get Switch IDs GetSwIdRsp 0x0013 RESERVED 0x8014-0x80FF Vendor Specific 0x8100-0x81FF RESERVED 0x8200-0xFFFF 5.3 Use of TCP For iSNS Communication It MUST be possible to use TCP for iSNS communication. The iSNS server MUST accept TCP connections for client registrations. The well-known TCP port used by the iSNS server to receive TCP messages used is 3205. To receive ESI monitoring using TCP, the client registers the Portal ESI Interval and the port number of the TCP port that will be used to receive ESI inquiry messages. TCP-based ESI monitoring requires that an open TCP connection be maintained by the iSNS server to every iSNS client registered to receive monitoring. This TCP connection is terminated at the iSNS client at the registered ESI Port number. If the TCP connection supporting ESI monitoring is terminated, then the client must reregister for ESI messages on a new TCP connection in order to continue to receive ESI monitoring. To receive SCN notifications using TCP, the client registers the iSCSI or iFCP SCN Bitmap and the port number of the TCP port in the Portal used to receive SCN's. The TCP connection for SCN's does not necessarily need to be continuously open. It is possible for an iSNS client to use the same TCP connection for SCN, ESI, and iSNS queries. Alternatively, separate connections may be used. Tseng, Gibbons, et al. Standards Track [Page 29] Internet Storage Name Service (iSNS) May 2002 5.4 Use of UDP For iSNS Communication The iSNS server MAY accept UDP messages for client registrations. The iSNS server MUST accept registrations from clients requesting UDP-based ESI and SCN messages. The well-known UDP port used to receive UDP messages is 3205. To receive UDP-based ESI monitoring messages, the client registers the port number of the UDP port in at least one Portal to be used to receive and respond to ESI messages from the iSNS server. If an entity has multiple Portals with registered ESI UDP Ports, then ESI messages SHALL be delivered to every Portal registered to receive such messages. To receive UDP-based SCN notification messages, the client registers the port number of the UDP port in at least one Portal to be used to receive SCN messages from the iSNS server. If an entity has multiple Portals with registered SCN UDP Ports, then SCN messages SHALL be delivered to each Portal registered to receive such messages. 6. iSNSP Message Format The iSNSP message format is similar to the format of other common protocols such as DHCP, DNS and BOOTP. An iSNSP message may be sent in one or more iSNS Protocol Data Units (PDU). Each PDU is 4 byte aligned. The following describes the format of the iSNSP PDU: Byte MSb LSb Offset 0 15 16 31 +---------------------+----------------------+ 0 | iSNSP VERSION | FUNCTION ID | 4 Bytes +---------------------+----------------------+ 4 | PDU LENGTH | FLAGS | 4 Bytes +---------------------+----------------------+ 8 | TRANSACTION ID | SEQUENCE ID | 4 Bytes +---------------------+----------------------+ 12 | | | PDU PAYLOAD | N Bytes | ... | +--------------------------------------------+ 12+N | AUTHENTICATION BLOCK (Multicast Only) | L Bytes +--------------------------------------------+ Total Length = 12 + N + L 6.1 iSNSP PDU Header The iSNSP header contains the iSNSP VERSION, FUNCTION ID, PDU LENGTH, FLAGS, TRANSACTIONID, and SEQUENCE ID fields as defined below. 6.1.1 iSNSP Version The iSNSP version is currently 0x0001. Tseng, Gibbons, et al. Standards Track [Page 30] Internet Storage Name Service (iSNS) May 2002 6.1.2 iSNSP Function ID The FUNCTION ID defines the type of iSNS message and the operation to be executed. FUNCTION_ID values with the leading bit cleared indicate query and registration messages sent by the iSNS client, while FUNCTION_ID values with the leading bit set indicate response messages sent by the iSNS server. See section 5 under the appropriate protocol (i.e., iSCSI or iFCP) for a mapping of the FUNCTION_ID value to the iSNSP Command or Response message. All PDU's comprising an iSNSP message must have the same FUNCTION_ID and TRANSACTION ID value. 6.1.3 iSNSP PDU Length The iSNS PDU LENGTH specifies the length of the PDU PAYLOAD field in bytes. The payload contains the data/attribute values for the operation. 6.1.4 iSNSP Flags The FLAGS field indicates additional information about the message and the type of iSNS entity that generated the message. The following table displays the valid flags: Bit Field Enabled Means: --------- ------------- 16 Sender is the iSNS client 17 Sender is the iSNS server 18 RESERVED 19 Replace Flag (valid only for RegDevAttr) 20 Last PDU of the iSNS message 21 First PDU of the iSNS message 22-31 RESERVED 6.1.5 iSNSP Transaction ID The TRANSACTION ID is set to a unique value for each concurrently outstanding request message. Replies MUST use the same TRANSACTION ID value as the associated iSNS request message. If a message is retransmitted, the same TRANSACTION ID value MUST be used. 6.1.6 iSNSP Sequence ID The SEQUENCE ID has a unique value for each PDU within a single transaction. Each SEQUENCE_ID value in each PDU SHALL be numbered sequentially in the order that the PDU's are transmitted. If a message is retransmitted, then the original SEQUENCE_ID value MUST be used for each PDU's in the message. Note that the two-byte SEQUENCE ID allows for up to 65535 PDU's per iSNS message. 6.2 iSNSP Message Segmentation and Reassembly iSNS messages may be carried in one or more iSNS PDU's. If only one iSNS PDU is used to carry the iSNS message, then bit 21 (First PDU) Tseng, Gibbons, et al. Standards Track [Page 31] Internet Storage Name Service (iSNS) May 2002 and bit 20 in the FLAGS field (Last PDU) SHALL both be enabled. If multiple PDUs are used to carry the iSNS message, then bit 21 SHALL be enabled in the first PDU of the message, and bit 20 SHALL be enabled in the last PDU. All PDU's comprising the same iSNSP message SHALL have the same FUNCTION_ID and TRANSACTION_ID values. Each PDU comprising an iSNSP message SHALL have a unique SEQUENCE_ID value. 6.3 iSNSP Message Payload The MESSAGE PAYLOAD is variable length and contains attributes used for registration and query operations. The attribute data items use a format similar to other protocols, such as DHCP (RFC 2131) options. Each iSNS attribute is specified in the iSNSP message payload using Tag-Length-Value (TLV) data format, as shown below: Byte MSb LSb Offset 0 31 +--------------------------------------------+ 0 | Attribute Tag | 4 Bytes +--------------------------------------------+ 4 | Attribute Length (N) | 4 Bytes +--------------------------------------------+ 8 | | | Attribute Value | N Bytes | | +--------------------------------------------+ Total Length = 8 + N Attribute Tag - a 4-byte tag field that identifies the attribute as defined in section 7.1. This field contains the ID of the indicated attribute. Attribute Length - a 4-byte field that indicates the length, in bytes, of the attribute value to follow. Attribute Value - a variable-length field containing the attribute value. The above format is used to identify each attribute in the iSNS message payload. 6.3.1 Attribute Value 4-Byte Alignment All attribute values are aligned at 4 byte boundaries. For variable length attributes, the value length is increased to the next 4-byte boundary and the value is NULL padded. 6.4 iSNSP Response Error Codes All iSNSP response messages contain a 4-byte ERROR CODE field as the first field in the iSNSP PAYLOAD. If the original iSNSP request message was processed normally by the iSNS server, or the iSNS Tseng, Gibbons, et al. Standards Track [Page 32] Internet Storage Name Service (iSNS) May 2002 client for ESI and SCN messages, the field SHALL contain 0x00000000 (NO ERROR). Error Code Error Description ---------- ----------------- 0 No Error 1 Unknown Error 2 Message Format Error 3 Invalid Registration 4 Requested ESI Period Too Short 5 Invalid Query 6 Authentication Unknown 7 Authentication Absent 8 Authentication Failed 9 No Such Entry 10 Version Not Supported 11 Internal Error 12 Busy 13 Option Not Understood 14 Invalid Update 15 Message Not Supported 16 SCN Event Rejected 17 SCN Registration Rejected 18 Attribute not Implemented 19 SWITCH_ID not available 20 SWITCH_ID not allocated 21 ESI Not Available 22 And Above RESERVED 6.5 iSNS Multicast Message Authentication For iSNS multicast messages, the iSNSP provides authentication capability. The following section details the iSNS Authentication Block, which is identical in format to the SLP authentication block [RFC2608]. iSNS unicast messages SHOULD NOT include the authentication block, but rather should rely upon IPSec security mechanisms. If a PKI is available with an X.509 certificate authority, then public key authentication of the iSNS server is possible. The authentication block leverages the DSA with SHA-1 algorithm, which can easily integrate into a public key infrastructure. The authentication block contains a digital signature for the multicast message. The digital signature is calculated on a per-PDU basis. The authentication block contains the following information: Tseng, Gibbons, et al. Standards Track [Page 33] Internet Storage Name Service (iSNS) May 2002 1. A time stamp, to prevent replay attacks 2. A structured authenticator containing a signature calculated over the time stamp and the message being secured 3. An indicator of the cryptographic algorithm that was used to calculate the signature. 4. An indicator of the keying material and algorithm parameters, used to calculate the signature. The authentication block is described in the following figure: Byte MSb LSb Offset 0 1 2 3 4 5 6 7 +----------------------------------+ 0 | BLOCK STRUCTURE DESCRIPTOR | 2 Bytes +----------------------------------+ 2 | AUTHENTICATION BLOCK LENGTH | 2 Bytes +----------------------------------+ 4 | TIMESTAMP | 4 Bytes +----------------------------------+ 8 | SPI STRING LENGTH | 1 Byte +----------------------------------+ 9 | SPI STRING | N Bytes +----------------------------------+ 9 + N | STRUCTURED AUTHENTICATOR | M Bytes +----------------------------------+ Total Length = 9 + N + M BLOCK STRUCTURE DESCRIPTOR (BSD) - Defines the structure and algorithm to use for the STRUCTURED AUTHENTICATOR. Currently, the only defined value for BSD is 0x0002, which represents DSA with SHA- 1. Details on DSA can be found in [DSS]. BSD values from 0x0000 to 0x7FFF are assigned by IANA, while 0x8000 to 0x8FFF are for private use. The BSD value 0x0002 is compatible with the X.509 PKI specification, allowing easy integration of the STRUCTURED AUTHENTICATOR format with an existing PKI infrastructure. AUTHENTICATION BLOCK LENGTH - Defines the length of the authentication block, beginning with the BSD field and running through the last byte of the STRUCTURED AUTHENTICATOR. TIMESTAMP - This is a 4-byte unsigned, fixed-point integer giving the number of seconds since 00:00:00 GMT on January 1, 1970. SPI STRING LENGTH - The length of the SPI STRING field. SPI STRING (Security Parameters Index) - Index to the key and algorithm used by the message recipient to decode the STRUCTURED AUTHENTICATOR field. STRUCTURED AUTHENTICATOR - Contains the digital signature. For the default BSD value of 0x0002, this field contains the binary ASN.1 encoding of output values from the DSA with SHA-1 signature calculation. Tseng, Gibbons, et al. Standards Track [Page 34] Internet Storage Name Service (iSNS) May 2002 6.6 Registration and Query Messages The iSNSP registration and query message payloads contain a list of attributes, and have the following format: MSb LSb 0 31 +----------------------------------------+ | Source Attribute (Requests Only) | +----------------------------------------+ | Message Key Attribute[1] (if present) | +----------------------------------------+ | Message Key Attribute[2] (if present) | +----------------------------------------+ | Message Key Attribute[3] (if present) | +----------------------------------------+ | . . . | +----------------------------------------+ | - Delimiter Attribute - | +----------------------------------------+ | Operating Attribute[1] | +----------------------------------------+ | Operating Attribute[2] (if present) | +----------------------------------------+ | Operating Attribute[3] (if present) | +----------------------------------------+ | . . . | +----------------------------------------+ iSNS Registration and Query messages, sent by iSNS Clients, are sent to the iSNS IP-Address and TCP/UDP Port. The iSNS Responses will be sent to the iSNS Client IP-Address and the originating TCP/UDP Port used for the associated registration and query message. 6.6.1 Source Attribute The source attribute is used to identify the iSNS client to the iSNS server for queries and other messages that require source identification. The source attribute uniquely identifies the source of the message. Valid source attribute types are shown below. Tseng, Gibbons, et al. Standards Track [Page 35] Internet Storage Name Service (iSNS) May 2002 Valid Source Attributes ----------------------- iSCSI Name FC Port Name WWPN For a query operation, the source attribute is used to limit the scope of the specified operation to the Discovery Domains of which the source is a member. Special control nodes, identified by the Source Attribute, may be administratively configured to perform the specified operation on all objects in the iSNS database without scoping to Discovery Domains. 6.6.2 Message Key Attributes Message Key attributes are used to identify pre-existing objects in the iSNS database for iSNS query and registration messages. If the object identified by the Message Key attributes are not found in the iSNS database, then an error code of 9 (no such entry) shall be returned by the iSNS server. When registering a new NETWORK ENTITY object that did not previously exist in the iSNS database, no Message Key attribute should be used. 6.6.3 Delimiter Attribute The Delimiter Attribute separates the key attributes from the operating attributes in a message payload. The Delimiter Attribute has a tag value of 0 and a length value of 0. The Delimiter Attribute is effectively 8 Bytes long, a 4 Byte tag containing 0x00000000, and a 4 Byte length field containing 0x00000000. 6.6.4 Operating Attributes The Operating Attributes are a list of one or more attributes related to the actual iSNS registration or query operation being performed. Operating Attributes include object key attributes and non-key attributes. Object key attributes uniquely identify iSNS objects. The tag value distinguishes the attribute as an object key attribute (i.e., tag=16&17, 32, 64, and 96) or non-key attribute. The ordering of operating attributes in the message is important in determining the relationships among objects and their ownership of non-key attributes. iSNS protocol messages that violate these ordering rules SHALL be rejected with the error code of 2 (Message Format Error). Some objects are keyed by more than one object key attribute value. For example, the PORTAL object is keyed by attribute tags 16 and 17. When describing an object keyed by more than one key attribute, each and every object key attribute of that object MUST be listed sequentially by tag value in the message before non-key attributes of that object and key attributes of the next object. Tseng, Gibbons, et al. Standards Track [Page 36] Internet Storage Name Service (iSNS) May 2002 Non-key attributes that immediately follow a set of one or more object key attributes MUST be attributes of the object referenced by that set of object key attributes. All non-key attributes of an object MUST be listed before the object key attributes introducing the next object. Objects and their attributes MUST be listed in their order of inheritance hierarchy. STORAGE NODE and PORTAL objects and their respective attributes MUST follow the NETWORK ENTITY object to which they have a relationship. Similarly, FC DEVICE objects MUST follow the STORAGE NODE object to which they have a relationship. Vendor-specific objects defined by tag values in the range 1537-2048 have the same requirements described above. 6.6.4.1 Operating Attributes for Query and Get Next Requests In Query and Get Next request messages, TLV attributes with length value of 0 are used to indicate which operating attributes are to be returned in the corresponding response. Operating Attribute values that match the TLV attributes in the original message are returned in the response message. 6.6.5 Registration and Query Request Message Types The following describes each query and message type. 6.6.5.1 Register Device Attribute Request (RegDevAttr) The RegDevAttr message type is 0x0001. The RegDevAttr message provides an iSNS client with the means to register objects and attributes. Depending on the setting of the Replace bit in the FLAGS field, the Operating attribute values in the RegDevAttr message will either replace existing attributes, or be added to existing attributes. See section 6.6.5.1.1 below for a complete description of the Replace Flag. The operating attributes represent new objects and attributes that will be registered. Multiple objects and attributes can be registered in one RegDevAttr. The ordering of the objects in this message indicate the structure of associations among the objects to be created in the iSNS server. To create a relationships between a parent ENTITY object and its PORTAL and STORAGE NODE objects, the registration message SHALL list the key and operating attributes of the ENTITY object, followed by the attributes of each PORTAL and STORAGE NODE object to be linked to that ENTITY. Similarly, FC DEVICE object attributes that follow a STORAGE NODE object are considered to have a subordinate relationship with that STORAGE NODE. A maximum of one new ENTITY object can be created with a single RegDevAttr message; there is no limit to the number of PORTAL, STORAGE NODE, and FC DEVICE objects that can be created for the ENTITY registered by the RegDevAttr message. Tseng, Gibbons, et al. Standards Track [Page 37] Internet Storage Name Service (iSNS) May 2002 A RegDevAttr message with no Message Key Attribute results in creation of a new NETWORK ENTITY object. If the EID attribute (with non-zero length) is included among the operating attributes in the RegDevAttr message, then the new NETWORK ENTITY SHALL be assigned the value contained in that EID attribute. Otherwise, if the EID attribute is not contained among the operating attributes of the RegDevAttr message, or if the EID is an operating attribute with TLV length of 0, then the iSNS server SHALL create the EID for the new NETWORK ENTITY that is registered in the iSNS database and returned in the RegDevAttr Response message. Note that a registration message that creates a new iSNS database entry that does not contain at least one PORTAL and one STORAGE NODE shall be considered invalid. Invalid registrations shall return a response with error code of 3 (Invalid Registration). 6.6.5.1.1 Replace Flag The Replace Flag, contained in the message header FLAGS field, indicates whether the registration is a replacement of, or update to, an existing object. If the object key attributes of a registration message do not match an existing object in the iSNS database, then the Replace flag is irrelevant; a new object is created regardless of whether the Replace flag is enabled or not. If the object key attributes match an existing object in the iSNS database, and the Replace flag is enabled, then the registration will replace the existing entry in the iSNS database. The existing object(s) specified in the RegDevAttr message shall be de- registered. A new registration shall be created with the new attribute value(s) in the registration request. Existing associations between objects will be updated to reflect the new information. For example, an existing STORAGE NODE object may be de-registered and reregistered with a different NETWORK ENTITY object with a single registration message. If the object key attributes match an existing object in the iSNS database, and the Replace flag is not enabled, then the new attribute value(s) in the registration request SHALL update existing values and may add new, additional attributes for the object key entry. Only non-key attributes can be updated. Existing associations between objects will be maintained and SHALL NOT be changed if the Replace flag is not enabled. If a registration update of the existing object would cause a change in associations, then the error ôInvalid Updateô SHALL be returned. For example, if a RegDevAttr message with an Entity Identifier key for one NETWORK ENTITY object contains a STORAGE NODE object attribute associated with different NETWORK ENTITY object, then an error shall be returned. Tseng, Gibbons, et al. Standards Track [Page 38] Internet Storage Name Service (iSNS) May 2002 6.6.5.2 Device Attribute Query Request (DevAttrQry) The DevAttrQry message type is 0x0002. The DevAttrQry message provides an iSNS client with the means to query the iSNS server for objects and attributes. The source is used to scope the query to the Discovery Domains that the source attribute is a member of. The Message Key Attribute(s) follow the source attribute in the message payload. The attributes returned by the query will be from objects WHERE the Message Key Attribute(s) match the object. The Message Key Attributes map to a type of object. If no operating attributes are included in the DevAttrQry, then all operating attributes of the object and sub-objects identified by the message key attribute(s) SHALL be returned in the response message. For queries by non-control nodes, any objects matching the Message Key Attributes that are not in the same Discovery Domain as the Source Attribute SHALL NOT be included in the response message. Registration and query messages for iSNS server-specific attributes (i.e., tags in the range 132 to 384) shall be formatted using the identifying key attribute of the STORAGE NODE originating the query (i.e., iSCSI Name or FC Port Name WWPN) for both the source attribute and message key attribute. Operating attributes shall include the TLV of the server-specific attribute being requested. The DevAttrQry message shall support the following minimum set of Message Key Attributes: Valid Message Key Attributes for Queries ---------------------------------------- Entity Identifier Entity Protocol Portal IP-Address Portal IP-Address, Portal TCP/UDP Port iSCSI Node Type iSCSI Identifier FC Port Name WWPN FC Port Type FC-4 Type Source Attribute (for server-specific attributes) Switch Name (FC Device WWNN--for space identifier queries) 6.6.5.3 Device Get Next Request (DevGetNext) The DevGetNext message type is 0x0003. This message provides the iSNS client with the means to retrieve each and every Entity, Portal, iSCSI Node, FC Port Name, or FC Node Name attribute from DD's to which the client has access. The source attribute is used to scope the retrieval process to the Discovery Domains that the source attribute is a member of. Tseng, Gibbons, et al. Standards Track [Page 39] Internet Storage Name Service (iSNS) May 2002 The Message Key Attribute follows the source attribute in the message payload. The Message Key Attribute may be an Entity Identifier (EID), iSCSI Name, Portal IP Address and TCP/UDP Port, FC Node Name WWNN, or FC Port Name WWPN. If the key TLV length value entered is zero, signifying an empty key value field, then the first accessible Entity Identifier, iSCSI Name, Portal IP Address and TCP/UDP Port, FC Node name, or FC Port Name instance shall be returned to the client. DevGetNext SHALL return the object that is stored after the object matching the key provided. If the key provided matches the last object instance, then the Error Code of "No Such Entry" SHALL be returned in the response. The values of the matching Operating Attributes listed in the original DevGetNext message SHALL be returned in the DevGetNext response. 6.6.5.4 Deregister Device Request (DeregDev) The DeregDev message type is 0x0004. An iSNS client port or device is removed from the iSNS database by using DeregDev. Upon receiving the DeregDev, the iSNS server removes all object registrations associated with the Message Key Attribute in the payload. The DeregDev request message payload contains a Source Attribute and Message Key Attribute(s). Valid Key Attributes are shown below: Valid Message Key Attributes for DeregDev ----------------------------------------- Entity Identifier Portal IP-Address Portal IP-Address, Portal TCP/UDP Port iSCSI Name FC Port Name WWPN FC Node Name WWNN The removal of the object will initiate an SCN message to registered iSNS clients that are in the same DD as the removed device or port. After removing the port or device, the iSNS server sends back an acknowledgement to the iSNS client. If all nodes associated with an entity are deregistered from that entity, then the entity SHALL also be removed UNLESS the entity (through one or more Portals) is responding to ESI's. If all Portals associated with an entity are deregistered from that entity, then that entity and all associated nodes SHALL be removed from the iSNS database. 6.6.5.5 SCN Register Request (SCNReg) The SCNReg message type is 0x0005. The State Change Notification Registration Request (SCNReg) message allows an iSNS client to register a STORAGE NODE to receive State Change Notification (SCN) messages. Tseng, Gibbons, et al. Standards Track [Page 40] Internet Storage Name Service (iSNS) May 2002 SCN messages are sent to each indicated UDP or TCP Port specified in the SCN Port field (tag 23) of each PORTAL object. The SCN notifies the iSNS client of changes within the DD or network. Note that while SCNReg sets the SCN Bitmap field, the RegDevAttr message registers the UDP or TCP Port used by each Portal to receive SCN messages. If no SCN Port fields of any Portals of the iSNS client are registered to receive SCN messages, then the SCNReg message SHALL be rejected with error code 17 (SCN Registration Rejected). The SCNReg request message payload contains a Source Attribute, a Message Key Attribute(s), and an Operating Attribute. Valid Message Key Attributes for an SCNReg are shown below: Valid Message Key Attributes for SCNReg --------------------------------------- iSCSI Name FC Port Name WWPN Nodes with iSCSI Name or FC Port Name WWPN attributes that match the Message Key Attributes in the SCNReg message are registered to receive SCNs using the specified SCN bitmap. The SCN Bitmap is the only operating attribute of this message, and it always overwrites the previous contents of this field in the iSNS database. The bitmap indicates those INTERESTED EVENT TYPES the node is registering for. Note that the settings of this bitmap determine whether the SCN registration is for a regular SCN's or management SCN's. Only control nodes MAY conduct registrations for management SCN's; iSNS clients that are not control nodes MUST NOT conduct mangement SCN registrations. Note that control nodes that register for management SCN's receive a copy of every SCN message generated by the iSNS server. Therefore, management registrations should be used sparingly in order to conserve iSNS server resources, and the control nodes that conduct such registrations should be prepared to receive the anticipated volume of SCN message traffic. 6.6.5.6 SCN Deregister Request (SCNDereg) The SCNDereg message type is 0x0006. The SCNDereg message allows an iSNS client to disable State Change Notification (SCN) messages. The SCNDereg request message payload contains a Source Attribute and Message Key Attribute(s). Valid Message Key Attributes for an SCNDereg are shown below: Valid Message Key Attributes for SCNDereg ----------------------------------------- iSCSI Name FC Port Name WWPN Nodes with iSCSI Name or FC Port Name WWPN attributes that match the Message Key Attributes in the SCNDereg message are deregistered for Tseng, Gibbons, et al. Standards Track [Page 41] Internet Storage Name Service (iSNS) May 2002 SCNs. The SCN bitmap field of such nodes are cleared, and no SCN messages shall be sent for changes to that node. There are no Delimiter or Operating Attributes in the SCNDereg message. 6.6.5.7 SCN Event (SCNEvent) The SCNEvent message type is 0x0007. The SCNEvent is a message sent by an iSNS client to request generation of a State Change Notification (SCN) message by the iSNS server. The SCN, sent by the iSNS server, then notifies iFCP, iSCSI, and control nodes within the affected DD of the change indicated in the SCNEvent. Most SCNs are automatically generated by the iSNS server when nodes are registered or deregistered from the directory database. SCNs are also generated when a network management application makes changes to the DD membership in the iSNS server. However, an iSNS client can trigger an SCN by using SCNEvent. The SCNEvent message payload contains a Source Attribute, Message Key Attribute, and Operating Attribute. Valid Key Attributes for an SCNEvent are shown below: Valid Message Key Attributes for SCNEvent ----------------------------------------- iSCSI Name FC Port Name WWPN The Operating Attributes section SHALL contain the SCN Event Bitmap attribute. The bitmap indicates the event that caused the SCNEvent to be generated. 6.6.5.8 State Change Notification (SCN) The SCN message type is 0x0008. The SCN is a message generated by the iSNS server, notifying a registered iFCP, iSCSI, or control node of changes. There are two types of SCN registrations: regular registrations and management registrations. Regular SCN's notify iSNS clients of events within the discovery domain. Management SCN's notify control nodes that register for management SCN's of events occuring anywhere in the network. The SCN message is sent to each Portal of the registered STORAGE NODE that has a registered TCP or UDP Port value in the SCN Port field. The types of events that can trigger an SCN message, and the amount of information contained in the SCN message, depend on the registered SCN Event Bitmap for the iSNS client. The format of the SCN payload is shown below: Tseng, Gibbons, et al. Standards Track [Page 42] Internet Storage Name Service (iSNS) May 2002 +----------------------------------------+ | Destination Attribute | +----------------------------------------+ | Timestamp | +----------------------------------------+ | Source SCN Bitmap 1 | +----------------------------------------+ | Source Attribute [1] | +----------------------------------------+ | Source Attribute [2](if present) | +----------------------------------------+ | Source Attribute [3](if present) | +----------------------------------------+ | Source Attribute [n](if present) | +----------------------------------------+ | Source SCN Bitmap 2 (if present) | +----------------------------------------+ | . . . | +----------------------------------------+ All payload attributes are in TLV format. The Destination Attribute is the node identifier that is receiving the SCN. The Destination Attribute can be an iSCSI Name, or FC Port Name. The Timestamp field, using the Timestamp TLV format, indicates the time the SCN was generated. The Source Attributes describe the object(s) that are affected by the event causing the SCN to be generated. For regular SCN messages, the Source Attributes can be an iSCSI Name or FC Port Name WWPN. For management SCN messages, the Source Attributes can be an iSCSI Name, DD ID, DDS ID, or FC Port Name WWPN. The provided source attribute can then be used by the iSNS client in a follow-up query to more fully learn of the changes in the iSNS database that triggered the SCN. For example, a management SCN to notify a control node of a new DD within a Discovery Domain Set would contain both the DD_ID and the DDS_ID of the affected Discovery Domain and Discovery Domain Set among the source attributes. A regular SCN to notify an iSNS client of a new PORTAL available for particular iSCSI target would contain the iSCSI Name of the target device among the source attributes. The Source SCN Bitmap field indicates the type of SCN notification (i.e., regular or management SCN), and the type of event that caused the SCN to be generated; it does not necessarily correlate with the original SCN bitmap registered in the iSNS server. This field is also used as a delimiter between information about multiple objects, if the SCN message is providing multiple SCN notifications. See sections 7.4.4 and 7.5.12 for additional information on the SCN Bitmap. Tseng, Gibbons, et al. Standards Track [Page 43] Internet Storage Name Service (iSNS) May 2002 6.6.5.9 DD Register (DDReg) The DDReg message type is 0x0009. This message is used to create a new Discovery Domain (DD), update an existing DD Symbolic Name, and/or add DD members. DDs are uniquely defined using DD_IDs. DD registration attributes are described in section 7.9. The DDReg message payload contains the Source Attribute, and optionally Key and Operating Attributes. A DDReg message with no Message Key Attribute results in creation of a new Discovery Domain (DD). If the DD_ID attribute (with non-zero length) is included among the operating attributes in the DDReg message, then the new Discovery Domain SHALL be assigned the value contained in that DD_ID attribute. Otherwise, if the DD_ID attribute is not contained among the operating attributes of the DDReg message, or if the DD_ID is an operating attribute with TLV length of 0, then the iSNS server SHALL assign the DD_ID value that is returned in the DDReg Response message. The Operating Attributes can contain the iSCSI Node Identifier or iFCP WWPN of iSNS clients to be added to the DD. It may also contain the DD_Symbolic_Name of the DD. This message shall add any DD members listed as operating attributes to the Discovery Domain specified by the DD_ID. In addition, if the DD_Symbolic_Name is an operating attribute, then it will be stored in the iSNS database as the DD_Symbolic_Name for the specified Discovery Domain. 6.6.5.10 DD Deregister (DDDereg) The DDDereg message type is 0x000A. This message allows an iSNS client to deregister an existing Discovery Domain (DD) or remove members from an existing DD. DDs are uniquely defined using DD_IDs. DD registration attributes are described in section 7.9. The DDDereg message payload contains a Source Attribute, Message Key Attribute, and Operating Attributes. The Message Key Attribute for a DDDereg message is the DD ID for the domain being removed, or having members removed. If the DD ID matches an existing DD, and there are no operating attributes, then the DD will be removed and a success error code returned. If the Message Key Attribute does not match an existing DD then the error code ôNo Such Entryö will be returned. If the DD ID matches an existing DD, and there are operating attributes matching DD members, then the DD members identified by the operating attributes SHALL be removed from the DD and a success Tseng, Gibbons, et al. Standards Track [Page 44] Internet Storage Name Service (iSNS) May 2002 error code returned. If any of the operating attributes do not match existing DD members, then the error code ôNo Such Entryö will be returned, and no DD members shall be removed. 6.6.5.11 DDS Register (DDSReg) The DDSReg message type is 0x000B. This message allows an iSNS client to create a new Discovery Domain Set (DDS), update an existing DDS Symbolic Name, or add DDS members. DDSÆs are uniquely defined using DDS_IDÆs. DDS registration attributes are described in section 7.9.1. The DDSReg message payload contains the Source Attribute, and optionally, Message Key and Operating Attributes. A DDSReg message with no Message Key Attribute results in creation of a new Discovery Domain Set (DDS). If the DDS_ID attribute (with non-zero length) is included among the operating attributes in the DDSReg message, then the new Discovery Domain Set SHALL be assigned the value contained in that DDS_ID attribute. Otherwise, if the DDS_ID attribute is not contained among the operating attributes of the DDSReg message, or if the DDS_ID is an operating attribute with TLV length of 0, then the iSNS server SHALL assign the DDS_ID value that is returned in the DDSReg Response message. The Operating Attributes can contain the DDS_Symbolic_Name and the DD_IDÆs of Discovery Domains to be added to the DDS. This message shall add any DDS members listed as operating attributes to the Discovery Domain Set specified by the DDS_ID Message Key Attribute. In addition, if the DDS_Symbolic_Name is an operating attribute, then it will be stored in the iSNS database as the DDS_Symbolic_Name for the specified Discovery Domain Set. 6.6.5.12 DDS Deregister (DDSDereg) The DDSDereg message type is 0x000C. This message allows an iSNS client to deregister an existing Discovery Domain Set (DDS) or remove some DDÆs from an existing DDS. The DDSDereg message payload contains a Source Attribute, Message Key Attribute, and Operating Attributes. The Message Key Attribute for a DDSDereg message is the DDS ID for the set being removed, or having members removed. If the DDS ID matches an existing DDS, and there are no operating attributes, then the DDS will be removed and a success error code returned. If the Message Key Attribute does not match an existing DDS then the error code ôNo Such Entryö will be returned. If the DDS ID matches an existing DDS, and there are operating attributes matching DDS members, then the DDS members will be removed from the DDS and a success error code returned. If any of Tseng, Gibbons, et al. Standards Track [Page 45] Internet Storage Name Service (iSNS) May 2002 the operating attributes do not match existing DDS members, then the error code ôNo Such Entryö will be returned and no DDS members shall be removed. 6.6.5.13 Entity Status Inquiry (ESI) The ESI message type is 0x000D. This message is sent by the iSNS server, and is used to verify that an iSNS client portal is reachable and available. The ESI message is sent to the ESI UDP port provided during registration, or the TCP connection used for ESI registration, depending on which communication type that is being used. The ESI message payload contains several attributes in TLV format, including the current iSNS timestamp, the EID, the Portal IP Address, and Portal TCP/UDP Port. The ESI response message payload contains the Attributes from the original ESI message. If the iSNS client portal fails to respond to an administratively- determined number of consecutive ESI messages, then the iSNS server SHALL remove that client portal from the iSNS database. If there are no other remaining ESI monitored portals for the associated entity, then the entity SHALL also be removed. The appropriate State Change Notifications, if any, SHALL be triggered. 6.6.5.14 Name Service Heartbeat (Heartbeat) This message SHOULD only be sent by the active iSNS server. It allows iSNS clients and backup servers listening to the broadcast or multicast address to discover the IP address of the primary and backup iSNS servers. It also allows concerned parties to monitor the health and status of the primary iSNS server. This message is NOT in TLV format. There is no response message to the Name Service Heartbeat. Tseng, Gibbons, et al. Standards Track [Page 46] Internet Storage Name Service (iSNS) May 2002 MSb LSb 0 31 +------------------------------------------------+ | Active Server IP-Address | +------------------------------------------------+ | iSNS TCP Port | iSNS UDP Port | +------------------------------------------------+ | Interval | +------------------------------------------------+ | Counter | +------------------------------------------------+ | RESERVED | Backup Servers | +------------------------------------------------+ | Primary Backup Server IP Address(if any) | +------------------------------------------------+ |Backup TCP Port(if any)|Backup UDP Port(if any) | +------------------------------------------------+ | 2nd Backup Server IP Address(if any) | +------------------------------------------------+ |Backup TCP Port(if any)|Backup UDP Port(if any) | +------------------------------------------------+ | . . . | +------------------------------------------------+ | VENDOR SPECIFIC | +------------------------------------------------+ The heartbeat payload contains: Active Server IP-Address: the IP_Address of the active iSNS server in IPv6 format. Active TCP Port: the TCP Port of the server currently in use Active UDP Port: the UDP Port of the server currently in use, otherwise 0 Interval: the interval, in seconds, of the heartbeat Counter: a monotonically incrementing count of heartbeats sent Backup Servers: the number of iSNS backup servers. The IP address, TCP Port, and UDP Port of each iSNS backup server follow this field. Note that if backup servers are used, then the active iSNS server SHOULD list be among the list of backup servers. The content of the remainder of this message after the list of backup servers is vendor-specific. Vendors may use additional fields to coordinate between multiple iSNS servers, and/or to identify vendor specific features. 6.6.5.15 Request Switch ID (RqstSwId) The RqstSwId message type is 0x0011. This message is used for iFCP Transparent Mode to allocate non-overlapping SWITCH_ID values Tseng, Gibbons, et al. Standards Track [Page 47] Internet Storage Name Service (iSNS) May 2002 between 1 and 239. The iSNS server becomes the address assignment authority for the entire iFCP fabric. To obtain multiple SWITCH_ID values, this request must be repeated multiple times to the iSNS server. iSNS clients that acquire SWITCH_ID values from an iSNS server MUST register for ESI monitoring from that iSNS server. The RqstSwId payload contains three TLV attributes in the following order: the requesting Switch Name (WWN) as the source attribute, the Space Identifier as the Message Key Attribute, and Preferred ID as the operating attribute. The Space Identifier is a string identifying the domain space for which the iSNS server shall allocate non-overlapping integer SWITCH_ID values between 1 and 239. The Preferred_ID is the nominal SWITCH_ID value requested by the iSNS client. If the Preferred_ID value is available and has not been already allocated for the Space_Identifier specified in the message, the iSNS server shall return the requested Preferred_ID value as the Assigned_ID to the requesting client. The RqstSwId response contains an Error Code, and the TLV attribute Assigned ID, which contains the integer value in the space requested. If no further unallocated values are available from this space, the iSNS server SHALL respond with the error code 18 "SWITCH_ID not available". Once a SWITCH_ID value has been allocated to an iSNS client by the iSNS server for a given Space_Identifier, that SWITCH_ID value SHALL NOT be reused until it has been deallocated, or ESI monitoring detects that the iSNS client no longer exists on the network and objects for that client are removed from the iSNS database. The iSNS server and client SHALL use TCP to transmit and receive RqstSwId, RqstSwIdRsp, RlseSwId, and RlseSwIdRsp messages. 6.6.5.16 Release Switch ID (RlseSwId) The RlseSwId message type is 0x0012. This message may be used by iFCP Transparent Mode to release integer identifier values used to assign 3-byte Fibre Channel PORT_ID values. The RlseSwId message contains three TLV attributes in the following order: the requesting entity EID as the source attribute, the Space_Identifier as the Message Key Attribute, and Assigned_ID as the operating attribute. Upon receiving the RlseSwId message, the iSNS server shall deallocate the SWITCH_ID value contained in the Assigned_ID attribute for the Space_Identifier attribute specified. Upon deallocation, that SWITCH_ID value can now be requested by, and assigned to, a different iSNS client. The iSNS server and client SHALL use TCP to transmit and receive RqstSwId, RqstSwIdRsp, RlseSwId, and RlseSwIdRsp messages. Tseng, Gibbons, et al. Standards Track [Page 48] Internet Storage Name Service (iSNS) May 2002 6.6.5.17 Get Switch IDs (GetSwIds) The GetSwIds message type is 0x0013. This message is used to learn the currently-allocated SWITCH_ID values for a given Space_Identifier. The GetSwIds message payload contains a Source Attribute and Message Key Attribute. The Message Key Attribute for the GetSwIds message is the Space_Identifier. The response to this message returns all of the SWITCH_ID values that have been allocated for the Space_Identifier specified. 6.7 Response Messages The iSNSP response message payloads contain an Error Code, followed by a list of attributes, and have the following format: MSb LSb 0 31 +----------------------------------------+ | 4-byte ERROR CODE | +----------------------------------------+ | Message Key Attribute[1] (if present) | +----------------------------------------+ | Message Key Attribute[2] (if present) | +----------------------------------------+ | Message Key Attribute[3] (if present) | +----------------------------------------+ | . . . | +----------------------------------------+ | - Delimiter Attribute - (if present) | +----------------------------------------+ | Operating Attribute[1] (if present) | +----------------------------------------+ | Operating Attribute[2] (if present) | +----------------------------------------+ | Operating Attribute[3] (if present) | +----------------------------------------+ | . . . | +----------------------------------------+ The iSNS Response messages will be sent to the iSNS Client IP Address and the originating TCP/UDP Port that was used for the associated registration and query message. 6.7.1 Error Code The first field in an iSNSP response message payload is the Error Code for the operation that was performed. The Error Code format is defined in section 6.4. Tseng, Gibbons, et al. Standards Track [Page 49] Internet Storage Name Service (iSNS) May 2002 6.7.2 Message Key Attributes in Response Depending on the specific iSNSP request, the response message will contain Message Key Attributes. For example, a Register Device Attribute Response message will contain the Message Key Attributes used in the Device Attribute Registration with the assigned values, if they were assigned by the iSNS server. 6.7.3 Delimiter Attribute in Response The Delimiter Attribute separates the key and operating attributes in a response message, if they exist. The Delimiter Attribute has a tag value of 0 and a length value of 0. The Delimiter Attribute is effectively 8 Bytes long, a 4 Byte tag containing 0x00000000, and a 4 Byte length field containing 0x00000000. 6.7.4 Operating Attributes in Response The Operating Attributes in a response are the results related to the iSNS registration or query operation being performed. 6.7.5 Registration and Query Response Message Types The following describes each query and message type. 6.7.5.1 Register Device Attribute Response (RegDevRsp) The RegDevRsp message type is 0x8001. The RegDevRsp message contains the results for the RegDevAttr message with the same TRANSACTION ID. The Error Code contains the operation results. If the registration completed successfully the code of ôNo Errorö is returned. If an error occurred then the appropriate code will be returned. The Message Key Attributes contain the set of keys for the objects registered by the Register Device Attribute message. If the iSNS server assigned the Entity Identifier for a network entity, then the Message Key Attribute field shall contain the assigned Entity Identifier. There are no Operating Attributes in the RegDevRsp message. 6.7.5.2 Device Attribute Query Response (DevAttrQryRsp) The DevAttrQryRsp message type is 0x8002. The DevAttrQryRsp message contains the results for the DevAttrQry message with the same TRANSACTION ID. The Error Code contains the operation results. If the query completed successfully the code of ôNo Errorö is returned. If an error occurred then the appropriate code will be returned. Tseng, Gibbons, et al. Standards Track [Page 50] Internet Storage Name Service (iSNS) May 2002 If no operating attributes are included in the original query, then all operating attributes SHALL be returned in the response. For a successful query result, the DevAttrQryRsp Operating Attributes will contain the results of the original DevAttrQry message. 6.7.5.3 Device Get Next Response (DevGetNextRsp) The DevGetNextRsp message type is 0x8003. The DevGetNextRsp message contains the results for the DevGetNext message with the same TRANSACTION ID. The Error Code contains the operation results. If the operation completed successfully the code of ôNo Errorö is returned. If an error occurred then the appropriate code will be returned. The Message Key Attribute field contains the next key after the Message Key Attribute in the original DevGetNext message. The Operating Attribute field contains the same attributes as in the DevGetNext message. The values of the Operating Attributes are the attribute values associated with the key returned. 6.7.5.4 Deregister Device Response (DeregDevRsp) The DeregDevRsp message type is 0x8004. If the DeregDev operation completed successfully then the code of ôNo Errorö is returned. If an error occurred then the appropriate code will be returned. The DeregDevRsp message does not contain any key or operating attributes. 6.7.5.5 SCN Register Response (SCNRegRsp) The SCNRegRsp message type is 0x8005. If the SCReg operation completed successfully then the code of ôNo Errorö is returned. If an error occurred then the appropriate code will be returned. The SCNRegRsp message does not contain any key or operating attributes. 6.7.5.6 SCN Deregister Response (SCNDeregRsp) The SCNDeregRsp message type is 0x8006. If the SCNDereg operation completed successfully then the code of ôNo Errorö is returned. If an error occurred then the appropriate code will be returned. The SCNDeregRsp message does not contain any key or operating attributes. Tseng, Gibbons, et al. Standards Track [Page 51] Internet Storage Name Service (iSNS) May 2002 6.7.5.7 SCN Event Response (SCNEventRsp) The SCNEventRsp message type is 0x8007. If the SCNEvent operation completed successfully then the Error Code of ôNo Errorö is returned. If an error occurred then the appropriate code will be returned. The SCNEventRsp message does not contain any key or operating attributes. 6.7.5.8 SCN Response (SCNRsp) The SCNRsp message type is 0x8008. This message is sent by an iSNS client, and provides confirmation that the SCN message was received and processed. If the SCN operation completed successfully, then the Error Code of ôNo Errorö is returned by the iSNS client. If an error occurred then the appropriate code will be returned. The SCNRsp response message payload also contains the SCN Destination Attribute representing the node or entity identifier that received the SCN. 6.7.5.9 DD Register Response (DDRegRsp) The DDRegRsp message type is 0x8009. If the DDReg operation completed successfully then the code of ôNo Errorö is returned. If an error occurred then the appropriate code will be returned. If successful, the DD ID of the DD created or updated during the DDReg operation will be returned as an operating attribute of the message. 6.7.5.10 DD Deregister Response (DDDeregRsp) The DDDeregRsp message type is 0x800A. If the DDDereg operation completed successfully then the code of ôNo Errorö is returned. If an error occurred then the appropriate code will be returned. The DDDeregRsp message does not contain any key or operating attributes. 6.7.5.11 DDS Register Response (DDSRegRsp) The DDSRegRsp message type is 0x800B. If the DDSRegRsp operation completed successfully then the code of ôNo Errorö is returned. If an error occurred then the appropriate code will be returned. If successful, the DDS ID of the DDS created or updated during the DDSReg operation will be returned as an operating attribute of the message. Tseng, Gibbons, et al. Standards Track [Page 52] Internet Storage Name Service (iSNS) May 2002 6.7.5.12 DDS Deregister Response (DDSDeregRsp) The DDSDeregRsp message type is 0x800C. If the DDSDeregRsp operation completed successfully then the code of ôNo Errorö is returned. If an error occurred then the appropriate code will be returned. The DDSDeregRsp message does not contain any key or operating attributes. 6.7.5.13 Entity Status Inquiry Response (ESIRsp) The ESIRsp message type is 0x800D. This message is sent by an iSNS client, and provides confirmation that the ESI message was received and processed. The ESIRsp response message payload contains the attributes from the original ESI message. These attributes represent the iSNS client portal that is responding to the ESI. The ESIRsp Attributes are in the order they were provided in the original ESI message. An error code of "No Error" is returned. Upon receiving the ESIRsp from the iSNS client, the iSNS server SHALL update the timestamp attribute for that client entity and portal. 6.7.5.14 Request Switch ID Response (RqstSwIdRsp) The RqstSwIdRsp message type is 0x8011. This message provides the response for RqstSwId. The RqstSwId response contains an Error Code and the TLV attribute Assigned ID, which contains the integer value in the space requested. If no further unallocated values are available from this space, the iSNS server SHALL respond with the error code 19 "SWITCH_ID not available". Once a SWITCH_ID value is allocated by the iSNS server, it shall not be reused until it has been deallocated by the iSNS client to which the value was assigned, or the ESI message detects that the iSNS client no longer exists on the network. The iSNS server and client SHALL use TCP to transmit and receive RqstSwId, RqstSwIdRsp, RlseSwId, and RlseSwIdRsp messages. 6.7.5.15 Release Switch ID Response (RlseSwIdRsp) The RlseSwIdRsp message type is 0x8012. This message provides the response for RlseSwId. The response contains an Error indicating if the request was successful or not. If the Assigned_ID value in the original RlseSwId message is not allocated, then the iSNS server SHALL respond with this message using the error code 20 ôSWITCH_ID not allocatedö. Tseng, Gibbons, et al. Standards Track [Page 53] Internet Storage Name Service (iSNS) May 2002 The iSNS server and client SHALL use TCP to transmit and receive RqstSwId, RqstSwIdRsp, RlseSwId, and RlseSwIdRsp messages. 6.7.5.16 Get Switch IDs Response (GetSwIdRsp) The GetSwIdsResp message type is 0x8013. This message is used determine which SWITCH_ID values have been allocated for the Space_Identifier specified in the original GetSwId request message. The GetSwIds response message payload contains an error code indicating if the request was successful, and a list of the Assigned IDs from the space requested. The Assigned_ID attributes are listed in TLV format. 6.8 Vendor Specific Messages Vendor-specific iSNSP messages have a functional ID of between 0x0100 and 0x01FF, while vendor-specific responses have a functional ID of between 0x8100 and 0x81FF. The first Message Key Attribute in a vendor-specific message SHALL be the company OUI (tag=256) identifying original creator of the proprietary iSNSP message. The contents of the remainder of the message are vendor-specific. 7. iSNS Message Attributes The following are attributes stored in the iSNS server, which can be retrieved using iSNS queries. Unless otherwise indicated, these attributes are supplied by iSNS clients using iSNS registration messages. 7.1 iSNS Attribute Summary The following table lists all iSNSP message attributes: Tseng, Gibbons, et al. Standards Track [Page 54] Internet Storage Name Service (iSNS) May 2002 T Entity Attributes Length Tag Reg Key Query Key - ----------------- ------ --- ------- --------- Delimiter 0 0 N/A N/A ^ Entity Identifier (EID) 0-255 1 1 1|2|16,17|32|64 & Entity Protocol 4 2 1 1|2|16,17|32|64 Mgt IP Address 16 3 1 1|2|16,17|32|64 = Timestamp 8 4 1 1|2|16,17|32|64 Protocol Version Range 4 5 1 1|2|16,17|32|64 Registration Period 4 6 1 1|2|16,17|32|64 Entity Index 4 7 1 1|2|16,17|32|64 Entity ISAKMP Phase-1 var 11 1 1|2|16,17|32|64 * Entity Certificate var 12 1 1|2|16,17|32|64 # Portal IP Address 16 16 1 1|16,17|32|64 $ Portal TCP/UDP Port 4 17 1 1|16,17|32|64 Portal Symbolic Name 0-255 18 16,17 1|16,17|32|64 ESI Interval 4 19 16,17 1|16,17|32|64 ESI Port 4 20 16,17 1|16,17|32|64 Portal Group Tag 4 21 16,17 1|16,17|32|64 Portal Index 4 22 16,17 1|16,17|32|64 SCN Port 4 23 16,17 1|16,17|32|64 Portal Security Bitmap 4 27 16,17 1|16,17|32|64 * Portal ISAKMP Phase-1 var 28 16,17 1|16,17|32|64 * Portal ISAKMP Phase-2 var 29 16,17 1|16,17|32|64 * Portal Certificate var 31 16,17 1|16,17|32|64 # iSCSI Name 0-255 32 1% 1|16,17|32|33 & iSCSI Node Type 4 33 32 1|16,17|32 iSCSI Alias 0-255 34 32 1|16,17|32 iSCSI SCN Bitmap 4 35 32 1|16,17|32 iSCSI Node Index 4 36 32 1|16,17|32 WWNN Token 8 37 32 1|16,17|32 iSCSI AuthMethod var 42 32 1|16,17|32 * iSCSI Node Certificate var 43 32 1|16,17|32 # FC Port Name WWPN 8 64 1% 1|16,17|64|66|96|128 Port ID 3 65 64 1|16,17|64 FC Port Type 4 66 64 1|16,17|64 Symbolic Port Name 0-255 67 64 1|16,17|64 Fabric Port Name 8 68 64 1|16,17|64 Hard Address 3 69 64 1|16,17|64 Port IP-Address 16 70 64 1|16,17|64 Class of Service 4 71 64 1|16,17|64 FC-4 Types 32 72 64 1|16,17|64 FC-4 Descriptor 0-255 73 64 1|16,17|64 FC-4 Features 128 74 64 1|16,17|64 iFCP SCN bitmap 4 75 64 1|16,17|64 Port Role 4 76 64 1|16,17|64 * Port Certificate var 83 64 1|16,17|64 FC-4 Type Code 4 95 Query Key only # FC Node Name WWNN 8 96 64 1|16,17|64|96 Symbolic Node Name 0-255 97 96 64|96 Node IP-Address 16 98 96 64|96 Node IPA 8 99 96 64|96 * Node Certificate var 100 96 64|96 Proxy iSCSI Name 0-255 101 96 64|96 Switch Name 8 128 128 Tseng, Gibbons, et al. Standards Track [Page 55] Internet Storage Name Service (iSNS) May 2002 Preferred ID 4 129 128 128 Assigned ID 4 130 128 128 Space_Identifier 0-255 131 128 128 RESERVED--server-specific 132-255 SOURCE SOURCE Attribute iSNS Server Vendor OUI 4 256 ------ SOURCE Attribute * Vendor-Spec iSNS Srvr var 257-384 SOURCE SOURCE Attribute * Vendor-Spec Entity var 385-512 1 1|2|16,17|32|64 * Vendor-Spec Portal var 513-640 16,17 1|16,17|32|64 * Vendor-Spec iSCSI Node var 641-768 32 16,17|32 * Vendor-Spec FC Port Name var 769-896 64 1|16,17|64 * Vendor-Spec FC Node Name var 897-1024 96 64|96 * Vendor-Specific DDS var 1025-1280 2049 2049 * Vendor-Specific DD var 1281-1536 2065 2065 * Other Vendor-Specific var 1537-2048 vendor-defined DD_Set ID 4 2049 @ 1|32|64|2049|2065 DD_Set Sym Name 4-255 2050 2049 2049 DD_Set Status 4 2051 2049 2049 RESERVED 2052-2064 + DD_ID 4 2065 @|2049 1|32|64|2049|2065 DD_Symbolic Name 4-255 2066 2065 2065 DD_iSCSI Node Index 4 2067 2065 2065 DD_iSCSI Node Member 0-255 2068 2065 2065 DD_iFCP Member (WWPN) 8 2069 2065 2065 RESERVED 2070-2077 DD_Features 4 2078 2065 2065 RESERVED 2304-65535 RESERVED All Others The following is a description of the columns used in the above table: Length - indicates the attribute length in bytes. Variable-length identifiers are NULL character terminated (NULL is included in the length). Tag - the integer tag value used to identify the attribute. All undefined tag values are reserved. Reg Key - indicates the possible tag values for the object key in registration messages for storing a new attribute value. Query Key - indicates the possible tag values for the Message Key and object key that used in the query messages for retrieving a stored value in the iSNS database. Attribute Type (T) -------------------------------------------------------------- # : Required key for object registration ^ : Required key for object registration, unique value is assigned by the iSNS server if value not provided during initial registration. $ : Required as part of the key, and the canonical value is used if one is not registered. & : Attribute required during initial registration Tseng, Gibbons, et al. Standards Track [Page 56] Internet Storage Name Service (iSNS) May 2002 * : Optional to implement. = : Cannot be used as a query key or be explicitly registered. This value is provided by the iSNS server. | : used to separate the different sets of possible keys in the table. % : If an iSCSI Name or FC Port Name WWPN is registered without an EID key, then an Entity will be created and an EID assigned. The assigned EID will be returned in the response as an Operating attribute + : A DD ID is placed into a DD_Set by using the DD_Set ID as the object key attribute 7.2 Entity Identifier-Keyed Attributes The following attributes are stored in the iSNS server using the Entity Identifier attribute as the key. 7.2.1 Entity Identifier (EID) The Entity Identifier is a variable length identifier that uniquely identifies each network entity registered in the iSNS server. The attribute length varies from 4 to 255 bytes, and is a unique value within the iSNS server. If the iSNS client does not provide an EID during registration the iSNS server shall generate one that is unique within the iSNS database. If an EID is to be generated, then the EID attribute value in the registration message shall be empty (0 length). The generated EID shall be returned in the registration response. In environments where the iSNS server is integrated with a DNS infrastructure, the Entity Identifier may be used to store the Fully Qualified Domain Name (FQDN) of the iSCSI or iFCP device. FQDN's of greater than 255 bytes MUST NOT be used. If FQDN's are not used, the iSNS server can be used to generate EIDs. By convention, EIDs generated by the iSNS server begin with the string ôiSNS:ö. iSNS clients MUST NOT generate and register EIDs beginning with the string "iSNS:". 7.2.2 Entity Protocol Entity Protocol is a required 4-byte integer attribute that indicates the protocol of registered network entity. The valid protocol types are defined as below: Tseng, Gibbons, et al. Standards Track [Page 57] Internet Storage Name Service (iSNS) May 2002 Value Entity Protocol Type ----- -------------------- 1 Protocol Neutral 2 iSCSI 3 iFCP All Others RESERVED 'Protocol neutral' is used to indicate that the NETWORK ENTITY does not support an IP block storage protocol. 7.2.3 Management IP Address This field contains the IP Address used to manage the Network Entity and all Storage Nodes contained therein. The Management IP Address is a 16-byte field that may contain either a 32-bit IPv4 or 128-bit IPv6 address. When this field contains an IPv4 value, the most significant 12 bytes are set to 0x00. When this field contains an IPv6 value, the entire 16-byte field is used. If the network entity is capable of being managed and this field is not set, then in-band management through the IP address of one of the Portals of the Network Entity is assumed. 7.2.4 Entity Registration Timestamp This field indicates the most recent time that the entity registration occurred or an associated object attribute was updated or queried by the iSNS client registering the entity. The time format is, in seconds, the update period since the standard base time of 00:00:00 GMT on January 1, 1970. This field cannot be used as a query key or be explicitly registered. 7.2.5 Protocol Version Range This field contains the minimum and maximum version of the protocol supported by the entity. The most significant two bytes contain the maximum version supported, and the least significant two bytes contain the minimum version supported. If a range is not registered then the entity is assumed to support all versions of the protocol. The value 0xffff is a wildcard that indicates no minimum or maximum. If the entity is protocol neutral, then this field SHALL be set to 0. 7.2.6 Registration Period This field indicates the maximum period, in seconds, that the entity registration will be maintained by the server without receipt of an iSNS message from the iSNS client that registered the entity. If the Registration Period is set to 0, then the Entity SHALL NOT be deregistered due to no contact with the iSNS client. If Entity Status Inquiry (ESI) messages are not requested by an entity and the Registration Period is not set to 0, then the entity registration SHALL be removed if an iSNS Protocol message is not received from the iSNS client before the registration period has Tseng, Gibbons, et al. Standards Track [Page 58] Internet Storage Name Service (iSNS) May 2002 expired. Receipt of any iSNS Protocol message from the iSNS client automatically refreshes the Entity Registration Period and Entity Registration Timestamp. To prevent a registration from expiring, the iSNS client should send an iSNS Protocol message to the iSNS server at intervals shorter than the registration period. Such a message can be as simple as a query for one of its own attributes, using its associated iSCSI Name or FC Port Name WWPN as the SOURCE attribute. For an iSNS client that is a NETWORK ENTITY with multiple STORAGE NODE objects, receipt of an iSNS message from any STORAGE NODE of that entity is sufficient to refresh the registration for all STORAGE NODE objects of the entity. Byte 3 and 2 (the least significant bytes) represents the entity registration period, in seconds. Byte 1 and 0 are reserved. If ESI support is requested as part of a portal registration, the ESI Response message received from the iSNS client by the iSNS server SHALL refresh the entity registration. 7.2.7 Entity Index The Entity Index is a 4-byte integer value that uniquely identifies each network entity registered in the iSNS server. The Entity Index is assigned by the iSNS server during the initial registration of an Entity. It can be used to represent a registered entity in situations where the Entity Identifier is too long to be used. 7.2.8 Entity ISAKMP Phase-1 Proposals This field contains the IKE Phase-1 proposal listing in decreasing order of preference the protection suites acceptable to protect all IKE Phase-2 messages sent and received by the Entity. This includes Phase-2 SA's from the iSNS client to the iSNS server as well as to peer iFCP and/or iSCSI devices. This attribute contains the SA payload, proposal payload(s), and transform payload(s) in the ISAKMP format defined in [RFC2408]. This field should be used if the implementer wishes to define a single phase-1 SA security configuration used to protect all phase-2 IKE traffic. If the implementer desires to have a different phase-1 SA security configuration to protect each Portal interface, then the Portal Phase-1 Proposal (section 7.3.10) should be used. 7.2.9 Entity Certificate This attribute contains one or more X.509 certificate that are bound to the NETWORK ENTITY of the iSNS client. This certificate is uploaded and registered to the iSNS server by clients wishing to allow other clients to authenticate themselves and access the services offered by that NETWORK ENTITY. The format of the X.509 certificate is found in [X.509]. Tseng, Gibbons, et al. Standards Track [Page 59] Internet Storage Name Service (iSNS) May 2002 7.3 Portal-Keyed Attributes The following portal attributes are registered in the iSNS database using the combined Portal IP-Address and Portal TCP/UDP Port as the key. Each portal is associated with one Entity Identifier object key. 7.3.1 Portal IP-Address This attribute is the IP address of the PORTAL through which a STORAGE NODE can transmit and receive storage data. When this field contains an IPv4 address, the most significant 12 bytes are set to 0x00. When this field contains an IPv6 address, the entire 16-byte field is used. The Portal IP Address along with the Portal TCP/UDP Port number uniquely identifies a Portal. 7.3.2 Portal TCP/UDP Port The TCP/UDP port of the PORTAL through which a STORAGE NODE can transmit and receive storage data. Bit 16 to 31 represents the TCP/UDP port number. Bit 16 represents the port type. If bit 15 is set, then the port type is UDP. Otherwise it is TCP. Bits 0 to 14 are reserved. If the field value is 0, then the port number is the implied canonical port number and type of the protocol indicated by the associated Entity Type. The Portal IP-Address along with the Portal TCP/UDP Port number uniquely identifies a Portal. 7.3.3 Portal Symbolic Name This is a variable-length text-based value from 0 to 255 bytes. The text field contains user-readable UTF-8 text, and is terminated with at least one NULL character. The Portal Symbolic Name is a user- readable description of the Portal entry in the iSNS server. 7.3.4 Entity Status Inquiry Interval This field indicates the requested time, in seconds, between Entity Status Inquiry (ESI) messages sent from the iSNS server to this entity portal. ESI messages can be used to verify that a Portal registration continues to be valid. To request monitoring by the iSNS server, an iSNS client registers a non-zero value for this portal attribute using a RegDevAttr message. The client must also register an ESI Port on at least one of its Portals to receive the ESI monitoring. If the iSNS server does not receive an expected response to an ESI message, it shall attempt an administratively configured number of re-transmissions of the ESI message. The ESI Interval period begins with the iSNS server's receipt of the last ESI Response. All re- transmissions MUST be sent before twice the ESI Interval period has Tseng, Gibbons, et al. Standards Track [Page 60] Internet Storage Name Service (iSNS) May 2002 passed. If no response is received from any of the ESI messages, then the Portal SHALL be deregistered. If TCP was used to transport the ESI messages, then that TCP connection SHALL be closed. Note that only Portals that have registered a value in their ESI Port field can be deregistered in this way. If all Portals associated with an entity that have registered for ESI messages are deregistered due to non-response, and no registrations have been received from the client for at least two ESI Interval periods, then the entity and all associated objects (including storage nodes) SHALL be deregistered. If the iSNS server is unable to support ESI messages or the ESI Interval requested, it SHALL reject the ESI request by returning an "ESI Not Available" error code. If at any time an iSNS client that is registered for ESI messages has not received an ESI message to any of its portals as expected, then the client MAY attempt to query the iSNS server using a DevAttrQry message using its Entity_ID as the key. If the query result is the error "no such entry", then the client SHALL close all remaining TCP connections to the iSNS server and assume that it is no longer registered in the iSNS database. Such a client MAY attempt re-registration. 7.3.5 ESI Port This field contains the TCP or UDP port of the iSNS client used for ESI monitoring by the iSNS server. Bit 16 to 31 represents the port number. If bit 15 is set, then the port type is UDP. Otherwise, the port is TCP. Bits 0 to 14 are reserved. The iSNS server SHALL return an error if an Entity is registered for ESI monitoring and none of the portals of that Entity has an entry for the ESI Port field. If multiple Portals have a registered ESI port, then the ESI message may be delivered to any of the indicated portals. 7.3.6 Portal Group Tag This field is used to group portals into aggregation groups. The least significant two bytes of this field contain the integer Portal Group Tag value for the Portal. The most significant two bytes are reserved. All Portals MUST be members of a Portal Group. For further details on use of Portal Groups, see [iSCSI]. If a registration message creating a new Portal entry does not contain a Portal Group Tag attribute, or contains the Portal Group Tag attribute with TLV length of 0, then the iSNS server SHALL assign a 16-bit Portal Group Tag value for that Portal that is unique for that Network Entity. The generated Portal Group Tag value shall be returned in the registration response. Tseng, Gibbons, et al. Standards Track [Page 61] Internet Storage Name Service (iSNS) May 2002 7.3.7 Portal Index The Portal Index is a 4-byte integer value that uniquely identifies each portal registered in the iSNS database. The Portal Index is assigned by iSNS server during the initial registration of a portal. The Portal Index can be used to represent a registered portal in situations where the Portal IP-Address and Portal TCP/UDP Port is unwieldy to use. An example of this is when SNMP tables are used to access the contents of the iSNS server. In this case, the Portal Index may be used as the Registered Portal table index. 7.3.8 SCN Port This field contains the TCP or UDP port used by the iSNS client to receive SCN messages from the iSNS server. When a value is registered for this attribute, an SCN message may be received on the indicated port for any of the STORAGE NODEs supported by the Portal. Bit 16 to 31 represents the port number. If bit 15 is set, then the port type is UDP. Otherwise, the port is TCP. Bits 0 to 14 are reserved. The iSNS server SHALL return an error if an SCN registration message is received and none of the portals of the iSNS client has an entry for the SCN Port. If multiple Portals have a registered SCN Port, then the SCN SHALL be delivered to all of the indicated portals. 7.3.9 Portal Security Bitmap This 4-byte field contains flags that indicate security attribute settings for the Portal. Bit 31 (Lsb) of this field must be 1 (enabled) in order for this field to contain significant information. If Bit 31 is enabled, this signifies the iSNS server can be used to store and distribute security policies and settings for iSNS clients (i.e., iSCSI devices). Bit 30 must be 1 in order for bits 25-29 to contain significant information. All other bits are reserved for non-IKE/IPSec security mechanisms to be specified in the future. Bit Field Flag Description --------- ---------------- 25 1 = Tunnel Mode Preferred; 0 = No Preference 26 1 = Transport Mode Preferred; 0 = No Preference 27 1 = PFS Enabled; 0 = PFS Disabled 28 1 = Aggressive Mode Enabled; 0 = Disabled 29 1 = Main Mode Enabled; 0 = MM Disabled 30 1 = IKE/IPSec Enabled; 0 = IKE/IPSec Disabled 31 (Lsb) 1 = Bitmap VALID; 0 = INVALID All others reserved 7.3.10 Portal ISAKMP Phase-1 Proposals This field contains the IKE Phase-1 proposal listing in decreasing order of preference of the protection suites acceptable to protect Tseng, Gibbons, et al. Standards Track [Page 62] Internet Storage Name Service (iSNS) May 2002 all IKE Phase-2 messages sent and received by the Portal. This includes Phase-2 SA's from the iSNS client to the iSNS server as well as to peer iFCP and/or iSCSI devices. This attribute contains the SA payload, proposal payload(s), and transform payload(s) in the ISAKMP format defined in [RFC2408]. This field should be used if the implementer wishes to define phase- 1 SA security configuration on a per-PORTAL basis, as opposed to on a per-NETWORK ENTITY basis. If the implementer desires to have a single phase-1 SA security configuration to protect all phase-2 traffic regardless of the interface used, then the Entity Phase-1 Proposal (section 7.2.8) should be used. 7.3.11 Portal ISAKMP Phase-2 Proposals This field contains the IKE Phase-2 proposal, in ISAKMP format [RFC2408], listing in decreasing order of preference the security proposals acceptable to protect traffic sent and received by the Portal. This field is used only if bits 31, 30 and 29 of the Security Bitmap (see 7.3.9) are enabled. This attribute contains the SA payload, proposal payload(s), and associated transform payload(s) in the ISAKMP format defined in [RFC2408]. 7.3.12 Portal Certificate This attribute contains one or more X.509 certificates that is a credential of the PORTAL. This certificate is used to identify and authenticate communications to the IP address supported by the Portal. The format of the X.509 certificate is specified in [X.509] 7.4 iSCSI Node-Keyed Attributes The following attributes are stored in the iSNS database using the iSCSI Name attribute as the key. Each set of Node-Keyed attributes is associated with one Entity Identifier object key. Although the iSCSI Name key is associated with one Entity Identifier, it is unique across the entire iSNS database. 7.4.1 iSCSI Name This identifier uniquely defines an iSCSI STORAGE NODE, and is a variable-length text-based value from 0 to 255 bytes. This field is required for iSCSI STORAGE NODEs, and is provided by the iSNS client. The registered iSCSI Name MUST be conformant to the format described in [iSCSI] for iSCSI Names. If an iSCSI Name is registered without an EID key, then an Entity will be created and an EID assigned. The assigned EID will be returned in the registration response as an operating attribute. Tseng, Gibbons, et al. Standards Track [Page 63] Internet Storage Name Service (iSNS) May 2002 7.4.2 iSCSI Node Type This required 32-bit field is a bitmap indicating the type of iSCSI STORAGE NODE. The bit fields are defined below. An enabled bit indicates the node has the corresponding characteristics. Bit Field Node Type --------- --------- 29 Control 30 Initiator 31 (Lsb) Target All Others RESERVED If the Target bit is set, then the node represents an iSCSI target. Setting of the Target bit MAY be performed by iSNS clients using the iSNSP. If the Initiator bit is set, then the node represents an iSCSI initiator. Setting of the Initiator bit MAY be performed by iSNS clients using the iSNSP. If the control bit is set, then the node represents a gateway, management station, backup iSNS server, or other device which is not an initiator or target, but requires the ability to send and receive iSNSP messages, including state change notifications. Setting of the control bit is an administrative task that MUST be performed on the iSNS server; iSNS clients SHALL NOT be allowed to change this bit using the iSNSP. This field MAY be used by the iSNS server to distinguish among permissions by different iSCSI node types for accessing various iSNS functions. More than one Node Type bit may be simultaneously enabled. 7.4.3 iSCSI Node Alias This field is a variable-length text-based value from 0 to 255 bytes. The text field contains user-readable UTF-8 text, and is terminated with at least one NULL character. The Alias is a user- readable description of the node entry in the iSNS database. 7.4.4 iSCSI Node SCN Bitmap The iSCSI Node SCN Bitmap indicates those events for which the registering iSNS client wishes to receive a notification message. The following table displays events that result in notifications, and the bit field in the SCN Bitmap that when enabled, results in the corresponding notification. Tseng, Gibbons, et al. Standards Track [Page 64] Internet Storage Name Service (iSNS) May 2002 Note that this field is of dual use--it is used in the SCN registration process to define interested events that will trigger an SCN message, and it is also contained in each SCN message itself, to indicate the type of event that triggered the SCN message. Bit Field Flag Description --------- ---------------- 24 INITIATOR AND SELF INFORMATION ONLY 25 TARGET AND SELF INFORMATION ONLY 26 MANAGEMENT REGISTRATION/SCN 27 OBJECT REMOVED 28 OBJECT ADDED 29 OBJECT UPDATED 30 DD/DDS MEMBER REMOVED (Mgmt Reg/SCN only) 31 (Lsb) DD/DDS MEMBER ADDED (Mgmt Reg/SCN only) All others RESERVED DD/DDS MEMBER REMOVED indicates that an existing member of a Discovery Domain and/or Discovery Domain Set has been removed. DD/DDS MEMBER ADDED indicates that a new member was added to an existing DD and/or DDS. OBJECT REMOVED, OBJECT ADDED, and OBJECT UPDATED indicate a NETWORK ENTITY, PORTAL, STORAGE NODE, FC DEVICE, DD, and/or DDS object was removed, added, or updated in the iSNS database. These flags are not used to indicate a change in the membership of a DD or DDS. Regular SCNs provide information about objects that are updated, added or removed from Discovery Domains that the iSNS client is a member of. An SCN or SCN registration is considered a regular SCN or regular SCN registration if the MANAGEMENT REGISTRATION/SCN flag is cleared. All iSNS clients may register for regular SCN's. Management SCNs provide information about all changes to the network, regardless of discovery domain membership. Registration for management SCN's is indicated by enabling bit 26. Only control nodes may register for management SCN's. Bits 30 and 31 may only be enabled if bit 26 is enabled. TARGET AND SELF INFORMATION ONLY SCN's (bit 25) may be useful for iSCSI initiators. This SCN provides information only about changes to target devices, or if the iSCSI Node itself has undergone a change. Similarly, INITIATOR AND SELF INFORMATION ONLY SCN's (bit 24) may be useful for iSCSI targets, by providing information only about changes to initiator nodes, or the target itself. 7.4.5 iSCSI Node Index The iSCSI Node Index is a 4-byte integer value that uniquely identifies each iSCSI node registered in the iSNS database. The iSCSI Node Index is assigned by the iSNS server during the initial registration of the iSCSI node. Tseng, Gibbons, et al. Standards Track [Page 65] Internet Storage Name Service (iSNS) May 2002 The iSCSI Node Index may be used to represent a registered node in situations where the iSCSI Name is too long to be used. An example of this is when SNMP tables are used to access the contents of the iSNS server. In this case, the iSCSI Node Index may be used as the registered iSCSI Node table index. 7.4.6 WWNN Token This field contains a globally unique 64-bit integer value that can be used to represent the World Wide Node Name of the iSCSI device in a Fibre Channel fabric. This identifier is used during the device registration process, and MUST conform to the requirements in [FC- FS]. The FC-iSCSI gateway uses the value found in this field to register the iSCSI device in the Fibre Channel name server. It is stored in the iSNS server to prevent conflict when assigning "proxy" WWNN values to iSCSI initiators establishing storage sessions to devices in the FC fabric. If the iSNS client does not assign a value for WWNN Token, then the iSNS server SHALL provide a value for this field upon initial registration of the iSCSI node. The process by which the WWNN Token is assigned by the iSNS server MUST conform to the following requirements: 1. The assigned WWNN Token value MUST be unique among all WWN entries in the existing iSNS database, as well as among all devices that can potentially be registered in the iSNS database. 2. Once assigned, the iSNS server MUST persistently save the mapping between the WWNN Token value and registered iSCSI Name. That is, successive re-registrations of the iSCSI node keyed by the same iSCSI Name maintains the original mapping to the associated WWNN Token value in the iSNS server. Similarly, the mapping shall be persistent across iSNS server reboots. Once assigned, the mapping can only be changed if a RegDevAttr message from an authorized iSNS client explicitly provides a different WWNN Token value. 3. Once a WWNN Token value has been assigned and mapped to an iSCSI name, that WWNN Token value SHALL NOT be reused or mapped to any other iSCSI name. 4. The assigned WWNN Token value MUST conform to the formatting requirements of [FC-FS] for World Wide Names (WWN's). An iSNS client, such as an FC-iSCSI gateway or the iSCSI initiator, MAY register its own WWNN Token value or overwrite the iSNS Server- supplied WWNN Token value, if it wishes to supply its own iSCSI-FC name mapping. This is accomplished using the RegDevAttr message with the WWNN Token (tag=37) as an operating attribute. Once overwritten, the new WWNN Token value MUST be stored and saved by the iSNS server, and all requirements specified above continue to Tseng, Gibbons, et al. Standards Track [Page 66] Internet Storage Name Service (iSNS) May 2002 apply. If an iSNS client attempts to register a value for this field that is not unique in the iSNS database or is otherwise invalid, then the registration SHALL be rejected with an error code of 3 (Invalid Registration). There MAY be a matching records in the iSNS database for the Fibre Channel device specified by the WWNN Token. These records for the FC device may contain device attributes for that FC device registered in the Fibre Channel fabric name server. 7.4.7 iSCSI AuthMethod This attribute contains a null-terminated string containing UTF-8 text listing the iSCSI authentication methods enabled for this iSCSI Node, in order of preference. The text values used to identify iSCSI authentication methods are embedded in this string attribute and delineated by a comma. The text values are identical to those found in the main iSCSI draft [iSCSI]; additional vendor-specific text values are also possible. Text Value Description Reference ---------- ----------- --------- KB5 Kerberos V5 RFC 1510 SPKM1 Simple Public Key GSS-API RFC 2025 SPKM2 Simple Public Key GSS-API RFC 2025 SRP Secure Remote Password RFC 2945 CHAP Challenge Handshake Protocol RFC 1994 DH-CHAP Diffie-Hellman Enhanced CHAP none No iSCSI Authentication 7.4.8 iSCSI Node Certificate This attribute contains one or more X.509 certificates that may be a credential used to authenticate the iSCSI node during iSCSI authentication. This certificate MAY be used for the SPKM Public Key authentication method. The format of the X.509 certificate is specified in [X.509]. 7.5 FC Port Name-Keyed Attributes The following attributes are registered in the iSNS database using the FC Port World Wide Name (WWPN) attribute as the key. Each set of FC Port-Keyed attributes is associated with one Entity Identifier object key. Although the FC Port World Wide Name is associated with one Entity Identifier, it is also globally unique. 7.5.1 FC Port Name (WWPN) This 64-bit identifier uniquely defines the FC Port, and is the World Wide Port Name (WWPN) of the corresponding Fibre Channel device. This globally unique identifier is used during the device Tseng, Gibbons, et al. Standards Track [Page 67] Internet Storage Name Service (iSNS) May 2002 registration process, and uses a value conforming to IEEE EUI-64 [EUI-64]. 7.5.2 Port ID (FC_ID) Along with the IP Address, this field uniquely identifies a native Fibre Channel device port in the network, and maps one-to-one to a specific FC Port Name (WWPN) entry. 7.5.3 FC Port Type Indicates the type of FC port. Encoded values for this field are listed in the following table: Type Description ---- ----------- 0x0000 Unidentified/Null Entry 0x0001 Fibre Channel N_Port 0x0002 Fibre Channel NL_Port 0x0003 Fibre Channel F/NL_Port 0x0004-0080 RESERVED 0x0081 Fibre Channel F_Port 0x0082 Fibre Channel FL_Port 0x0083 RESERVED 0x0084 Fibre Channel E_Port 0x0085-00FF RESERVED 0xFF11 mFCP Port 0xFF12 iFCP Port 0xFF13-FFFF RESERVED 7.5.4 Symbolic Port Name A variable-length text-based description of up to 255 bytes, that is associated with the iSNS-registered FC Port Name in the network. The text field contains user-readable UTF-8 text and is terminated with at least one NULL character. 7.5.5 Fabric Port Name (FWWN) This 64-bit identifier uniquely defines the fabric port. If the port of the FC Device is attached to a Fibre Channel fabric port with a registered Port Name, then that fabric Port Name shall be indicated in this field. 7.5.6 Hard Address This field is the requested hard address 24-bit NL Port Identifier, included in the iSNSP for compatibility with Fibre Channel Arbitrated Loop devices and topologies. 7.5.7 Port IP Address The Fibre Channel IP address associated with the FC Port. When an IPv4 value is contained in this field, then the most significant 12 Tseng, Gibbons, et al. Standards Track [Page 68] Internet Storage Name Service (iSNS) May 2002 bytes are set to 0x00. When an IPv6 value is contained in this field, then the entire 16-byte field is used. 7.5.8 Class of Service (COS) This 32-bit bit-map field indicates the Fibre Channel COS types that are supported by the registered port. The COS values are equivalent to Fibre Channel COS values. The valid COS types, and associated bit-map, are listed in the following table: Class of Service Description Bit-Map ---------------- ----------- --------- 2 Delivery Confirmation Provided bit 29 set 3 Delivery Confirmation Not Provided bit 28 set RESERVED other 7.5.9 FC-4 Types This 32-byte field indicates the FC-4 protocol types supported by the associated port. This field can be used to support Fibre Channel devices and is consistent with FC-GS-4. 7.5.10 FC-4 Descriptor A variable-length text-based description of up to 255 bytes, that is associated with the iSNS-registered device port in the network. This field can be used to support Fibre Channel devices and is consistent with FC-GS-4. 7.5.11 FC-4 Features This is a 128-byte array, 4 bits per type, for the FC-4 protocol types supported by the associated port. This field can be used to support Fibre Channel devices and is consistent with FC-GS-4. 7.5.12 iFCP SCN Bitmap This field indicates the events that the iSNS client is interested in. These events can cause SCN to be generated. SCNs provide information about objects that are updated, added or removed from Discovery Domains that the source and destination are a member of. Management SCNs provide information about all changes to the network. Tseng, Gibbons, et al. Standards Track [Page 69] Internet Storage Name Service (iSNS) May 2002 Bit Field Flag Description --------- ---------------- 24 INITIATOR AND SELF INFORMATION ONLY 25 TARGET AND SELF INFORMATION ONLY 26 MANAGEMENT REGISTRATION/SCN 27 OBJECT REMOVED 28 OBJECT ADDED 29 OBJECT UPDATED 30 DD/DDS MEMBER REMOVED (Mgmt Reg/SCN only) 31 (Lsb) DD/DDS MEMBER ADDED (Mgmt Reg/SCN only) All others RESERVED Further information on use of the the above specified bit fields can be found in section 7.4.4. 7.5.13 Port Role This required 32-bit field is a bitmap indicating the type of iFCP STORAGE NODE. The bit fields are defined below. An enabled bit indicates the node has the corresponding characteristics. Bit Field Node Type --------- --------- 29 Control 30 Initiator 31 (Lsb) Target All Others RESERVED If the 'Target' bit is set, then the port represents an FC target. Setting of the 'Target' bit MAY be performed by iSNS clients using the iSNSP. If the 'Initiator' bit is set, then the port represents an FC initiator. Setting of the 'Initiator' bit MAY be performed by iSNS clients using the iSNSP. If the 'Control' bit is set, then the port represents a gateway, management station, iSNS backup server, or other device. This is usually a special device that is neither an initiator nor target, which requires the ability to send and receive iSNSP messages including state change notifications. Setting of the control bit is an administrative task that MUST be administratively configured on the iSNS server; iSNS clients SHALL NOT be allowed to change this bit using the iSNSP. This field MAY be used by the iSNS server to distinguish among permissions by different iSNS clients. For example, an iSNS server implementation may be administratively configured to allow only targets to receive ESI's, or for only control nodes to have permission to add, modify, or delete discovery domains. Tseng, Gibbons, et al. Standards Track [Page 70] Internet Storage Name Service (iSNS) May 2002 7.5.14 Port Certificate This attribute contains one or more X.509 certificates that is a credential of the iFCP STORAGE NODE. The format of the X.509 certificate is found in [X.509]. 7.6 Node-Keyed Attributes The following attributes are registered in the iSNS database using the FC Node Name (WWNN) attribute as the key. Each set of FC Node- Keyed attributes represents a single device, and can be associated with many FC Ports. The FC Node Name is unique across the entire iSNS database. 7.6.1 FC Node Name (WWNN) The FC Node Name is a 64-bit identifier that is the World Wide Node Name (WWNN) of the corresponding Fibre Channel device. This globally unique identifier is used during the device registration process, and uses a value conforming to IEEE EUI-64 [EUI-64]. 7.6.2 Symbolic Node Name A variable-length text-based description of up to 255 bytes, that is associated with the iSNS-registered FC Device in the network. The text field contains user-readable UTF-8 text and is terminated with at least one NULL character. 7.6.3 Node IP Address This IP address is associated with the device node in the network. This field is included for compatibility with Fibre Channel. When an IPv4 value is contained in this field, the most significant 12 bytes are set to 0x00. When an IPv6 value is contained in this field, then the entire 16-byte field is used. 7.6.4 Node IPA This field is the 8 byte Fibre Channel Initial Process Associator (IPA) associated with the device node in the network. The initial process associator is used for communication between Fibre Channel devices. 7.6.5 Node Certificate This attribute contains an X.509 certificate that is bound to the FC Node of the iSNS client. The format of the X.509 certificate is specified in [X.509]. 7.6.6 Proxy iSCSI Name This field contains the iSCSI Name used to represent the FC Node in the IP network. It is used as a pointer to the matching iSCSI Name Tseng, Gibbons, et al. Standards Track [Page 71] Internet Storage Name Service (iSNS) May 2002 entry in the iSNS server. Its value is usually registered by an FC- iSCSI gateway connecting the IP network to the fabric containing the FC device. Note that if this field is used, there SHOULD be a matching entry in the iSNS database for the iSCSI device specified by the iSCSI name. The database entry should include the full range of iSCSI attributes needed for discovery and management of the "iSCSI proxy image" of the FC device. 7.7 Other Attributes The following are not attributes of the previously-defined objects. 7.7.1 FC-4 Type Code This is a 4-byte field, and is used to provide a FC-4 type during a FC-4 Type query. The FC-4 types are consistent with the FC-4 Types as defined in FC-PH. Byte 0 contains the FC-4 type. All other bytes are reserved. 7.7.2 iFCP Switch Name The iFCP Switch Name is a 64-bit World Wide Name (WWN) identifier that uniquely identifies a distinct iFCP gateway in the network. This globally unique identifier is used during the switch registration/switch ID assignment process. The iFCP Switch Name value used MUST conform to the requirements stated in [FC-FS] for World Wide Names. The iSNS server SHALL track the state of all Switch_ID values that have been allocated to each iFCP Switch Name. If a given iFCP Switch Name is deregistered from the iSNS database, then all Switch_ID values allocated to that iFCP Switch Name shall be returned to the unused pool of values. 7.7.3 iFCP Transparent Mode Commands 7.7.3.1 Preferred ID This is a 4-byte unsigned integer field, and is the requested value that the iSNS client wishes to use for the SWITCH_ID. The iSNS server SHALL grant the iSNS client the use of the requested value as the SWITCH_ID, if the requested value has not been already allocated. If the requested value is not available, the iSNS server SHALL return a different value that has not been allocated. 7.7.3.2 Assigned ID This is a 4-byte unsigned integer field that is used by an iFCP gateway to reserve its own unique SWITCH_ID value from the range 1 to 239. When a Switch ID is no longer required, it SHALL be released by the iFCP gateway using the RlseSwId message. The iSNS server MUST use the Entity Status Inquiry message to determine if an iFCP gateway is still present on the network. Tseng, Gibbons, et al. Standards Track [Page 72] Internet Storage Name Service (iSNS) May 2002 7.7.3.3 Space Identifier This is an UTF-8 encoded string. The Space_Identifier string is used as a key attribute to identify a range of non-overlapping SWITCH_ID values to be allocated using RqstSwId. Each Space_Identifier string submitted by iSNS clients shall have its own range of non-overlapping SWITCH_ID values to be allocated to iSNS clients. 7.8 iSNS Server-Specific Attributes Access to the following attributes for through either registration or query messages may be administratively controlled. These attributes are specific to the iSNS server instance; the same value is returned for all iSNS clients accessing the iSNS server. A registration or query for iSNS Server-Specific attribute MUST contain the identifying key attribute (i.e., iSCSI Name or FC Port Name WWPN) of the node originating the registration or query message as the SOURCE and MESSAGE KEY attributes. The operating attributes are the server-specific attributes being registered or queried. 7.8.1 iSNS Server Vendor OUI This attribute is the OUI (Organizationally Unique Identifier) [802- 1990] identifying the specific vendor implementing the iSNS server. This attribute can only be queried; iSNS clients SHALL NOT be allowed to register a value for the iSNS Server Vendor OUI. 7.9 Discovery Domain Registration Attributes 7.9.1 DD Set ID Keyed Attributes 7.9.1.1 Discovery Domain Set ID (DDS ID) The DDS ID is a unique unsigned integer identifier used in the iSNS directory database to indicate a Discovery Domain Set. A DDS is a collection of Discovery Domains that can be enabled or disabled by a management station. This value is used as a key for DDS attribute queries. When a Discovery Domain is registered it is initially not in any DDS. If the iSNS client does not provide a DDS_ID in a DDS registration request message, the iSNS server shall generate a DDS_ID value that is unique within the iSNS database for that new DDS. The created DDS ID shall be returned in the response message. The DDS ID value of 0 is reserved. 7.9.1.2 Discovery Domain Set Symbolic Name The DDS_Symbolic Name is a UTF-8, variable-length, NULL-terminated string. This is an user-readable field used to assist a network administrator in tracking the DDS function. When registered by a client, the DDS symbolic name SHALL be verified unique by the iSNS Tseng, Gibbons, et al. Standards Track [Page 73] Internet Storage Name Service (iSNS) May 2002 server. If the DDS symbolic name is not unique, then the DDS registration SHALL be rejected with an ôInvalid Registrationö error code. The invalid attribute(s), in this case the DDS symbolic name, SHALL be included in the response. 7.9.1.3 Discovery Domain Set Status The DDS_Status field is a 32-bit bitmap indicating the status of the DDS. Bit 0 of the bitmap indicates whether the DDS is Enabled (1) or Disabled (0). The default value for the DDS Enabled flag is Disabled (0). Bit Field DDS Status --------- --------- 31 (Lsb) DDS Enabled (1) / DDS Disabled (0) All Others RESERVED 7.9.2 DD ID Keyed Attributes 7.9.2.1 Discovery Domain ID (DD ID) The DD ID is a unique unsigned integer identifier used in the iSNS directory database to indicate the DD. This value is used as the key for any DD attribute query. If the iSNS client does not provide a DD_ID in a DD registration request message, the iSNS server shall generate a DD_ID value that is unique within the iSNS database for that new DD (i.e., the iSNS client will be registered in a new DD). The created DD ID shall be returned in the response message. The DD ID value of 0 is reserved. 7.9.2.2 Discovery Domain Symbolic Name The DD_Symbolic Name is a UTF-8 encoded, variable-length, NULL- terminated string. When registered by a client, the DD symbolic name SHALL be verified unique by the iSNS server. If the DD symbolic name is not unique, then the DD registration SHALL be rejected with an ôInvalid Registrationö error code. The invalid attribute(s), in this case the DD symbolic name, SHALL be included in the response. 7.9.2.3 Discovery Domain iSCSI Node Index This is the iSCSI Node Index of an iSNS client that is a member of the DD. The DD may have a list of 0 to n members. The iSCSI Node Index is one alternative representation of membership in a Discovery Domain, the other alternative being the iSCSI Name. The Discovery Domain iSCSI Node Index is a 4-byte integer value. The iSCSI Node Index can be used to represent a DD member in situations where the iSCSI Name is too long to be used. An example of this is when SNMP tables are used to access the contents of the iSNS server. Tseng, Gibbons, et al. Standards Track [Page 74] Internet Storage Name Service (iSNS) May 2002 The iSCSI Node Index and iSCSI Name stored as a member in a DD SHALL be consistent with the iSCSI Node Index and iSCSI Name attributes registered for the STORAGE NODE object in the iSNS server. 7.9.2.4 Discovery Domain Member--iSCSI Name This attribute indicates membership for an iSCSI STORAGE NODE in the Discovery Domain. There is no limit to the number of members that may be in a DD. Membership is represented by the iSCSI Name of the iSCSI STORAGE NODE. 7.9.2.5 Discovery Domain Member--FC Port Name This attribute indicates membership for an iFCP STORAGE NODE (FC Port) in the Discovery Domain . There is no limit to the number of members that may be in a DD. Membership is represented by the FC Port Name (WWPN) of the iFCP STORAGE NODE. 7.9.2.6 Discovery Domain Features The Discovery Domain Features is a bitmap indicating the features of this DD. The bit fields are defined below. An enabled bit indicates the DD has the corresponding characteristics. Bit Field DD Feature --------- ---------- 31 (Lsb) Boot List All Others RESERVED Boot List: this feature indicates that the targets in this DD provide boot capabilities for the member initiators, as described in [iSCSI-boot]. 7.10 Vendor-Specific Attributes Specific iSNS server implementations MAY define vendor-specific attributes for private use. The tag values reserved for vendor- specific and user-specific use are defined in section 7.1. To avoid misinterpreting proprietary attributes, it is RECOMMENDED that the vendor's own OUI (Organizationally Unique Identifier) be placed in the upper three bytes of the attribute field itself. If the OUI is not used, then some other unique marker recognizable by the vendor SHOULD be used. The OUI is defined in IEEE Std 802-1990, and is the same constant used to generate 48 bit Universal LAN MAC addresses. A vendor's own iSNS implementation will then be able to recognize the OUI in the vendor-specific or user-specific attribute field, and be able to execute vendor-specific handling of the attribute. 7.10.1 Vendor-Specific Server Attributes Attributes with tags in the range 257 to 384 are vendor-specific or site-specific attributes of the iSNS server. Registration and/or query access to these attribute may be administratively controlled. These attributes are unique for each logical iSNS server instance. Tseng, Gibbons, et al. Standards Track [Page 75] Internet Storage Name Service (iSNS) May 2002 Query and registration messages for these attributes SHALL use the key identifier (i.e., iSCSI Name or FC Port Name WWPN) for both the SOURCE attribute and MESSAGE KEY attribute. 7.10.2 Vendor-Specific Entity Attributes Attributes in the range 385 to 512 are vendor-specific or site- specific attributes used to describe the Entity object. These attributes are keyed by the Entity Identifier attribute (tag=1). 7.10.3 Vendor-Specific Portal Attributes Attributes in the range 513 to 640 are vendor-specific or site- specific attributes used to describe the Portal object. These attributes are keyed by the Portal IP-Address (tag=16) and Portal TCP/UDP Port (tag=17). 7.10.4 Vendor-Specific iSCSI Node Attributes Attributes in the range 641 to 768 are vendor-specific or site- specific attributes used to describe the iSCSI Node object. These attributes are keyed by the iSCSI Name (tag=32). 7.10.5 Vendor-Specific FC Port Name Attributes Attributes in the range 769 to 896 are vendor-specific or site- specific attributes used to describe the N_Port Port Name object. These attributes are keyed by the FC Port Name WWPN (tag=64). 7.10.6 Vendor-Specific FC Node Name Attributes Attributes in the range 897 to 1024 are vendor-specific or site- specific attributes used to describe the FC Node Name object. These attributes are keyed by the FC Node Name WWNN (tag=96). 7.10.7 Vendor-Specific Discovery Domain Attributes Attributes in the range 1025 to 1280 are vendor-specific or site- specific attributes used to describe the Discovery Domain object. These attributes are keyed by the DD_ID (tag=104). 7.10.8 Vendor-Specific Discovery Domain Set Attributes Attributes in the range 1281 to 1536 are vendor-specific or site- specific attributes used to describe the Discovery Domain Set object. These attributes are keyed by the DD Set ID (tag=101) 7.10.9 Other Vendor-Specific Attributes Attributes in the range 1537 to 2048 can be used for key and non-key attributes that describe new vendor-specific objects specific to the vendor's iSNS server implementation. Tseng, Gibbons, et al. Standards Track [Page 76] Internet Storage Name Service (iSNS) May 2002 7.11 Standards-Based Extensions These attributes are reserved for future work by other standards bodies. 8. Security Considerations 8.1 iSNS Security Threat Analysis When the iSNS protocol is deployed, the interaction between iSNS server and iSNS clients are subject to the following security threats: [1] An attacker could alter iSNS protocol messages, such as to direct iSCSI and iFCP devices to establish connections with rogue peer devices, or to weaken/eliminate IPSec protection for iSCSI or iFCP traffic. [2] An attacker could masquerade as the real iSNS server using false iSNS heartbeat messages. This could cause iSCSI and iFCP devices to use rogue iSNS servers. [3] An attacker could gain knowledge about iSCSI and iFCP devices by snooping iSNS protocol messages. Such information could aid an attacker in mounting a direct attack on iSCSI and iFCP devices, such as a denial-of-service attack or outright physical theft. To address these threats, the following capabilities are needed: [a] Unicast iSNS protocol messages may need to be authenticated. In addition, to protect against threat [3] above, confidentiality support is desirable, and REQUIRED when certain functions of iSNS server are utilized. [b] Multicast iSNS protocol messages such as the iSNS heartbeat message may need to be authenticated. These messages need not be confidential since they do not leak critical information. 8.2 iSNS Security Implementation and Usage Requirements If the iSNS server is used to distribute authorizations for communications between iFCP and iSCSI peer devices, IPsec ESP with null transform MUST be implemented, and non-null transform MAY be implemented. If a non-null transform is implemented, then the DES encryption algorithm MUST NOT be used. If the iSNS server is used to distribute security policy for iFCP and iSCSI devices, then authentication, data integrity, and confidentiality must be supported and used. Where confidentiality is desired or required, IPsec ESP with non-null transform SHOULD be used, and the DES encryption algorithm MUST NOT be used. In order to protect against an attacker masquerading as an iSNS server, client devices must support the ability to authenticate Tseng, Gibbons, et al. Standards Track [Page 77] Internet Storage Name Service (iSNS) May 2002 broadcast or multicast messages such as the iSNS heartbeat. The iSNS authentication block (which is identical in format to the SLP authentication block) may be used for this purpose. Note that the authentication block is used only for iSNS broadcast or multicast messages, and SHOULD NOT be used in unicast iSNS messages. There is no requirement that the communicating identities in iSNS protocol messages be kept confidential. Specifically, the identity and location of the iSNS server shall not be considered confidential. For protecting unicast iSNS protocol messages, iSNS servers supporting security MUST implement ESP in tunnel mode and MAY implement transport mode. All iSNS implementations supporting security MUST support the replay protection mechanisms of IPsec. iSNS security implementations MUST support both IKE Main Mode and Aggressive Mode for authentication, negotiation of security associations, and key management, using the IPSec DOI [RFC2407]. Manual keying SHOULD NOT be used since it does not provide the necessary rekeying support. Conformant iSNS security implementations MUST support authentication using a pre-shared key, and MAY support certificate-based peer authentication using digital signatures. Peer authentication using the public key encryption methods outlined in IKE's sections 5.2 and 5.3 [RFC2409] SHOULD NOT be supported. Conformant iSNS implementations MUST support both IKE Main Mode and Aggressive Mode. IKE Main Mode with pre-shared key authentication SHOULD NOT be used when either of the peers use dynamically assigned IP addresses. While Main Mode with pre-shared key authentication offers good security in many cases, situations where dynamically assigned addreses are used force the use a group pre-shared key, which is vulnerable to man-in-the-middle attack. IKE Identity Payload ID_KEY_ID MUST NOT be used. When digital signatures are used for authentication, either IKE Main Mode or IKE Aggressive Mode MAY be used. In all cases, access to locally stored secret information (pre-shared key or private key for digital signing) MUST be suitably restricted, since compromise of the secret information nullifies the security properties of the IKE/IPsec protocols. When digital signatures are used to achieve authentiation, an IKE negotiator SHOULD use IKE Certificate Request Payload(s) to specify the certificate authority (or authorities) that are trusted in accordance with its local policy. IKE negotiators SHOULD check the pertinent Certificate Revocation List (CRL) before accepting a PKI certificate for use in IKE's authentication procedures. When the iSNS server is used without security, IP block storage protocol implementations MUST support a negative cache for Tseng, Gibbons, et al. Standards Track [Page 78] Internet Storage Name Service (iSNS) May 2002 authentication failures. This allows implementations to avoid continually contacting discovered endpoints that fail authentication within IPsec or at the application layer (in the case of iSCSI Login). The negative cache need not be maintained within the IPsec implementation, but rather within the IP block storage protocol implementation. 8.3 Discovering Security Requirements of Peer Devices Once communication between iSNS clients and the iSNS server have been secured through use of IPSec, the iSNS client devices have the capability to discover the security settings that they need to use for their peer-to-peer communications using the iSCSI and/or iFCP protocols. This provides a potential scaling advantage over device- by-device configuration of individual security policies for each iSCSI and iFCP device. The iSNS server stores security settings for each iSCSI and iFCP device interface. These security settings, which can be retrieved by authorized hosts, include use or non-use of IPSec, IKE, Main Mode, and Aggressive Mode. For example, IKE may not be enabled for a particular interface of a peer device. If a peer device can learn of this in advance by consulting the iSNS server, it will not need to waste time and resources attempting to initiate an IKE phase 1 session with that peer device interface. If iSNS is used for this purpose, then the minimum information that should be learned from the iSNS server is the use or non-use of IKE and IPSec by each iFCP or iSCSI peer device interface. This information is encoded in the Security Bitmap field of each Portal of the peer device, and is applicable on a per-interface basis for the peer device. iSNS queries to acquire security configuration data about peer devices MUST be protected by IPSec/ESP authentication. 8.4 Configuring Security Policies of iFCP/iSCSI Devices Use of iSNS for distribution of security policies offers the potential to reduce the burden of manual device configuration, and decrease the probability of communications failures due to incompatible security policies. If iSNS is used to distribute security policies, then IPSec authentication, data integrity, and confidentiality MUST be used to protect all iSNS protocol messages. The complete IKE/IPSec configuration of each iFCP and/or iSCSI device can be stored in the iSNS server, including policies that are used for IKE Phase 1 and Phase 2 negotiations between client devices. The IKE payload format includes a series of one or more proposals that the iSCSI or iFCP device will use when negotiating the appropriate IPsec policy to use to protect iSCSI or iFCP traffic. In addition, the iSCSI Authentication Methods used by each iSCSI device can also be stored in the iSNS server. The iSCSI AuthMethod Tseng, Gibbons, et al. Standards Track [Page 79] Internet Storage Name Service (iSNS) May 2002 field (tag=42) contains a null-terminated string embedded with the text values indicating iSCSI authentication methods to be used by that iSCSI device. Note that iSNS distribution of security policy is not necessary if the security settings can be determined by other means, such as manual configuration or IPsec security policy distribution. If an entity has already obtained its security configuration via other mechanisms, then it MUST NOT request security policy via iSNS. For further details on how to store and retrieve IKE policy proposals in the iSNS server, see [58]. 8.5 Resource Issues The iSNS protocol is lightweight, and will not generate a significant amount of traffic. iSNS traffic is characterized by occassional registration, notification, and update messages that do not consume significant amounts of bandwidth. Even software-based IPSec implementations should not have a problem handling the traffic loads generated by the iSNS protocol. To fulfill iSNS security requirements, the only additional resources needed beyond what is already required for iSCSI and iFCP involves the iSNS server. Since iSCSI and iFCP end nodes are already required to implement IKE and IPSec, these existing requirements can also be used to fulfill IKE and IPSec requirements for iSNS clients. 8.6 iSNS Interaction with IKE and IPSec When IPSec security is enabled, each iSNS client that is registered in the iSNS database SHALL maintain at least one phase-1 and one phase-2 security association with the iSNS server. All iSNS protocol messages between iSNS clients and the iSNS server SHALL be protected by a phase-2 security association. When an iSNS client is removed from the iSNS database, the iSNS server shall send a phase-1 delete message to the associated IKE peer, and tear down all phase-1 and phase-2 SA's associated with that iSNS client. Tseng, Gibbons, et al. Standards Track [Page 80] Internet Storage Name Service (iSNS) May 2002 9. Normative References [iSCSI] Satran, J., et al., "iSCSI", Internet draft (work in progress), draft-ietf-ips-iSCSI-09.txt, November 2001 [iFCP] Monia, C., et al., "iFCP - A Protocol for Internet Fibre Channel Storage Networking", Internet draft (work in progress), draft-ietf-ips-ifcp-07.txt, November 2001 [RFC2608] Guttman, E., Perkins, C., Veizades, J., Day, M., "Service Location Protocol, Version 2", RFC 2608, June 1999 [iSCSIName] Bakke, M., et al., "iSCSI naming and Discovery", draft- ietf-ips-iscsi-name-disc-03.txt, November 2001 [iSCSI-SLP] Bakke, M., "Finding iSCSI Targets and Name Servers Using SLP", Internet draft (work in progress), draft-ietf-ips- iscsi-slp-01.txt, July 2001 [RFC2119] Bradner, S., "Key Words for Use in RFCs to Indicate Requirement Levels, BCP 14, RFC 2119, March 1997 [SEC-IPS] Aboba, B., et al., "Securing IP Block Storage Protocols", draft-ietf-ips-security-07.txt, December 2001 [RFC2401] Atkinson, R., Kent, S., "Security Architecture for the Internet Protocol", RFC 2401, November 1998 [RFC2406] Kent, S., Atkinson, R., "IP Encapsulating Security Payload (ESP)", RFC 2406, November 1998 [RFC2407] Piper, D., "The Internet IP Security Domain of Interpretation of ISAKMP", RFC 2407, November 1998 [RFC2408] Maughan, D., Schertler, M., Schneider, M., Turner, J., "Internet Security Association and Key Management Protocol (ISAKMP), RFC 2408, November 1998 [RFC2409] Harkins, D., Carrel, D., "The Internet Key Exchange (IKE)", RFC 2409, November 1998 [RFC2412] Orman, H., "The OAKLEY Key Determination Protocol", RFC 2412, November 1998 [RFC793] Postel, J., "Transmission Control Protocol", STD 7, RFC 793, September 1981 [DSS] FIPS PUB 186-2, National Institute of Standards and Technology, Digital Signature Standard (DSS), Technical Report Tseng, Gibbons, et al. Standards Track [Page 81] Internet Storage Name Service (iSNS) May 2002 [EUI-64] Guidelines for 64-bit Global Identifier (EUI-64) Registration Authority, May 2001, IEEE, http://standards.ieee.org/regauth/oui/tutorials/EUI64.ht ml [X.509] ITU-T Recommendation X.509 (1997 E): Information Technology - Open Systems Interconnection - The Directory: Authentication Framework, June 1997 [802-1990] IEEE Standards for Local and Metropolitan Area Networks: Overview and Architecture, Technical Committee on Computer Communications of the IEEE Computer Society, May 31, 1990 [FC-FS] Fibre Channel Framing and Signaling Interface, NCITS Working Draft Project 1331-D 10. Informative References [RFC1035] Mockapetris, P., "Domain Names - Implementation and Specification, RFC 1035, November 1987 [RFC1305] Mills, D., Network Time Protocol (Version 3), RFC 1305, March 1992 [FC-GS] Fibre Channel Generic Services, ANSI X3.288:1996 [FC-GS-2] Fibre Channel Generic Services-2, ANSI NCITS 288 [FC-GS-3] Fibre Channel Generic Services-3, NCITS 348-2000 [FC-GS-4] Fibre Channel Generic Services-4, NCITS Working Draft Project 1505-D [RFC2026] Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 Tseng, Gibbons, et al. Standards Track [Page 82] Internet Storage Name Service (iSNS) November 2001 11. Author's Addresses Josh Tseng Nishan Systems 3850 North First Street San Jose, CA 95134-1702 Phone: (408) 519-3749 Email: jtseng@nishansystems.com Kevin Gibbons Nishan Systems 3850 North First Street San Jose, CA 95134-1702 Phone: (408) 519-3756 Email: kgibbons@nishansystems.com Franco Travostino Nortel Networks 3 Federal Street Billerica, MA 01821 Phone: 978-288-7708 Email: travos@nortelnetworks.com Curt Du Laney IBM 4205 South Miami Blvd Research Triangle Park, NC 27709 Email: dulaney@us.ibm.com Phone: (919) 254-5632 Joe Souza Microsoft Corporation One Microsoft Way Redmond, WA 98052-6399 Email: joes@microsoft.com Phone: (425) 706-3135 Gibbons, Tseng, Monia Standards Track [Page 83] Internet Storage Name Service (iSNS) November 2001 Full Copyright Statement "Copyright (C) The Internet Society (date). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." Tseng, Gibbons, et al. Standards Track [Page 84] Internet Storage Name Service (iSNS) November 2001 Appendix A -- iSNS Examples A.1 iSCSI Initialization Example This example assumes an SLP Service Agent (SA) has been implemented on the iSNS host, and an SLP User Agent (UA) has been implemented on the iSNS initiator. See [RFC2608] for further details on SA's and UA's. This example also assumes the target is configured to use the iSNS server, and have its access control policy subordinated to the iSNS server. A.1.1 Simple iSCSI Target Registration In this example, a simple target with a single iSCSI name registers with the iSNS server. The target has not been assigned a Fully Qualified Domain Name (FQDN) by the administrator. +--------------------------+------------------+-------------------+ | iSCSI Target Device | iSNS Server |Management Station | +--------------------------+------------------+-------------------+ |Discover iSNS--SLP------->| |/*mgmt station is | | |<--SLP--iSNS Here:| administratively | | | 192.36.53.1 | authorized to view| | | | all DD's. Device | | | | NAMEabcd has been | | RegDevAttr--------->| | previously placed | |Oper Attrs: | | into DDabcd******/| |tag=1: NULL | | | |tag=2: "iSCSI" | | | |tag=16: "192.36.4.5" | | | |tag=17: "5001" | | | |tag=19: 0 | | | |tag=32: "NAMEabcd" | | | |tag=33: "target" | | | |tag=34: "disk 1" | | | | |<---RegDevAttrRsp | | | |SUCCESS | | | |tag=1: "iSNS:0001"| | | |tag=16: "192.36.4.5" | | |tag=17: "5001" | | | |tag=32: "NAMEabcd"| | | | | | | DevAttrQry--------->| SCN-------->| | |Src:(tag=32) "NAMEabcd" |(or SNMP trap) | | |Key:(tag=2) "iSCSI" |tag=1: "iSNS:0001" | |Key:(tag=33) "initiator" |dest: "mgmt.foo.com" | |Oper Attrs: |CHANGE IN NETWORK | | |tag=16: NULL | | | |tag=17: NULL | |<-------SCNRsp | |tag=32: NULL | | | |/*Query asks for all iSCSI| | | |devices' IP address, port |<---DevAttrQryRsp | | |number, and Name*/ |SUCCESS | | | |tag=16:"192.36.4.1" | Tseng, Gibbons, et al. Standards Track [Page 85] Internet Storage Name Service (iSNS) November 2001 | |tag=17:"50000" | | | |tag=32:"devpdq" | | | |tag=16:"192.1.3.2"|<-----DevAttrQry | | |tag=17:"50000" |src: ôMGMTname1ö | | |tag=32:"devrst" |key:(tag=1)iSNS:0001 | | |Op Attrs: | |/*************************| |tag=16: NULL | |Our target "iSNS:0001" | |tag=17: NULL | |discovers two initiators | |tag=32: NULL | |in the same DD. It will | | | |accept iSCSI logins from | | | |these two identified | | | |initiators presented by | | | |iSNS*********************/| DevAttrQryRsp--->| | | |SUCCESS | | | |tag=16: 192.36.4.5| | | |tag=17: 5001 | | | |tag=32: NAMEabcd | | +--------------------------+------------------+-------------------+ A.1.2 Target Registration and DD Configuration In this example, a more complex target registers with the iSNS. This target has been configured with a Fully Qualified Domain Name (FQDN) in the DNS servers, and the user wishes to use this identifier for the device. Also, the user wishes to use public key certificates in the iSCSI login authentication. +--------------------------+------------------+-------------------+ | iSCSI Target Device | iSNS Server |Management Station | +--------------------------+------------------+-------------------+ |Discover iSNS--SLP--> | |/*mgmt station is | | |<--SLP--iSNS Here:| administratively | | | 192.36.53.1 | authorized to view| | RegDevAttr--> | | all DD's ********/| |Oper Attrs: | | | |tag=1: "jbod1.foo.com" | | | |tag=2: "iSCSI" | | | |tag=16: "192.36.34.4" | | | |tag=17: "5001" | | | |tag=19: "5 seconds" | | | |tag=16: "192.36.53.5" | | | |tag=17: "5001" | | | |tag=32: "NAMEabcd" | | | |tag=33: "Target" |/*****************| | |tag=34: "Storage Array 1" |jbod1.foo.com is | | |tag=43: X.509 cert |now registered in | | |tag=32: "NAMEefgh" |iSNS, but is not | | |tag=33: "Target" |in any DD. Therefore, | |tag=34: "Storage Array 2" |no other devices | | |tag=43: X.509 cert |can "see" it. | | | |*****************/| | | |<--RegDevAttrRsp | | Tseng, Gibbons, et al. Standards Track [Page 86] Internet Storage Name Service (iSNS) November 2001 | |SUCCESS | | | |tag=1: "jbod1.foo.com" | | |tag=16: "192.36.34.4" | | |tag=17: "5001" | | | |tag=16: "192.36.53.5" | | |tag=17: "5001" | | | |tag=32: "NAMEabcd"| | | |tag=32: "NAMEefgh"| | | | | | | | SCN------> | | | | (or SNMP trap) | | | |tag=1: jbod1.foo.com | | |dest: mgmt.foo.com| | | |CHANGE IN NETWORK | | | | | | | | |<--SCNRsp | | | |<--DevAttrQry | | | |src: mgmt.foo.com | | | |key: (tag=1) | | | | jbod1.foo.com | | | |Op Attr: (tag=2) | | | |Op Attr: (tag=16) | | | |Op Attr: (tag=17) | | | |Op Attr: (tag=32) | | | | | | | DevAttrQryRsp--> | | | |SUCCESS | | | |tag=2: "iSCSI" | | | |tag=16: 192.36.34.4 | | |tag=17: 5001 | | | |tag=16: 192.36.53.5 | | |tag=17: 5001 |/**Mgmt Station ***| | |tag=32:"NAMEabcd" |displays device, | | |tag=32:"NAMEefgh" |the operator decides | | |to place "NAMEabcd"| | | |into Domain "DDxyz"| |/*************************| |******************/| |Target is now registered | | | |in iSNS. It has been placed |<--DDReg | |in DDxyz by management | |src: "mgmt.foo.com"| |station. | |key: "DDxyz ID" | |*************************/| |Op Attr: | | | |tag=32: "NAMEabcd" | | | DDRegRsp----->| | | | SUCCESS | | +--------------------------+------------------+-------------------+ A.1.3 Initiator Registration and Target Discovery The following example illustrates a new initiator registering with the iSNS, and discovering the target NAMEabcd from the example in A.1.2. Tseng, Gibbons, et al. Standards Track [Page 87] Internet Storage Name Service (iSNS) November 2001 +--------------------------+------------------+-------------------+ | iSCSI Initiator | iSNS |Management Station | +--------------------------+------------------+-------------------+ |Discover iSNS--SLP--> | |/*mgmt station is | | |<--SLP--iSNS Here:| administratively | | | 192.36.53.1 | authorized to view| |RegDevAttr--> | | all DD's ********/| |Oper Attrs: | | | |tag=1: "svr1.foo.com" | | | |tag=2: "iSCSI" | | | |tag=16: "192.20.3.1" |/*****************| | |tag=17: "5001" |Device not in any | | |tag=19: 5 seconds |DD, so it is | | |tag=32: "NAMEijkl" |inaccessible by | | |tag=33: "Initiator" |other devices | | |tag=34: "Server1" |*****************/| | |tag=43: X.509 certificate | | | | |<--RegDevAttrRsp | | | |SUCCESS | | | |tag=1: "svr1.foo.com" | | |tag=16: "192.20.3.1" | | |tag=17: "5001" | | | |tag=32: "NAMEijkl"| | | | | | | | SCN------> | | | | (or SNMP trap) | | | |tag=1: svr1.foo.com | | |dest: mgmt.foo.com| | | |CHANGE IN NETWORK | | | | | | | | |<------SCNRsp | | | |<----DevAttrQry | | | |src: mgmt.foo.com | | | |key: (tag=1) | | | | svr1.foo.com | | | |Op Attr: (tag=2) | | | |Op Attr: (tag=16) | | | |Op Attr: (tag=17) | | | |Op Attr: (tag=32) | | | DevAttrQryRsp--> | | | |SUCCESS | | | |tag=2: "iSCSI" | | | |tag=16:192.20.3.1 | | | |tag=17: "5001" | | | |tag=32:"NAMEijkl" | | | | |/**Mgmt Station ***| | | |displays device, | | | |the operator decides | | |to place "NAMEijkl"| | | |into Domain "DDxyz"| | | |with device NAMEabcd | | |******************/| | | |<--DDReg | | | |src: (tag=1) | Tseng, Gibbons, et al. Standards Track [Page 88] Internet Storage Name Service (iSNS) November 2001 | | | "mgmt.foo.com" | | | |key: "DDxyz ID" | | | |tag=32: "NAMEijkl | | | | | | | DDRegRsp---->|/******************| | | SUCCESS |"NAMEijkl" has been| | | |moved to "DDxyz" | | | |******************/| | |<-----SCN | | | |tag=32: "NAMEijkl"| | | |CHANGE IN DD MEMBERSHIP | | DevAttrQry----------->| | | |src: "NAMEabcd" |/*****************| | |key:(tag=2) "iSCSI" |Note that NAMEabcd| | |key:(tag=33) "Target" |also receives an | | |Op Attr: (tag=16) |SCN that NAMEijkl | | |Op Attr: (tag=17) |is in the same DD | | |Op Attr: (tag=32) |*****************/| | |Op Attr: (tag=34) | | | |Op Attr: (tag=43) |<-----AttrQryRsp | | | |SUCCESS | | | |tag=16: 192.36.34.4 | | |tag=17: 5001 | | | |tag=16: 192.36.53.5 | | |tag=17: 5001 | | | |tag=32: NAMEabcd | | | |tag=34: Volume 1 | | | |tag=43: X.509 cert| | | | | | |/***The initiator has discovered | | |the target, and has everything | | |needed to complete iSCSI login | | |The same process occurs on the | | |target side; the SCN prompts the | | |target to download the list of | | |authorized initiators from the | | |iSNS (i.e., those initiators in the | | |same DD as the target.************/ | | +--------------------------+------------------+-------------------+ Tseng, Gibbons, et al. Standards Track [Page 89]