Network Working Group M. Boucadair Internet-Draft France Telecom Intended status: Standards Track R. Penno Expires: April 11, 2011 Juniper Networks D. Wing Cisco October 08, 2010 UPnP IGD-PCP Interworking Function draft-bpw-pcp-upnp-igd-interworking-00 Abstract This document specifies the behavior of the UPnP IGD (Internet Gateway Device)/PCP interworking function. An UPnP IGD-PCP Interworking function is required to be embedded in CP routers to allow for transparent NAT control in environments where UPnP is used in the LAN side and PCP in the external side of the CP router. Requirements Language 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 RFC 2119 [RFC2119]. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on April 11, 2011. Copyright Notice Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved. Boucadair, et al. Expires April 11, 2011 [Page 1] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Overall Context . . . . . . . . . . . . . . . . . . . . . 3 1.2. Purpose of this Document . . . . . . . . . . . . . . . . . 3 2. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Architecture Model . . . . . . . . . . . . . . . . . . . . . . 4 4. UPnP IGD-PCP Interworking Function: Overview . . . . . . . . . 6 5. Specification of the IGD-PCP Interworking Function . . . . . . 10 5.1. PCP Server Discovery . . . . . . . . . . . . . . . . . . . 10 5.2. Control of the Firewall . . . . . . . . . . . . . . . . . 11 5.3. NAT Control in LAN Side . . . . . . . . . . . . . . . . . 11 5.4. Port Mapping Tables . . . . . . . . . . . . . . . . . . . 11 5.5. Interworking Function Without NAT in the CP Router . . . . 11 5.6. NAT Embedded in the CP Router . . . . . . . . . . . . . . 12 5.7. Creating a Mapping . . . . . . . . . . . . . . . . . . . . 13 5.8. Listing One or a Set of Mappings . . . . . . . . . . . . . 19 5.9. Delete One or a Set of Mappings . . . . . . . . . . . . . 20 5.10. Mapping Synchronisation . . . . . . . . . . . . . . . . . 20 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 7. Security Considerations . . . . . . . . . . . . . . . . . . . 21 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21 9.1. Normative References . . . . . . . . . . . . . . . . . . . 21 9.2. Informative References . . . . . . . . . . . . . . . . . . 22 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22 Boucadair, et al. Expires April 11, 2011 [Page 2] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 1. Introduction 1.1. Overall Context PCP [I-D.wing-softwire-port-control-protocol] discusses the implementation of NAT control features that rely upon Provider NAT devices such as DS-Lite AFTR [I-D.ietf-softwire-dual-stack-lite] or NAT64 [I-D.ietf-behave-v6v4-xlate-stateful]. Nevertheless, in environments where UPnP is used in the home LAN, an interworking function between UPnP IGD and PCP is required to be embedded in the CP router (an example is illustrated in Figure 1). UPnP-PCP UPnP Control Interworking Point Function PCP Server | | | | (1) AddPortMapping | | |--------------------->| | | |(2) PCP Map Create Request| | |------------------------->| | | | Figure 1: Flow Example This specification takes into account the requirements identified in PCP base document, particularly it avoids chatty exchanges (e.g., in case of invoking AddPortMapping()) and prevents against overload phenomena (e.g., avalanche restart). The UPnP IGD-PCP Interworking Function maintains a local mapping table which stores all active mappings instructed by internal UPnP Control Points. This design choice restricts the amount of PCP messages to be exchanged with the PCP Server. Triggers for deactivating the UPnP IGD-PCP Interworking Function from the CP router and relying on a PCP-only mode are out of scope of this document. 1.2. Purpose of this Document The objective of this document is to specify a UPnP IGD-PCP Interworking Function to ensure successful control of PCP-controlled devices by UPnP Control Points. Two configurations are considered: o No NAT function is embedded in the CP router. This function is required for instance in DS-Lite or NAT64 deployments; o The CP router embeds a NAT function. Boucadair, et al. Expires April 11, 2011 [Page 3] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 2. Acronyms This document make use of the following abbreviations: o CP router: Customer Premise router o DS-Lite: Dual-Stack Lite o IGD: Internet Gateway Device o IE: Informational Element o IWF: Interworking Function o NAT: Network Address Translation o PCP: Port Control Protocol o UPnP: Universal Plug and Play 3. Architecture Model As a reminder, Figure 2 illustrates the architecture model adopted by UPnP IGD. In Figure 2, the following UPnP terminology is used: o Client refers to a host located in the local network. o IGD Control Point is a UPnP control point using UPnP to control an IGD (Internet Gateway Device). o Host represents a remote host reachable in the Internet. Boucadair, et al. Expires April 11, 2011 [Page 4] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 +-------------+ | IGD Control | | Point |-----+ +-------------+ | +-----+ +------+ +---| | | | | IGD |-------| Host | +---| | | | +-------------+ | +-----+ +------+ | Client |-----+ +-------------+ Figure 2: UPnP IGD Model This model is not valid when PCP is used to control a Provider NAT while internal hosts continue to use UPnP. In such scenarios, Figure 3 shows the updated model. +-------------+ | IGD Control | | Point |-----+ +-------------+ | +-----+ +--------+ +------+ +---| IGD-| |Provider| |Remote| | PCP |-------| NAT |-----| Host | +---| IWF | | | | | +-------------+ | +-----+ +--------+ +------+ | Local Host |-----+ +-------------+ LAN Side External Side <======UPnP IGD==========><======PCP=====> IWF: Interworking Function Figure 3: UPnP IGD-PCP Interworking Model In the updated model depicted in Figure 3, one or two levels of NAT can be encountered in the data path. Indeed, in addition to the Provider NAT, the CP router may embed a NAT function (Figure 4). Boucadair, et al. Expires April 11, 2011 [Page 5] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 +-------------+ | IGD Control | | Point |-----+ +-------------+ | +-----+ +----+ +------+ +---| IGD-| | | |Remote| | PCP |-------|NAT2|-----| Host | +---| IWF | | | | | +-------------+ | +-----+ +----+ +------+ | Local Host |-----+ NAT1 +-------------+ Figure 4: Cascaded NAT scenario To ensure a successful interworking between UPnP IGD and PCP, an interworking function is embedded in the CP router. In the model defined in Figure 3, all UPnP IGD server-oriented functions, a PCP Client [I-D.wing-softwire-port-control-protocol] and a UPnP IGD-PCP Interworking Function are embedded in the CP router (i.e., IGD). In the rest of the document, IGD-PCP Interworking Function refers to PCP Client and UPnP IGD-PCP Interworking Function. UPnP IGD-PCP Interworking Function is responsible for generating a well-formed PCP (resp., UPnP IGD) message from a received UPnP IGD (resp., PCP) message. 4. UPnP IGD-PCP Interworking Function: Overview Table 1 provides the mapping between WANIPConnection parameters and PCP parameters while Table 2 focuses on the correspondence between supported methods. Note that some enhancements have been integrated in WANIPConnection as documented in [IGD2]. In the following table, IE stands for Informational Element. PCP IEs are defined in the base PCP document. Boucadair, et al. Expires April 11, 2011 [Page 6] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 +----------------------------+-----------+--------------------------+ | WANIPConnection | PCP | Comments | +----------------------------+-----------+--------------------------+ | PortMappingEnabled | NA | When set to 1, this | | | | parameter MUST NOT be | | | | reproduced as an | | | | argument in PCP | | | | messages. If set to 0, | | | | this is the default PCP | | | | mode (no explicit | | | | indication in PCP | | | | messages). PCP does not | | | | support deactivating the | | | | dynamic NAT mapping | | | | since the initial goal | | | | of PCP is to ease the | | | | traversal of Provider | | | | NAT. Supporting such | | | | per-subscriber function | | | | may overload the | | | | Provider NAT. | | --- | | | | PortMappingLeaseDuration | Requested | PCP recommends 3600s as | | | Mapping | default value. When | | | Lifetime | PortMappingLeaseDuration | | | | is set to 0, a maximum | | | | lifetime value MAY be | | | | included in the | | | | corresponding PCP | | | | message. PCP allows for | | | | a maximum value of 65536 | | | | seconds while UPnP IGD | | | | allows 604800 seconds | | | | (i.e., one week) as a | | | | maximum bound. | | --- | | | | ExternalPort | Hinted | PCP does not support | | | External | explicit wildcard | | | Port | values. If ExternalPort | | | Number | is a wildcard value, no | | | | Hinted External Port | | | | Number MUST be enclosed | | | | in the corresponding PCP | | | | message. | | --- | | | | InternalPort | Internal | None. | | | Port | | | | Number | | Boucadair, et al. Expires April 11, 2011 [Page 7] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 | --- | | | | PortMappingProtocol | Transport | IGD only supports TCP | | | Protocol | and UDP. | | --- | | | | InternalClient | Internal | InternalClient can be an | | | IP | IP address or a FQDN. | | | Address | Only an IP address | | | | scheme is supported in | | | | PCP. | | -- | | | | ExternalIPAddress | External | | | | IP | | | | Address | | | --- | | | | PortMappingDescription | NA | Not supported in PCP. | | | | When present in UPnP IGD | | | | messages, this parameter | | | | MUST NOT be propagated | | | | in the corresponding PCP | | | | messages. [[NOTE: can | | | | be added as an optional | | | | PCP IE]] | | --- | | | | RemoteHost | | PCP RECOMMENDS to | | | | configure the CP | | | | router's firewall | | | | instead of overloading | | | | the Provider NAT. | | --- | | | | PossibleConnectionTypes | NA | Out of scope of PCP | | -- | | | | ConnectionStatus | NA | Out of scope of PCP | | -- | | | | PortMappingNumberOfEntries | NA | Managed locally by the | | | | UPnP IGD-PCP | | | | Interworking Function | | -- | | | | SystemUpdateID | NA | Managed locally by the | | | | UPnP IGD-PCP | | | | Interworking Function | +----------------------------+-----------+--------------------------+ Table 1: UPnP IGD-PCP: Variables Boucadair, et al. Expires April 11, 2011 [Page 8] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 +-----------------------------+-------------+-----------------------+ | WANIPConnection | PCP | Comments | +-----------------------------+-------------+-----------------------+ | GetGenericPortMappingEntry | PCP does | IGD-PCP Interworking | | | not support | Function maintains an | | | yet a | updated list of | | | method for | active mappings | | | listing | instantiated in the | | | active | PCP Server by | | | mappings | internal hosts (See | | | | Section 5.8 and | | | | Section 5.10 for more | | | | information). | | --- | | | | GetSpecificPortMappingEntry | PCP does | Under normal | | | not support | conditions, the | | | yet a | IGD-PCP Interworking | | | method for | Function maintains an | | | listing | updated list of | | | active | active mapping as | | | mappings | instantiated in the | | | | PCP Server. The | | | | IGD-PCP Interworking | | | | Function locally | | | | handles this request | | | | and provides back the | | | | port mapping entry | | | | based on the | | | | ExternalPort, the | | | | PortMappingProtocol, | | | | and the RemoteHost. | | --- | | | | AddPortMapping | PINxy | We recommend the use | | | | of | | | | AddAnyPortMapping() | | | | instead of | | | | AddPortMapping(). | | | | Refer to | | | | Section 5.7.2 for | | | | more details if | | | | AddPorMapping() is | | | | used. | | --- | | | | DeletePortMapping | PINxy with | None. | | | a lifetime | | | | positioned | | | | to 0 | | | --- | | | Boucadair, et al. Expires April 11, 2011 [Page 9] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 | GetExternalIPAddress | [Open | | | | discussion: | | | | PCP does | | | | not support | | | | yet a | | | | method for | | | | retrieving | | | | the | | | | external IP | | | | address] | | | --- | | | | DeletePortMappingRange() | PINxy with | A range of port | | | a lifetime | numbers can be | | | positioned | included in a PCP | | | to 0 | request to delete | | | | mappings | | --- | | | | GetListOfPortMappings() | PCP does | | | | not support | | | | yet a | | | | method for | | | | listing | | | | active | | | | mappings | | | --- | | | | AddAnyPortMapping() | PINxy | No issue is | | | | encountered to proxy | | | | this request to the | | | | PCP Server. | +-----------------------------+-------------+-----------------------+ Table 2: IGD-PCP: Methods [NOTE: Add IGD-PCP error table] 5. Specification of the IGD-PCP Interworking Function This section covers the scenarios with or without NAT in the CP router. 5.1. PCP Server Discovery The IGD-PCP Interworking Function implements one of the discovery methods identified in [I-D.wing-softwire-port-control-protocol] (e.g., DHCP [I-D.bpw-softwire-pcp-dhcp]). The IGD-PCP Interworking Function behaves as a PCP Client when communicating with the provisioned PCP Server. Boucadair, et al. Expires April 11, 2011 [Page 10] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 When the IGD-PCP Interworking Function encounters reachability problems (e.g., failure to retrieve an IP address of the PCP Server, routing issue, etc.) to reach a PCP Server, and if an IP address has been successfully assigned to the external interface of the device embedding the IGD-PCP Interworking Function, IGD-PCP Interworking Function MUST NOT be invoked. Indeed, UPnP machinery is used to control that device. Once the PCP Sever is reachable, the IGD-PCP Interworking Function MUST synchronise its states as specified in Section 5.10. 5.2. Control of the Firewall In order to configure security policies to be applied to inbound and outbound traffic, UPnP IGD can be used to control a local firewall engine. No IGD-PCP Interworking Function is therefore required for that purpose. 5.3. NAT Control in LAN Side Internal UPnP Control Points are not aware of the presence of the IGD-PCP Interworking Function in the CP router (IGD). Especially, UPnP Control Points MUST NOT be aware of the deactivation of the NAT in the CP router. No modification is required in the UPnP Control Point. 5.4. Port Mapping Tables IGD-PCP Interworking Function MUST store locally all the mappings instantiated by internal UPnP Control Points in the PCP Server. Port Forwarding mappings SHOULD be stored in a permanent storage. If not, upon reset or reboot, the IGD-PCP Interworking Function MUST synchronise its states as specified in Section 5.10. Upon receipt of a PCP PINxy Response from the PCP Server, the IGD-PCP Interworking Function MUST retrieve the enclosed mapping(s) and MUST store it in the local mapping table. The local mapping table is an image of the mapping table as maintained by the PCP Server for a given subscriber. 5.5. Interworking Function Without NAT in the CP Router When no NAT is embedded in the CP router, the content of received WANIPConnection and PCP messages is not altered by the IGD-PCP Interworking Function (i.e., the content of WANIPConnection messages Boucadair, et al. Expires April 11, 2011 [Page 11] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 are copied to the PCP messages (and vice versa) according to Table 1). 5.6. NAT Embedded in the CP Router Unlike the scenario with one level of NAT (Section 5.5), the IGD-PCP Interworking Function MUST update their content of received mapping messages with the IP address and/or port number belonging to the external interface of the CP router (i.e., after the NAT1 operation in Figure 4) and not as initially positioned by the UPnP Control Point. All WANIPConnection messages issued by the UPnP Control Point (resp., PCP Server) are intercepted by the IGD-PCP Interworking Function. Then, the corresponding messages (see Table 1 and Table 2) are generated by the IGD-PCP Interworking Function and sent to the provisioned PCP Server (resp., corresponding UPnP Control Point). The content of PCP messages received by the PCP Server reflects the mapping information as enforced in the first NAT. In particular, the internal IP address and/or port number of the requests are replaced with the IP address and port number as assigned by the NAT of the CP router. For the reverse path, PCP response messages are intercepted by the IGD-PCP Interworking Function. The content of the corresponding WANIPConnection messages are updated: o The internal IP address and/or port number as initially positioned by the UPnP Control Point and stored in the CP router NAT are used to update the corresponding fields in received PCP responses. o The external IP and port number are not altered by the IGD-PCP Interworking Function. o The NAT mapping entry in the first NAT is updated with the result of PCP request. The lifetime of the mappings instantiated in all involved NATs SHOULD be the one assigned by the terminating PCP Server. In any case, the lifetime MUST be lower or equal to the one assigned by the terminating PCP Server. [[ NOTE: Do we need to indicate somehow that some flows are not meant to exit a local domain and then there is no need to instantiate a mapping in the upstream NAT? A flow has local (private) significance, Internet-only significance or both. Boucadair, et al. Expires April 11, 2011 [Page 12] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 * In the case of private-only significance, UPnP provides a mapping on its own. * In the case of Internet-only, without a PCP server, the UPnP side can deny the request * In the case of both, without a PCP server, UPnP still provides a mapping. Synch procedure is needed after PCP Server is reachable. The open question is that we lack a mechanism to determine the significance (possibly out of scope). If there is a mechanism the rules above can be followed. Without a mechanism if PCP Client is enabled but PCP Server in unreachable, UPnP should always return a mapping and synch later. ]] 5.7. Creating a Mapping Two methods can be used to create a mapping: AddPortMapping() or AddAnyPortMapping(). AddAnyPortMapping() is the RECOMMENDED method. 5.7.1. AddAnyPortMapping() When an UPnP Control Point issues a AddAnyPortMapping(), this request is received by the UPnP Server. This request is then relayed to the IGD-PCP Interworking Function which generates a PCP PINxy Request (see Table 1 for mapping between WANIPConnection and PCP parameters). Upon receipt of PCP PINxy Response from the PCP Server, an XML mapping is returned to the requesting UPnP Control Point (the content of the messages follows the recommendations listed in Section 5.6 or Section 5.5 according to the deployed scenario). If a PCP Error is received from the PCP Server, a corresponding WANIPConnection error code is generated by the IGD-PCP Interworking Function and sent to the requesting UPnP Control Point. 5.7.2. AddPortMapping() At least three approaches that have been discussed in design meetings, which can be separated into two categories: the server must grant the requested external port (or return an error), or the server can map to any external port. 5.7.2.1. Alternative 1: Preferred Port Number and No Use of M-bit Upon receipt of AddPortMapping() from an UPnP Control Point, the IGD- PCP Interworking Function first checks if the requested external port number is not used by another Internal UPnP Control Point. In case a mapping bound to the requested external port number is found in the Boucadair, et al. Expires April 11, 2011 [Page 13] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 local table, the IGD-PCP Interworking Function MUST send back an error to the requesting UPnP Control Point. This exchange is re-iterated until an external port number that is not in use is requested by the UPnP Control Point. Then, the IGD-PCP Interworking Function generates a PCP PINxy Request with all requested mapping information as indicated by the UPnP Control Point if no NAT is embedded in the CP router or updated as specified in Section 5.6. A shortened requested lifetime SHOULD be used by the IGD-PCP Interworking Function when generating the corresponding request to the PCP Server (this is motivated by port usage optimisation needs). Once received by the PCP Server, a PCP PINxy Response or a PCP Error MUST be issued. In case a positive answer from the PCP Server is received by the IGD-PCP Interworking Function, the returned mapping MAY be different from the one requested by the UPnP Control Point. The returned mapping MUST be stored by the IGD-PCP Interworking Function in its local mapping table. o If the returned mapping matches the mapping requested by the UPnP Control Point, a positive answer MUST be sent to the requesting UPnP Control Point. This answer terminates this exchange; o If not, the IGD-PCP Interworking Function uses the stored mapping as the only valid candidate to reply to any subsequent-related request from the same UPnP Control Point pointing to the same internal Client. Especially, no PCP message related to this mapping request MUST be relayed to the PCP Server until that mapping expires. * If the UPnP Control Point succeeds to retrieve the mapping from the IGD-PCP Interworking Function, the UPnP Control Point SHOULD refresh the mapping if the mapping is still in use. * The IGD-PCP Interworking Function SHOULD delete the mapping in the PCP Server if the UPnP Control Point abandoned to create a mapping for the same internal port number and IP address (a timer can be defined for this purpose). If no explicit delete request is sent by the IGD-PCP Interworking Function, the corresponding mapping MUST be dropped by the PCP Server upon expiration of the lifetime. Figure 5 shows an example of the flow that occurs when the PCP Server satisfies the requests. Figure 6 shown the messages exchanges when the requested port is in use. Boucadair, et al. Expires April 11, 2011 [Page 14] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 UPnP-PCP UPnP Control Interworking Point Function PCP Server | | | | (1) AddPortMapping | | |--------------------->| | | |(2) PCP Map Create Request | | |-------------------------->| | | | | |(3) PCP Map Create Response| | |<--------------------------| | (4) AddPortMapping | | |<---------------------| | Figure 5: Flow Example (Positive Answer) Boucadair, et al. Expires April 11, 2011 [Page 15] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 UPnP-PCP UPnP Control Interworking Point Function PCP Server | | | | (1) AddPortMapping | | |--------------------->| | | |(2) PCP Map Create Request | | |-------------------------->| | | | | |(3) PCP Map Create Response| | |<--------------------------| | (4) Error: | | |ConflictInMappingEntry| | |<---------------------| | | (5) AddPortMapping | | |--------------------->| | | (6) Error: | | |ConflictInMappingEntry| | |<---------------------| | .... |<---------------------| | | (a) AddPortMapping | | |--------------------->| | | (b) Error: | | |ConflictInMappingEntry| | |<---------------------| | Figure 6: Flow Example (Negative Answer) 5.7.2.1.1. Analysis The main advantage of this alternative is it avoids overloading the PCP Server with remaining exchanges. Subsequent UPnP exchanges will remain in the local area and won't be relayed to the PCP Server. 5.7.2.2. Alternative 2 A bit, called the Mandatory Bit in draft-wing-softwire-port-control-protocol was proposed to toggle the behavior in a Request message. A variant would be to define an IE for this purpose instead of having a fixed bit. Figure 5 shows an example of the flow that occurs when the PCP Server satisfies the requests. Figure 7 shown the messages exchanges when Boucadair, et al. Expires April 11, 2011 [Page 16] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 the requested port is in use. UPnP-PCP UPnP Control Interworking Point Function PCP Server | | | | (1) AddPortMapping | | |--------------------->| | | |(2) PCP Map Create Request | | |-------------------------->| | | | | |(3) PCP Map Create Response| | |<--------------------------| | (4) Error: | | |ConflictInMappingEntry| | |<---------------------| | | (5) AddPortMapping | | |--------------------->| | | |(6) PCP Map Create Request | | |-------------------------->| | | | | |(7) PCP Map Create Response| | |<--------------------------| | (8) Error: | | |ConflictInMappingEntry| | |<---------------------| | .... | (a) AddPortMapping | | |--------------------->| | | |(b) PCP Map Create Request | | |-------------------------->| | | | | |(c) PCP Map Create Response| | |<--------------------------| | (d) Error: | | |ConflictInMappingEntry| | |<---------------------| | Figure 7: Flow Example 5.7.2.2.1. Analysis The main disadvantage of this alternative is it overloads the PCP Server with remaining exchanges as shown in Figure 7. Boucadair, et al. Expires April 11, 2011 [Page 17] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 5.7.2.3. Alternative 3 In this alternative the PCP Client indicates a preferred mandatory port number. 0 is used to indicate no port value is preferred. When the PCP Client receives a PCP Error from the PCP Server, it does not include a preferred port number in the subsequent requests. Figure 5 shows an example of the flow exchange that occurs when the PCP Server satisfies the request. Figure 8 shows the messages exchange when the requested port is in use. Boucadair, et al. Expires April 11, 2011 [Page 18] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 UPnP-PCP UPnP Control Interworking Point Function PCP Server | | | | (1) AddPortMapping | | |--------------------->| | | |(2) PCP Map Create Request | | |-------------------------->| | | | | |(3) PCP Map Create Response| | |<--------------------------| | (4) Error: | | |ConflictInMappingEntry| | |<---------------------| | | (5) AddPortMapping | | |--------------------->| | | |(6) PCP Map Create Request | | |-------------------------->| | | | | |(7) PCP Map Create Response| | |<--------------------------| | (8) Error: | | |ConflictInMappingEntry| | |<---------------------| | | (5) AddPortMapping | | |--------------------->| | | (6) Error: | | |ConflictInMappingEntry| | |<---------------------| | .... |<---------------------| | | (a) AddPortMapping | | |--------------------->| | | (b) Error: | | |ConflictInMappingEntry| | |<---------------------| | Figure 8: Flow Example (Negative Answer) 5.8. Listing One or a Set of Mappings In order to list active mappings, an UPnP Control Point may issue GetGenericPortMappingEntry(), GetSpecificPortMappingEntry() or GetListOfPortMappings(). These methods MUST NOT be proxied to the PCP Server since a local Boucadair, et al. Expires April 11, 2011 [Page 19] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 mapping is maintained by the IGD-PCP Interworking Function. 5.9. Delete One or a Set of Mappings An UPnP Control Point proceeds to the deletion of one or a list of mappings by issuing DeletePortMapping() or DeletePortMappingRange(). When one of these messages is received by the IGD-PCP Interworking Function, it first checks if the requested mapping to be removed is present in the local mapping table. o If no mapping matching the request is found in the local table, an error is sent back to the UPnP Control Point; o Otherwise, PCP PINxy delete request is generated taking into account the input arguments * as included in DeletePortMapping() or DeletePortMappingRange() if no NAT is enabled in the CP router; * or the corresponding local IP address and port number as assigned by the local NAT if a NAT is enabled in the CP router. o Once received by the PCP Server, it proceeds to removing the corresponding entry(ies), a PCP PINxy Delete Response is sent back if the removal of the corresponding entry(ies) was successful; if not, a PCP Error is sent back to the IGD-PCP Interworking Function including the corresponding error cause (e.g., not authorised). When a positive answer is received from the PCP Server, the IGD-PCP Interworking Function updates its local mapping table (i.e., remove the corresponding entry(ies)) and notifies the UPnP Control Point about the result of the removal operation. 5.10. Mapping Synchronisation [[Note: This section needs further discussion among authors]] Under normal conditions, since a valid copy of the mapping table is stored locally in the CP router, the IGD-PCP Interworking Function SHOULD NOT issue any subsequent PCP request to handle a request received from an UPnP Control Point to list active mappings. Nevertheless, in case of loss of synchronisation (e.g., reboot, system crashes, power outage, etc.), the IGD-PCP Interworking Function SHOULD generate a PCP Map List Request to retrieve all active mappings in the PCP Server and update its local mapping table without waiting for an explicit request from a UPnP Control Point. Doing so, the IGD-PCP Interworking Function maintains an updated mapping table. Boucadair, et al. Expires April 11, 2011 [Page 20] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 In case of massive reboot of CP routers (e.g., avalanche restart phenomenon), PCP request bursts SHOULD be avoided. For this aim, we recommend the use of a given timer denoted as PCP_SERVICE_WAIT. This timer can be pre-configured in the CP router or to be provisioned using a dedicated means such as DHCP (See Section 3.3 of [I-D.bpw-softwire-pcp-dhcp]). Upon reboot of the CP router, PCP messages SHOULD NOT be sent immediately. A random value is selected between 0 and PCP_SERVICE_WAIT. This value is referred to as RAND(PCP_SERVICE_WAIT). Upon the expiration of RAND(PCP_SERVICE_WAIT), the CP router SHOULD proceed to its synchronisation operations (i.e., retrieve all active mappings which have been instructed by internal UPnP Control Point(s)). 6. IANA Considerations This document makes no request of IANA. Note to RFC Editor: this section may be removed on publication as an RFC. 7. Security Considerations This document does not introduce any new security consideration compared to what is elaborated in [I-D.wing-softwire-port-control-protocol] and [Sec_DCP]. 8. Acknowledgements Authors would like to thank F. Fontaine and C. Jacquenet for their review and comments. 9. References 9.1. Normative References [I-D.wing-softwire-port-control-protocol] Wing, D., Penno, R., and M. Boucadair, "Pinhole Control Protocol (PCP)", draft-wing-softwire-port-control-protocol-02 (work in progress), July 2010. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Boucadair, et al. Expires April 11, 2011 [Page 21] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 9.2. Informative References [I-D.bpw-softwire-pcp-dhcp] Boucadair, M., Penno, R., and D. Wing, "DHCP and DHCPv6 Options for Port Control Protocol (PCP)", draft-bpw-softwire-pcp-dhcp-01 (work in progress), May 2010. [I-D.ietf-behave-v6v4-xlate-stateful] Bagnulo, M., Matthews, P., and I. Beijnum, "Stateful NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers", draft-ietf-behave-v6v4-xlate-stateful-12 (work in progress), July 2010. [I-D.ietf-softwire-dual-stack-lite] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- Stack Lite Broadband Deployments Following IPv4 Exhaustion", draft-ietf-softwire-dual-stack-lite-06 (work in progress), August 2010. [IGD2] UPnP Forum, "UPnP IGD1 vs. IGD2 (http://www.upnp.org/ resources/documents/UPnPIGDv2vsIGDv1_20100412.pdf)", March 2010. [Sec_DCP] UPnP Forum, "Device Protection:1", November 2009. Authors' Addresses Mohamed Boucadair France Telecom Rennes, 35000 France Email: mohamed.boucadair@orange-ftgroup.com Reinaldo Penno Juniper Networks 1194 N Mathilda Avenue Sunnyvale, California 94089 USA Email: rpenno@juniper.net Boucadair, et al. Expires April 11, 2011 [Page 22] Internet-Draft UPnP IGD-PCP Interworking Function October 2010 Dan Wing Cisco Systems, Inc. 170 West Tasman Drive San Jose, California 95134 USA Email: dwing@cisco.com Boucadair, et al. Expires April 11, 2011 [Page 23]