INTERNET DRAFT Georg Kullgren GSMP Working Group Stephen Shew Nortel Networks Hormuzd Khosravi Intel Jonathan Sadler Tellabs Satoru Okamoto Kohei Shiomoto Atsushi Watanabe NTT Expires August 2002 Requirements for adding optical support to GSMPv3 Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 10 of RFC2026 except that the right to produce derivative works is not granted. 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/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Abstract This memo provides an overview of additional requirements on the GSMP protocol. Kullgren, et. al. Expires August 2002 [Page 1] Internet Draft GSMP updates February 2002 Table of Contents 1. Overview .......................................................... 3 2. Requirements for Optical Support .................................. 3 2.1. Label Types .................................................... 3 2.2. Port and Label Management Issues ............................... 4 2.3. Statistics messages ............................................ 4 2.4. Configuration Issues ........................................... 4 2.4.1. Switch Configuration ........................................ 4 2.4.2. Port Configuration .......................................... 4 2.4.3. Service Configuration ....................................... 5 2.5. Service Model Issues ........................................... 5 2.6. Encapsulation issues ........................................... 5 2.7. MIB Issues ..................................................... 6 2.8. OXC Transaction Model .......................................... 6 2.8.1 Serial Transactions .......................................... 6 2.8.2. Bulk Transactions ........................................... 6 2.9. OXC Restoration Capabilities ................................... 6 2.9.1. Non-Reserved Protection Links ............................... 7 2.9.2. Dedicated Protection Links .................................. 7 2.9.3. Protection Triggers ......................................... 8 2.9.4. Protection Link Capabilities ................................ 8 2.10 GSMP support to optical cross-connect system ................... 9 3. Requirements from Implementors ................................... 10 3.1. GSMP Packet Format ............................................ 10 3.1.1. Message segmentation ....................................... 10 3.1.1.1. "More" Result Flag ...................................... 10 3.1.1.2. SubMessage Number ....................................... 10 3.1.1.3. I flag .................................................. 10 3.1.1.4. Updated Messages ........................................ 10 3.1.1.5. Message Segmentation example ............................ 11 3.1.2. Transaction Identifier ..................................... 11 3.2. Window Size ................................................... 11 3.3. Retransmission ................................................ 11 3.4. Delete Branches Message ....................................... 12 3.5. Adjacency ..................................................... 12 3.5.1. Loss of Synchronisation .................................... 12 3.6. ReturnReceipt Result value in Events .......................... 12 4. Additional Requirements .......................................... 13 5. Security Considerations .......................................... 14 6. Acknowledgements ................................................. 14 7. References ....................................................... 15 8. Author's Addresses ............................................... 17 9. Full Copyright Statement ......................................... 18 Kullgren, et. al. Expires August 2002 [Page 2] Internet Draft GSMP updates February 2002 1. Overview This draft is intended to describe the required updates to GSMP requested by implementors and the required changes for support of optical (non-transparent and all optical), SONET/SDH, and spatial switching of IP packets, L2 frames and TDM data. The mix of possible instantiations include GSMP controllers connected to: photonic cross- connects (optical-optical), transparent optical cross connects (optical-electrical-optical, frame independent), opaque cross connects (optical-electrical-optical, SONET/SDH frames), and traditional TDM switches (all electrical). These could form IP based optical routers, optical label switches, wavelength routers, and dynamic optical cross connects. There are also several different generic models that might be applied to running IP over WDM [1][2][11]. This document defines the requirements for the separation of control functions from data functions in order to provide a more flexible network architecture.[3] In this draft, no position will be taken about the eventual architectural model that will be most appropriate (e.g., single or multiple routing plane instances). The only assumption is that the ability to separate the control mechanisms from the data switching is as useful for the signaling of optical paths (e.g., GMPLS) as it is for the signaling of L2 paths (e.g., MPLS). GSMPv3[6] is well suited for providing the control mechanisms necessary for allowing an IP based controller to direct the activities of an optical switch. In order for GSMP to operate between IP controllers and optical switches and cross connects, support for optical labels and service and resource abstractions must be added to GSMP. 2. Requirements for Optical Support 2.1. Label Types New labels are needed to identify the entities that are to be switched in the optical fabric. These are longer than GSMPv3 labels as they have physical and structural context. As GMPLS[1][2] has had very similar requirements for label formats alignment with GMPLS is proposed. This includes support for: - Digital Carrier Hierarchy (e.g., DS-1, E1) - SONET and SDH Hierarchy (e.g., OC-3, STM-1, VT1.5, VC-12) - PDH labels [12] - OTN G.709 labels Kullgren, et. al. Expires August 2002 [Page 3] Internet Draft GSMP updates February 2002 - Lambdas - Fibers GSMP MUST include support for all label types as well as for label hierarchies and label lists as defined by GMPLS. Bundles of the above labels SHOULD also be supported (e.g., 5 OC- 3s, contiguous wavebands) 2.2. Port and Label Management Issues As with routers, it may be useful to recognize bundles of links [13] between optical cross-connects. This goes beyond knowledge of separate independent ports. If so, changes to the port management message MAY be needed to describe ports which are part of a link bundle. An updated label range message MUST be provided. There MUST also be support of multiplexing (e.g. no multiplexing, SONET, Gigabit Ethernet multiplexing etc). 2.3. Statistics messages No changes are currently proposed for the statistics messages to support optical switching. 2.4. Configuration Issues 2.4.1. Switch Configuration No changes are currently proposed for the switch configuration messages to support optical switching. 2.4.2. Port Configuration The port configuration message supplies the controller with the configuration information related to a single port. In order to handle the specific port types in an optical switch, extensive additions will need to be made to this command. Port types MUST be added to support the mix of SONET/SDH signals that can operate over a single fiber. Information that MAY need to be conveyed includes[8]: - wavelengths available per interface Kullgren, et. al. Expires August 2002 [Page 4] Internet Draft GSMP updates February 2002 - bit rate per wavelength - type of fiber Again, it MAY be useful to recognize bundles of links [13] between optical cross-connects. If so, changes to the port configuration message would be needed to describe ports which are part of a link bundle. 2.4.3. Service Configuration While new capability sets MUST be added to support quality parameters in optical switches, no changes are foreseen to the service configuration message as its role to carry the service information as defined in the applicable service model. The changes related to the service model will be discussed in section 0. 2.5. Service Model Issues While one assumption of using optical media is that bandwidth is plentiful, it should be expected that traffic engineering will be necessary in any case[3]. GSMP provides the means for each connection, or in this each light trail, to be created with specific quality attributes. Capability to control re-timing and re-shaping MUST be added. Currently, the default set of service models in GSMP are all based on the services models defined elsewhere, e.g. the Intserv model[5][7], the Diffserv[4] model, ATM QoS models and the Frame relay forum QoS models. A determination needs to be made of the applicable quality models for optical channel trails. These models MUST then be mapped to the GSMP capability set mechanism. 2.6. Encapsulation issues The working group needs to decide whether a new encapsulation is required. In other words, will all optical switches used in either the MPLS over Optics and the IP over optics applications require that IP be implemented on the control channel connecting the GSMP controller and Optical switch (the GSMP target). If a raw wavelength control connection is to be allowed, a new encapsulation SHOULD be defined. Kullgren, et. al. Expires August 2002 [Page 5] Internet Draft GSMP updates February 2002 2.7. MIB Issues If a new encapsulation is defined, then the encapsulation group SHOULD be updated. No other changes should be required. 2.8. OXC Transaction Model 2.8.1 Serial Transactions Many existing OXCs use a command interface which assumes a serial transaction model. That is, a new command cannot be issued or processed until the existing command is completed. Under provisioning control via a network management application, and with non-dynamic path setup, this model has been adequate. Moving to a dynamic path setup capability with a distributed control plane, a parallel transaction model is likely required for performance. This is particularly helpful when the performance of setting up a TDM style connection is much slower than setting up an L2 connection table. If the OXC is not able to support a parallel transaction model, a GSMP controller MUST be informed of this and adopt serial transaction behaviour. 2.8.2. Bulk Transactions Again due to the time it may take some OXCs to setup TDM connections relative to L2 fabrics (e.g., VC-4/STS-1 SPE fabric in an HOVC/STS switch), support for sending multiple transactions in the same message is a useful optimization. When an OXC receives a bulk message, the individual transactions are acted upon and a single reply is sent. If parallel transactions are not supported, bulk messages can improve performance by reducing transaction overhead. Bulk transactions SHOULD be supported. 2.9. OXC Restoration Capabilities To achieve fast link protection performance (e.g., 50 ms after failure detection), SONET/SDH and some OXC systems use hardware based protection schemes (e.g., ring protection). Achieving this level of performance solely using a data control plane such as GMPLS is a serious challenge. An alternate approach is to utilize fast restoration capabilities of an OXC with a dynamic control plane. An implication of this hybrid approach is that extensions are needed to GSMP to provision the behaviour of an OXC in anticipation of a link failure. Kullgren, et. al. Expires August 2002 [Page 6] Internet Draft GSMP updates February 2002 This differs from the strict master-slave relationship in GSMP for Layer 2 switches in that here the OXC is capable of taking an action independent of the GSMP controller and then informing the controller afterwards. 2.9.1. Non-Reserved Protection Links An example of protection OXC behaviour is that when a link fails, a backup link may be used to protect traffic on. This backup link could be selected from a set of links, none of which are pre- reserved. A backup link could be shared with one or more "working" links which is a form of 1:n shared protection. Specifying the set of possible backup links SHOULD be done as an option to the Add- Branch message. When a backup link is used or the OXC reverts back to the original link, the control plane (i.e., signalling) may need to know about the new path state in order to notify the operator, or take some other OAM action (e.g., billing, SLA monitoring). An additional GSMP message to inform the controller SHOULD be added to do this. 2.9.2. Dedicated Protection Links A more specialized form of restoration called "1+1" defines a (usually node disjoint) protection path in a transport/optical network for a given working path. At the ingress node to the path, the traffic signal is sent simultaneously along both working and protection paths. Under non-failure conditions at the egress node, only the last link of the working path is connected to the client. When any link in the working path fails, traffic on the working path ceases to be received at end of the path. The egress OXC detects this condition and then switches to use the last link of the protection path without the controller having to issue a Move-Input- Branch message. At no time is the ingress node aware which link the egress node is using. Selection of the protection path and all of its links is outside the scope of GSMP. Specification of the two output branches at the ingress node can be done with the usual Add-Branch semantics. The ingress node protection link is not shared with any other working link. Specification of the two input branches at the egress node should be done when the Add-Branch message is sent. This SHOULD be an option to that message. The egress node protection link is not shared with any other working link. Kullgren, et. al. Expires August 2002 [Page 7] Internet Draft GSMP updates February 2002 When a protection link is used or the OXC reverts back to the working link, the control plane (i.e., signalling) may need to know about the new path state in order to notify the operator, or take some other OAM action (e.g., billing, SLA monitoring). An additional GSMP message to inform the controller SHOULD be added to do this. If an alternate input port is not specified with an original Add- Branch message, it MAY be specified in a subsequent Add-Branch message. In this case, it is useful to include information about existing users of the output port in that Add-Branch message. This helps the OXC immediately learn of the association between the new input port and an existing one. The association is used to enable OXC protection procedures. This capability MUST be added to the add- branch message. Similar contextual information is needed for a Delete-Branch message so that the OXC can determine if a path becomes unprotected. This capability MUST be added to the Delete-branch message. 2.9.3. Protection Triggers Aside from link or equipment failures, there are a variety of maintenance conditions that could cause the backup/protection link(s) to be used. These may include: - Scheduled maintenance of the working link. Here the network operator deliberately takes a link out of service to perform maintenance. - Reconfiguration of fiber/node/network which causes temporary need to use backup links. It may be useful to specify these triggers when the backup/protection links are defined with the Add-Branch message. This depends on how the OXC is implemented to be aware of such triggers. This is for further study. 2.9.4. Protection Link Capabilities When an OXC has the capability to perform protection switching independently from the OCC, it may be useful for the OCC to be informed of these capabilities at switch and/or port configuration. Applications in the GSMP controller could use this information. For example, signalling clients could define a path protection scheme over multiple GSMP enabled OXCs. This is for further study. Kullgren, et. al. Expires August 2002 [Page 8] Internet Draft GSMP updates February 2002 2.10 GSMP support to optical cross-connect system The cross-connect system such as photonic cross-connect, transparent optical cross-connect, opaque cross-connect and traditional TDM switch can be consist of not only cross-connect (/switch) function, but also multiplexing function (including transmission function), path termination function (including client signal termination function). In the optical cross-connect (OXC) system, the multiplexing function corresponds to the wavelength division multiplexing (WDM). The optical regenerator and wavelength converter may be necessary in order to realize long-haul transmission and to use effectively the wavelength resource respectively. Figure 1 shows the generalized OXC functional block. The OXC system shown in Fig.1 should be controlled / managed by GSMP. The advantage of this concept is that the GSMP can control the OXC system, without other control protocols. This will reduce the cost and time of OXC control application development. To control the OXC system, the control concept of both connection termination and trail termination for each optical label switched path or WDM sections (defined in G.872; OMS and OTS) should be introduced in the GSMP. The GSMP for optical switch can be located as subset of that for optical cross-connect. +-------------+-------------------+-----------+ -->| | | | WDM | Wavelength | Opt. regenerator/ | Opt. | signals | demultiplex/| Wavelength | switch | | multiplex | converter | | <--| | | | +-------------+-------------------+-----------+ || || Client +-----------+ signals (In) -->| Path | Client | terminator| signalis(Out) <--| | +-----------+ Figure 1 General OXC functional block Kullgren, et. al. Expires August 2002 [Page 9] Internet Draft GSMP updates February 2002 3. Requirements from Implementors 3.1. GSMP Packet Format The Basic GSMP Message Format in chapter 3.1.1 in [6] describes the common fields present in all GSMP messages except for the Adjacency protocol. 3.1.1. Message segmentation If a message exceeds the MTU of the link layer it has to be segmented. This was originally done with the "More" flag in the Result field. The addition of the I flag and the SubMessage Number to the header has made the "More" flag in the Result field obsolete. A clarification of the I flag and SubMessage Number is also needed. 3.1.1.1. "More" Result Flag The "More" flag should not be used in GSMP. A request message with the Result field set to "More" SHOULD be answered with a failure response with a Code field indicating the type of failure. 3.1.1.2. SubMessage Number The definition of the SubMessage field should indicate if the submessages are numbered starting with 0 or 1. 3.1.1.3. I flag The value of the I flag for messages which are not segmented is unspecified. 3.1.1.4. Updated Messages The "Report Connection State Reply Message" and "All Ports Configuration Message" shoud be rewritten to use the I flag instead of the More flag. Kullgren, et. al. Expires August 2002 [Page 10] Internet Draft GSMP updates February 2002 3.1.1.5. Message Segmentation example A description of how to segment a message should be provided. The definition of the Length field should state if each segment should contain the total GSMP message length or the length of the segment. 3.1.2. Transaction Identifier The Transaction Identifier in [6] does not distinguish between replies from a request with "AckAll" and "NoSuccessAck". It also does not provide any information about how to handle replies where the Transaction ID doesn't match a Transaction ID from a previously sent request. If multiple controllers are connected to a single switch and the switch send an event message with "ReturnReceipt" set to all of them, there is no way for the switch to identify which controller the receipt is coming from. 3.2. Window Size The Switch Configuration Message defined in chapter 8.1 in [6] defines a Window size to be used by the controller when sending messages to the switch. It is not stated if this window should apply to all messages or only to messages that will always generate a reply. If messages that may not generate a reply should be counted against the window a time-out period when they are to be removed from the window should be defined. It is not defined if the the window should be cleared when the adjacency is lost and later recovered. 3.2.2. Retransmission A retransmission policy should be used if no reply is received for a message with "AckAll" set. Kullgren, et. al. Expires August 2002 [Page 11] Internet Draft GSMP updates February 2002 3.3. Delete Branches Message The "Delete Branch Element" has a 4 bit Error field that should be redefined to match the size of the "Failure Response Codes". 3.4. Adjacency The chapter about how to handle a new adjacency and re-established adjacencies should be clarified. 3.4.1. Loss of Synchronisation If a controller looses synchronisation, the draft requires the switch to reset the connection state This should be redefined since more than one controller may be synchronised to a switch partition. This change will affect the definition of the PFlag. 3.5. ReturnReceipt Result value in Events When the GSMP V3 initially was defined the events was supposed to be generated in a similar fashion as SNMP Traps. When an event was sent it was a uni-direction message and there was no requirement of the switch to verify that a controller received the message. Since event messages never expected a reply of a sent message there where no need of a Transaction Identifier. In the case of Event Messages the Transaction Identifier was decided it SHOULD be set to zero. Later on, a new Result Value of ReturnReceipt was introduced. ReturnReceipt is a results field used in Events to indicate that a switch requires an acknowledgment for the message. Introduced at the same time was the allowance of Multiple Controllers jointly controlling the same partition. Since all Transaction Identifiers is set to zero in the case of Event Messages the following problem can occur. 1. A switch has multiple controllers jointly controlling a partition. 2. The switch is configured to require acknowledgment of sent events. 3. For some reason one or more controller can not send the acknowledgment. 4. The switch has no ability to find out which controller that did not respond. Kullgren, et. al. Expires August 2002 [Page 12] Internet Draft GSMP updates February 2002 4. Additional Requirements 1. Better Slot/Port definition (Bay/Shelf also needed) 2. Better Bidirectional support Use in Move branch, Delete branch -- need atomic behavior 3. Better Port Capability identification (needed to find stack of supported TTP/CTPs) Should be consistent with Neighbor Capability Exchange approaches (i.e. LMP) Should be consistent with Link attributes used in Routing 4. Need to identify how to number points in the potential sub-multiplex tree Use convention in iftable? Or should points be refered to via root-ifindex:label, and partitioning instantiates new root-ifindexes? 5. Better Node Capability identification Support for LCAS? 6. Need to allow minimal Port configuration in addition to Matrix Connection configuration 7. How should blocking switch fabrics be handled? 8. Better Path Switching support Need to allow preconfiguration of selector allowing actions independant of controller 9. Rectify how B and R flags interact, since Bidirectional links are a fundamental unit in TDM nets 10.Remove "Layer specific" messages, i.e. ATM VPC Add/Move*/Delete Branch 11.Partitioning at "any layer" (not just port specific partitioning) 12.Generalize Statistics Messages (ie ATM vs Frame) 13.Clarify use of Port/Line Status so it corresponds w/ TDM Administrative/Operational state Clarify interaction with Port Up/Down Events 14.Support for transport over OSI TP1 or TP3, and SCTP 15.Need to correlate Events and only send root cause Event messages Kullgren, et. al. Expires August 2002 [Page 13] Internet Draft GSMP updates February 2002 5. Security Considerations The security of GSMP's TCP/IP control channel has been addressed in [10]. Any potential remaining security considerations are not addressed in the current revision of this draft. 6. Acknowledgements The list of authors provided with this document is a reduction of the original list. Currently listed authors wish to acknowledge that a substantial amount was also contributed to this work by: Avri Doria and Kenneth Sundell The authors would like to acknowledge the careful review and comments of Dimitri Papadimitriou and Torbjorn Hedqvist. Kullgren, et. al. Expires August 2002 [Page 14] Internet Draft GSMP updates February 2002 7. References [1] Ashwood-Smith, D., et. al., "Generalized MPLS - Signaling Functional Description", Internet Draft draft-ietf-mpls-generalized-signaling-07.txt, November 2001. Work in Progress. [2] Mannie, E., et. al., "Generalized Multi-Protocol Label Switching (GMPLS) Architecture", draft-ietf-ccamp-gmpls-architecture-01.txt (work in progress), November 2001 [3] Awduche, D, Rekhter, Y, et. al., "Multi-Protocol Lambda Switching: Combining MPLS Traffic Engineering Control with Optical Crossconnects," draft- awduche-mpls-te-optical-03.txt (work in progress), April, 2001 [4] Blake, S., et. al., _An Architecture for Differentiated Services_, RFC2475, December 1998 [5] Braden, R., _Integrated Services in the Internet Architecture: An Overview_, RFC1633, June 1994 [6] Doria, A, Sundell, K, Hellstrand, F, Worster, T, "General Switch Management Protocol V3," Internet Draft draft-ietf-gsmp-11.txt (work in progress), December 2001 [7] J. Wroclawski, "Specification of the Controlled-Load Network Element Service," RFC2211, Sep 1997. [8] Rajagopalan, B., et. al., _IP over Optical Networks: A Framework_, draft-many-ip-optical-framework- 03.txt (work in progress), March 2001 [9] Sjostrand, H, et al, Definitions of Managed Objects for the General Switch Management Protocol (GSMP)," Internet-Draft draft-ietf-gsmp-mib-07 (work in progress), November 2001. [10] Worster, T, et al, "GSMP Packet Encapsulations for ATM, Ethernet and TCP," Internet-Draft draft-ietf- gsmp-encaps-05 (work in progress), December 2001. [11] G.ASON _Architecture for the Automatic Switched Optical Kullgren, et. al. Expires August 2002 [Page 15] Internet Draft GSMP updates February 2002 Network_, Draft v0.5.1, June 2001 [12] Sadler, J., Mack-Crane, B., "Generalized Switch Management Protocol", draft-sadler-gsmp-tdm-labels-00.txt work in progress), February 2001 [13] Kompella, K., et. al., _Link Bundling in MPLS Traffic Engineering_, draft-ietf-mpls-bundle-01.txt (work in progress), November 2001 Kullgren, et. al. Expires August 2002 [Page 16] Internet Draft GSMP updates February 2002 8. Author's Addresses Hormuzd Khosravi Intel 2111 NE 25th Avenue Hillsboro, OR 97124 USA Phone: +1 503 264 0334 hormuzd.m.khosravi@intel.com Georg Kullgren Nortel Networks AB S:t Eriksgatan 115 A P.O. Box 6701 SE-113 85 Stockholm Sweden geku@nortelnetworks.com Jonathan Sadler Tellabs Operations, Inc. 1000 Remington Blvd Bolingbrook, IL 60440 Phone: +1 630-848-7741 Email: Jonathan.Sadler@tellabs.com Stephen Shew Nortel Networks PO Box 3511 Station C Ottawa, ON K1Y 4H7 sdshew@nortelnetworks.com Kohei Shiomoto Shiomoto.Kohei@lab.ntt.co.jp Atsushi Watanabe Nippon Telegraph and Telephone Corporation 807A 1-1 Hikari-no-oka, Yokosuka-shi Kanagawa 239-0847, Japan atsushi@exa.onlab.ntt.co.jp Satoru Okamoto Nippon Telegraph and Telephone Corporation 9-11 Midori-cho 3-chome, Musashino-shi Tokyo 180-8585, Japan okamoto@exa.onlab.ntt.co.jp Kullgren, et. al. Expires August 2002 [Page 17] Internet Draft GSMP updates February 2002 9. Full Copyright Statement "Copyright (C) The Internet Society 2001. 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 implmentation 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 Kullgren, et. al. Expires August 2002 [Page 18]