TEAS Working Group X. Zhang Internet-Draft H. Zheng, Ed. Intended Status: Informational Huawei Technologies Expires: July 30, 2017 R. Gandhi, Ed. Z. Ali Cisco Systems, Inc. P. Brzozowski ADVA Optical January 26, 2017 RSVP-TE Signaling Procedure for End-to-End GMPLS Restoration and Resource Sharing draft-ietf-teas-gmpls-resource-sharing-proc-08 Abstract In non-packet transport networks, there are requirements where Generalized Multi-Protocol Label Switching (GMPLS) end-to-end recovery scheme needs to employ restoration Label Switched Path (LSP) while keeping resources for the working and/or protecting LSPs reserved in the network after the failure occurs. This document reviews how the LSP association is to be provided using Resource Reservation Protocol - Traffic Engineering (RSVP-TE) signaling in the context of GMPLS end-to-end recovery scheme when using restoration LSP where failed LSP is not torn down. In addition, this document discusses resource sharing-based setup and teardown of LSPs as well as LSP reversion procedures. No new signaling extensions are defined by this document, and it is strictly informative in nature. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. 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." Zhang, et al Expires July 30, 2017 [Page 1] Internet-Draft GMPLS Restoration and Resource Sharing January 26, 2017 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. Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. 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 2. Conventions Used in This Document . . . . . . . . . . . . . . 4 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Acronyms and Abbreviations . . . . . . . . . . . . . . . . 4 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Examples of Restoration Schemes . . . . . . . . . . . . . 5 3.1.1. 1+R Restoration . . . . . . . . . . . . . . . . . . . 5 3.1.2. 1+1+R Restoration . . . . . . . . . . . . . . . . . . 5 3.1.2.1. 1+1+R Restoration - Variants . . . . . . . . . . . 6 3.2. Resource Sharing by Restoration LSP . . . . . . . . . . . 7 4. RSVP-TE Signaling Procedure . . . . . . . . . . . . . . . . . 8 4.1. Restoration LSP Association . . . . . . . . . . . . . . . 8 4.2. Resource Sharing-based Restoration LSP Setup . . . . . . . 8 4.3. LSP Reversion . . . . . . . . . . . . . . . . . . . . . . 10 4.3.1. Make-while-break Reversion . . . . . . . . . . . . . . 10 4.3.2. Make-before-break Reversion . . . . . . . . . . . . . 11 5. Security Considerations . . . . . . . . . . . . . . . . . . . 12 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 7.1. Normative References . . . . . . . . . . . . . . . . . . . 13 7.2. Informative References . . . . . . . . . . . . . . . . . . 13 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . 14 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 Zhang, et al Expires July 30, 2017 [Page 2] Internet-Draft GMPLS Restoration and Resource Sharing January 26, 2017 1. Introduction Generalized Multi-Protocol Label Switching (GMPLS) [RFC3945] defines a set of protocols, including Open Shortest Path First - Traffic Engineering (OSPF-TE) [RFC4203] and Resource ReserVation Protocol - Traffic Engineering (RSVP-TE) [RFC3473]. These protocols can be used to set up Label Switched Paths (LSPs) in non-packet transport networks. The GMPLS protocol extends MPLS to support interfaces capable of Time Division Multiplexing (TDM), Lambda Switching and Fiber Switching. These switching technologies provide several protection schemes [RFC4426][RFC4427] (e.g., 1+1, 1:N and M:N). Resource Reservation Protocol - Traffic Engineering (RSVP-TE) signaling has been extended to support various GMPLS recovery schemes, such as end-to-end recovery [RFC4872] and segment recovery [RFC4873]. As described in [RFC6689], an ASSOCIATION object with Association Type "Recovery" [RFC4872] can be signaled in the RSVP Path message to identify the LSPs for restoration. Also, an ASSOCIATION object with Association Type "Resource Sharing" [RFC4873] can be signaled in the RSVP Path message to identify the LSPs for resource sharing. [RFC6689] Section 2.2 reviews the procedure for providing LSP associations for GMPLS end-to-end recovery and Section 2.4 reviews the procedure for providing LSP associations for sharing resources. Generally GMPLS end-to-end recovery schemes have the restoration LSP set up after the failure has been detected and notified on the working LSP. For recovery scheme with revertive behavior, a restoration LSP is set up while working LSP and/or protecting LSP are not torn down in control plane due to a failure. In non-packet transport networks, as working LSPs are typically set up over preferred paths, service providers would like to keep resources associated with the working LSPs reserved. This is to make sure that the service can be reverted to the preferred path (working LSP) when the failure is repaired to provide deterministic behavior and guaranteed Service Level Agreement (SLA). In this document, we review procedures for GMPLS LSP associations, resource sharing based LSP setup, teardown, and LSP reversion for non-packet transport networks, including the following: o Review the procedure for providing LSP associations for the GMPLS end-to-end recovery using restoration LSP where working and protecting LSPs are not torn down and resources are kept reserved in the network after the failure. o In [RFC3209], the make-before-break (MBB) method assumes the old and new LSPs share the SESSION object and signal Shared Explicit Zhang, et al Expires July 30, 2017 [Page 3] Internet-Draft GMPLS Restoration and Resource Sharing January 26, 2017 (SE) flag in SESSION_ATTRIBUTE object for sharing resources. According to [RFC6689], an ASSOCIATION object with Association Type "Resource Sharing" in the Path message enables the sharing of resources across LSPs with different SESSION objects. The procedure for resource sharing using the SE flag in conjunction with an ASSOCIATION object is discussed in this document. o When using end-to-end recovery scheme with revertive behavior, methods for LSP reversion and resource sharing are summarized in this document. This document is strictly informative in nature and does not define any RSVP-TE signaling extensions. 2. Conventions Used in This Document 2.1. Terminology The reader is assumed to be familiar with the terminology in [RFC3209], [RFC3473], [RFC4872] and [RFC4873]. The terminology for GMPLS recovery is defined in [RFC4427]. 2.2. Acronyms and Abbreviations GMPLS: Generalized Multi-Protocol Label Switching LSP: An MPLS Label Switched Path MBB: Make Before Break MPLS: Multi-Protocol Label Switching RSVP: Resource ReSerVation Protocol SE: Shared Explicit flag TDM: Time Division Multiplexing TE: Traffic Engineering 3. Overview The GMPLS end-to-end recovery scheme, as defined in [RFC4872] and being considered in this document, switches normal traffic to an alternate LSP that is not even partially established only after the Zhang, et al Expires July 30, 2017 [Page 4] Internet-Draft GMPLS Restoration and Resource Sharing January 26, 2017 working LSP failure occurs. The new alternate route is selected at the LSP head-end node, it may reuse resources of the failed LSP at intermediate nodes and may include additional intermediate nodes and/or links. 3.1. Examples of Restoration Schemes Two forms of end-to-end recovery schemes, 1+R restoration and 1+1+R restoration are described in the following sections. Other forms of end-to-end recovery schemes also exist and they can use these signaling techniques. 3.1.1. 1+R Restoration One example of the recovery scheme considered in this document is 1+R recovery. The 1+R recovery scheme is exemplified in Figure 1. In this example, a working LSP on path A-B-C-Z is pre-established. Typically after a failure detection and notification on the working LSP, a second LSP on path A-H-I-J-Z is established as a restoration LSP. Unlike a protecting LSP which is set up before the failure, a restoration LSP is set up when needed, after the failure. +-----+ +-----+ +-----+ +-----+ | A +----+ B +-----+ C +-----+ Z | +--+--+ +-----+ +-----+ +--+--+ \ / \ / +--+--+ +-----+ +--+--+ | H +-------+ I +--------+ J | +-----+ +-----+ +-----+ Figure 1: An Example of 1+R Recovery Scheme During failure switchover with 1+R recovery scheme, in general, working LSP resources are not released so that working and restoration LSPs coexist in the network. Nonetheless, working and restoration LSPs can share network resources. Typically when the failure has recovered on the working LSP, the restoration LSP is no longer required and is torn down while the traffic is reverted to the original working LSP. 3.1.2. 1+1+R Restoration Another example of the recovery scheme considered in this document is 1+1+R. In 1+1+R, a restoration LSP is set up for the working LSP and/or the protecting LSP after the failure has been detected, and Zhang, et al Expires July 30, 2017 [Page 5] Internet-Draft GMPLS Restoration and Resource Sharing January 26, 2017 this recovery scheme is exemplified in Figure 2. +-----+ +-----+ +-----+ | D +-------+ E +--------+ F | +--+--+ +-----+ +--+--+ / \ / \ +--+--+ +-----+ +-----+ +--+--+ | A +----+ B +-----+ C +-----+ Z | +--+--+ +-----+ +-----+ +--+--+ \ / \ / +--+--+ +-----+ +--+--+ | H +-------+ I +--------+ J | +-----+ +-----+ +-----+ Figure 2: An Example of 1+1+R Recovery Scheme In this example, a working LSP on path A-B-C-Z and a protecting LSP on path A-D-E-F-Z are pre-established. After a failure detection and notification on the working LSP or protecting LSP, a third LSP on path A-H-I-J-Z is established as a restoration LSP. The restoration LSP in this case provides protection against failure of both the working and protecting LSPs. During failure switchover with 1+1+R recovery scheme, in general, failed LSP resources are not released so that working, protecting and restoration LSPs coexist in the network. The restoration LSP can share network resources with the working LSP, and it can share network resources with the protecting LSP. Typically, the restoration LSP is torn down when the traffic is reverted to the original LSP and it is no longer needed. There are two possible models when using a restoration LSP with 1+1+R recovery scheme: o A restoration LSP is set up after either a working or protecting LSP fails. Only one restoration LSP is present at a time. o A restoration LSP is set up after both working and protecting LSPs fail. Only one restoration LSP is present at a time. 3.1.2.1. 1+1+R Restoration - Variants Two other possible variants exist when using a restoration LSP with 1+1+R recovery scheme: Zhang, et al Expires July 30, 2017 [Page 6] Internet-Draft GMPLS Restoration and Resource Sharing January 26, 2017 o A restoration LSP is set up after either a working or protecting LSP fails. Two different restoration LSPs may be present, one for the working LSP and one for the protecting LSP. o Two different restoration LSPs are set up after both working and protecting LSPs fail, one for the working LSP and one for the protecting LSP. In all these models, if a restoration LSP also fails, it is torn down and a new restoration LSP is set up. 3.2. Resource Sharing by Restoration LSP +-----+ +-----+ | F +------+ G +--------+ +--+--+ +-----+ | | | | | +-----+ +-----+ +--+--+ +-----+ +--+--+ | A +----+ B +-----+ C +--X---+ D +-----+ E | +-----+ +-----+ +-----+ +-----+ +-----+ Figure 3: Resource Sharing in 1+R Recovery Scheme Using the network shown in Figure 3 as an example using 1+R recovery scheme, LSP1 (A-B-C-D-E) is the working LSP, and assume it allows for resource sharing when the LSP traffic is dynamically restored. Upon detecting the failure of a link along the LSP1, e.g. Link C-D, node A needs to decide which alternative path it will use to signal restoration LSP and reroute traffic. In this case, A-B-C-F-G-E is chosen as the restoration LSP path and the resources on the path segment A-B-C are re-used by this LSP. The working LSP is not torn down and co-exists with the restoration LSP. When the head-end node A signals the restoration LSP, nodes C, F, G and E reconfigure the resources (as listed in Table 1 of this document) to set up the LSP by sending cross-connection command to the data plane. In the recovery scheme employing revertive behavior, after the failure is repaired, the resources on nodes C and E need to be reconfigured to set up the working LSP (using a procedure described in Section 4.3 of this document) by sending cross-connection command to the data plane. The traffic is then reverted back to the original working LSP. Zhang, et al Expires July 30, 2017 [Page 7] Internet-Draft GMPLS Restoration and Resource Sharing January 26, 2017 4. RSVP-TE Signaling Procedure 4.1. Restoration LSP Association Where GMPLS end-to-end recovery scheme needs to employ a restoration LSP while keeping resources for the working and/or protecting LSPs reserved in the network after the failure, the restoration LSP is set up with an ASSOCIATION object that has Association Type set to "Recovery" [RFC4872], the Association ID and the Association Source set to the corresponding Association ID and the Association Source signaled in the Path message of the LSP it is restoring. For example, when a restoration LSP is signaled for a failed working LSP, the ASSOCIATION object in the Path message of the restoration LSP contains the Association ID and Association Source set to the Association ID and Association Source signaled in the working LSP for the "Recovery" Association Type. Similarly, when a restoration LSP is set up for a failed protecting LSP, the ASSOCIATION object in the Path message of the restoration LSP contains the Association ID and Association Source set to the Association ID and Association Source signaled in the protecting LSP for the "Recovery" Association Type. The procedure for signaling the PROTECTION object is specified in [RFC4872]. Specifically, the restoration LSP used for a working LSP is set up with P bit cleared in the PROTECTION object in the Path message of the restoration LSP and the restoration LSP used for a protecting LSP is set up with P bit set in the PROTECTION object in the Path message of the restoration LSP. 4.2. Resource Sharing-based Restoration LSP Setup GMPLS LSPs can share resources during LSP setup if they have Shared Explicit (SE) flag set in the SESSION_ATTRIBUTE objects [RFC3209] in the Path messages that create them and: o As defined in [RFC3209], LSPs have identical SESSION objects and/or o As defined in [RFC6689], LSPs have matching ASSOCIATION object with Association Type set to "Resource Sharing" signaled in their Path messages. LSPs in this case can have different SESSION objects i.e. different Tunnel ID, Source and/or Destination signaled in their Path messages. As described in [RFC3209], Section 2.5, the purpose of make-before- break is not to disrupt traffic, or adversely impact network operations while TE tunnel rerouting is in progress. In non-packet transport networks during the RSVP-TE signaling procedure, the nodes set up cross-connections along the LSP accordingly. Because the Zhang, et al Expires July 30, 2017 [Page 8] Internet-Draft GMPLS Restoration and Resource Sharing January 26, 2017 cross-connection cannot simultaneously connect a shared resource to different resources in two alternative LSPs, nodes may not be able to fulfill this request when LSPs share resources. For LSP restoration upon failure, as explained in Section 11 of [RFC4872], the reroute procedure may re-use existing resources. The action of the intermediate nodes during the rerouting process to reconfigure cross-connections does not further impact the traffic since it has been interrupted due to the already failed LSP. The node actions for setting up the restoration LSP can be categorized into the following: -----------------------------------+--------------------------------- | Category | Action | -----------------------------------+--------------------------------- | Reusing existing resource on | This type of node needs to | | both input and output interfaces | reserve the existing resources | | (nodes A & B in Figure 3). | and no cross-connection | | | command is needed. | -----------------------------------+--------------------------------- | Reusing existing resource only | This type of node needs to | | on one of the interfaces, either | reserve the resources and send | | input or output interfaces and | the re-configuration | | using new resource on the | cross-connection command to its| | other interfaces. | corresponding data plane | | (nodes C & E in Figure 3). | node on the interfaces where | | | new resources are needed and | | | it needs to re-use the existing| | | resources on the other | | | interfaces. | -----------------------------------+--------------------------------- | Using new resources on both | This type of node needs to | | interfaces. | reserve the new resources | | (nodes F & G in Figure 3). | and send the cross-connection | | | command on both interfaces. | -----------------------------------+--------------------------------- Table 1: Node Actions During Restoration LSP Setup Depending on whether the resource is re-used or not, the node actions differ. This deviates from normal LSP setup since some nodes do not need to re-configure the cross-connection. Also, the judgment whether the control plane node needs to send a cross-connection setup or modification command to its corresponding data plane node(s) relies on the check whether the LSPs are sharing resources. Zhang, et al Expires July 30, 2017 [Page 9] Internet-Draft GMPLS Restoration and Resource Sharing January 26, 2017 4.3. LSP Reversion If the end-to-end LSP recovery scheme employs the revertive behavior, as described in Section 3 of this document, traffic can be reverted from the restoration LSP to the working or protecting LSP after its failure is recovered. The LSP reversion can be achieved using two methods: 1. Make-while-break Reversion, where resources associated with a working or protecting LSP are reconfigured while removing reservations for the restoration LSP. 2. Make-before-break Reversion, where resources associated with a working or protecting LSP are reconfigured before removing reservations for the restoration LSP. In non-packet transport networks, both of the above reversion methods will result in some traffic disruption when the restoration LSP and the LSP being restored are sharing resources and the cross-connections need to be reconfigured on intermediate nodes. 4.3.1. Make-while-break Reversion In this reversion method, restoration LSP is simply requested to be deleted by the head-end. Removing reservations for restoration LSP triggers reconfiguration of resources associated with a working or protecting LSP on every node where resources are shared. The working or protecting LSP state was not removed from the nodes when the failure occurred. Whenever reservation for restoration LSP is removed from a node, data plane configuration changes to reflect reservations of working or protecting LSP as signaling progresses. Eventually, after the whole restoration LSP is deleted, data plane configuration will fully match working or protecting LSP reservations on the whole path. Thus reversion is complete. Make-while-break, while being relatively simple in its logic, has a few limitations as follows which may not be acceptable in some networks: o No rollback If for some reason reconfiguration of data plane on one of the nodes to match working or protecting LSP reservations fails, falling back to restoration LSP is no longer an option, as its state might have already been removed from other nodes. o No completion guarantee Zhang, et al Expires July 30, 2017 [Page 10] Internet-Draft GMPLS Restoration and Resource Sharing January 26, 2017 Deletion of an LSP provides no guarantees of completion. In particular, if RSVP packets are lost due to a node or link failure it is possible for an LSP to be only partially deleted. To mitigate this, RSVP could maintain soft state reservations and hence eventually remove remaining reservations due to refresh timeouts. This approach is not feasible in non-packet transport networks however, where control and data channels are often separated and hence soft state reservations are not useful. Finally, one could argue that graceful LSP deletion [RFC3473] would provide guarantee of completion. While this is true for most cases, many implementations will time out graceful deletion if LSP is not removed within certain amount of time, e.g. due to a transit node fault. After that, deletion procedures which provide no completion guarantees will be attempted. Hence, in corner cases a completion guarantee cannot be provided. o No explicit notification of completion to head-end node In some cases, it may be useful for a head-end node to know when the data plane has been reconfigured to match working or protecting LSP reservations. This knowledge could be used for initiating operations like enabling alarm monitoring, power equalization and others. Unfortunately, for the reasons mentioned above, make-while-break reversion lacks such explicit notification. 4.3.2. Make-before-break Reversion This reversion method can be used to overcome limitations of make-while-break reversion. It is similar in spirit to MBB concept used for re-optimization. Instead of relying on deletion of the restoration LSP, the head-end chooses to establish a new reversion LSP that duplicates the configuration of the resources on the working or protecting LSP, and uses identical ASSOCIATION and PROTECTION objects in the Path message of that LSP. Only if setup of this LSP is successful will other (restoration and working or protecting) LSPs be deleted by the head-end. MBB reversion consists of two parts: A) Make part: Creating a new reversion LSP following working or protecting LSP's path. The reversion LSP shares all of the resources of the working or protecting LSP and may share resources with the restoration LSP. As reversion LSP is created, resources are reconfigured to match its reservations. Hence, after reversion LSP is created, data plane configuration reflects working or protecting LSP reservations. B) Break part: Zhang, et al Expires July 30, 2017 [Page 11] Internet-Draft GMPLS Restoration and Resource Sharing January 26, 2017 After "make" part is finished, the original working or protecting and restoration LSPs are torn down, and the reversion LSP becomes the new working or protecting LSP. Removing reservations for working or restoration LSPs does not cause any resource reconfiguration on reversion LSP's path - nodes follow same procedures as for "break" part of any MBB operation. Hence, after working or protecting and restoration LSPs are removed, data plane configuration is exactly the same as before starting restoration. Thus, reversion is complete. MBB reversion uses make-before-break characteristics to overcome challenges related to make-while-break reversion as follow: o Rollback If "make" part fails, (existing) restoration LSP will still be used to carry existing traffic as the restoration LSP state was not removed. Same logic applies here as for any MBB operation failure. o Completion guarantee LSP setup is resilient against RSVP message loss, as Path and Resv messages are refreshed periodically. Hence, given that network recovers from node and link failures eventually, reversion LSP setup is guaranteed to finish with either success or failure. o Explicit notification of completion to head-end node Head-end knows that data plane has been reconfigured to match working or protecting LSP reservations on intermediate nodes when it receives Resv for the reversion LSP. 5. Security Considerations This document reviews procedures defined in [RFC3209] [RFC4872] [RFC4873] and [RFC6689] and does not define any new procedure. This document does not introduce any new security issues other than those already covered in [RFC3209] [RFC4872] [RFC4873] and [RFC6689]. 6. IANA Considerations This informational document does not make any request for IANA action. Zhang, et al Expires July 30, 2017 [Page 12] Internet-Draft GMPLS Restoration and Resource Sharing January 26, 2017 7. References 7.1. Normative References [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, December 2001. [RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. [RFC4872] Lang, J., Ed., Rekhter, Y., Ed., and D. Papadimitriou, Ed., "RSVP-TE Extensions in Support of End-to-End Generalized Multi-Protocol Label Switching (GMPLS) Recovery", RFC 4872, May 2007. [RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel, "GMPLS Segment Recovery", RFC 4873, May 2007. [RFC6689] L. Berger, "Usage of the RSVP ASSOCIATION Object", RFC 6689, July 2012. 7.2. Informative References [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching (GMPLS) Architecture", RFC 3945, October 2004. [RFC4203] Kompella, K., and Rekhter, Y., "OSPF Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4203, October 2005. [RFC4426] Lang, J., Rajagopalan, B., and Papadimitriou, D., "Generalized Multiprotocol Label Switching (GMPLS) Recovery Functional Specification", RFC 4426, March 2006. [RFC4427] Mannie, E., and Papadimitriou, D., "Recovery (Protection and Restoration) Terminology for Generalized Multi-Protocol Label Switching", RFC 4427, March 2006. Zhang, et al Expires July 30, 2017 [Page 13] Internet-Draft GMPLS Restoration and Resource Sharing January 26, 2017 Acknowledgements The authors would like to thank George Swallow for the discussions on the GMPLS restoration. The authors would like to thank Lou Berger for the guidance on this work. The authors would also like to thank Lou Berger, Vishnu Pavan Beeram and Christian Hopps for reviewing this document and providing valuable comments. A special thanks to Dale Worley for his thorough review of this document. Contributors Gabriele Maria Galimberti Cisco Systems, Inc. EMail: ggalimbe@cisco.com Zhang, et al Expires July 30, 2017 [Page 14] Internet-Draft GMPLS Restoration and Resource Sharing January 26, 2017 Authors' Addresses Xian Zhang Huawei Technologies F3-1-B R&D Center, Huawei Base Bantian, Longgang District Shenzhen 518129 P.R.China EMail: zhang.xian@huawei.com Haomian Zheng (editor) Huawei Technologies F3-1-B R&D Center, Huawei Base Bantian, Longgang District Shenzhen 518129 P.R.China EMail: zhenghaomian@huawei.com Rakesh Gandhi (editor) Cisco Systems, Inc. EMail: rgandhi@cisco.com Zafar Ali Cisco Systems, Inc. EMail: zali@cisco.com Pawel Brzozowski ADVA Optical EMail: PBrzozowski@advaoptical.com Zhang, et al Expires July 30, 2017 [Page 15]