SPRING Working Group                                             Y. Liu
Internet Draft                                             China Mobile
Intended status: Standards Track                                 C. Lin
Expires: 30 December 2025                          New H3C Technologies
                                                                S. Peng
                                                    Huawei Technologies
                                                                R. Chen
                                                        ZTE Corporation
                                                              G. Mishra
                                                           Verizon Inc.
                                                                 Y. Qiu
                                                   New H3C Technologies
                                                           30 June 2025


              Flexible Candidate Path Selection of SR Policy
           draft-liu-spring-sr-policy-flexible-path-selection-10


Abstract

   This document proposes a flexible SR policy candidate path selection
   method. Based on the real-time resource usage and forwarding quality
   of candidate paths, the head node can perform dynamic path switching
   among multiple candidate paths in the SR policy.

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
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   This Internet-Draft will expire on 30 December 2025.

Copyright Notice

   Copyright (c) 2025 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
   (https://trustee.ietf.org/license-info) in effect on the date of
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   publication of this document. Please review these documents
   carefully, as they describe your rights and restrictions with
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Table of Contents


   1. Introduction...................................................2
   2. Terminology....................................................3
   3. Background of requirements.....................................3
   4. Flexible Candidate Path Selection Method.......................5
      4.1. Threshold Parameters of Candidate Paths...................6
      4.2. Rules for Setting eligibility attribute...................8
      4.3. Flexible Candidate Path Selection Process.................8
   5. Usecases of Flexible Candidate Path Selection..................9
      5.1. Select the Best Path Based on End-to-End Delay............9
      5.2. Select the Best Path Based on Available Bandwidth........10
      5.3. Select the Best Path Based on Actual Bandwidth...........11
   6. IANA Considerations...........................................11
   7. Security Considerations.......................................11
   8. References....................................................12
      8.1. Normative References.....................................12
      8.2. Informative References...................................12
   9. Acknowledgments...............................................14
   Authors' Addresses...............................................14

1. Introduction

   Segment routing (SR) [RFC8402] is a source routing paradigm that
   explicitly indicates the forwarding path for packets at the ingress
   node. The ingress node steers packets into a specific path according
   to the Segment Routing Policy (SR Policy) as defined in [RFC9256].

   An SR Policy may have multiple candidate paths that are provisioned
   or signaled [I-D.ietf-idr-sr-policy-safi] [RFC8664] from one of more
   sources. The tie-breaking rules defined in [RFC9256] result in
   determination of a single "active path" in a formal definition.

   Refer to [RFC9256] only the active candidate path MUST be used for
   forwarding traffic that is being steered onto that policy except for
   certain scenarios such as fast reroute where a backup candidate path
   may be used. A candidate path can be represented as a segment list
   or a set of segment lists. If a set of segment lists is associated
   with the active path of the policy, then the steering is per flow
   and weighted-ECMP (W-ECMP) based according to the relative weight of
   each valid segment list.


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   According to the criteria for the validity of candidate paths
   described in Section 5 of [RFC9256], if there is a valid segment
   list in the active candidate path, the active candidate path is
   still valid. When some segment lists of the active candidate path
   are invalid, the active candidate path may still be valid, but it
   may not continue to meet the actual forwarding requirements.

   [I-D.karboubi-spring-sr-policy-eligibility] introduces a concept of
   an eligibility attribute at the candidate path level, not only at
   the time of the computation but also through topology and network
   changes to ensure that user intentions are preserved while carrying
   service traffic.

   This document proposes a method for setting the eligibility
   attribute, which can influence the selection of candidate paths. For
   specific preference rules, refer to [I-D.karboubi-spring-sr-policy-
   eligibility].

   Based on real-time resource usage and forwarding quality of
   candidate paths, the head node can dynamically adjust
   the eligibility attribute value, enabling it to perform dynamic path
   switching among multiple candidate paths within the SR policy.

   [RFC2386] provides valuable background on QoS-based routing, details
   some issues and requirements associated with QoS-based routing, and
   proposes a framework for employing QoS-based routing within the
   Internet. This document describes an SR Policy mechanism where the
   path state is switched based on the resource status of the traversed
   path. However, it does not address the challenges related to dynamic
   distributed scheduling or resource reservation along intermediate
   paths. The document specifies the capability to switch to
   alternative paths within a strategy when the current path fails to
   satisfy designated link quality criteria, such as bandwidth, delay,
   or packet loss. In instances where a controller issues an SR Policy
   encompassing multiple paths, should a path's link quality not meet
   the established requirements, a switch to a backup path for
   forwarding is executed.

2. Terminology

   The definitions of the basic terms are identical to those found in
   Segment Routing Policy Architecture [RFC9256].

3. Background of requirements

   When some segment lists of the active candidate path are invalid,
   according to [RFC9256], if there is a valid segment list in the
   active candidate path, the active candidate path is still valid. But
   the paths of remaining segment lists may not meet the SR policy
   forwarding performance requirements, such as insufficient path
   bandwidth. Even if there are other candidate paths with lower
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   preference that can meet the forwarding performance requirements in
   the SR policy, the traffic will continue to be forwarded along the
   original active candidate path.

   As an example, consider the following SR Policy to illustrate the
   issues present in the current candidate path selection process in
   detail.

      SR Policy POL1
         Candidate Path CP1
            Preference 200
            Segment List 1 <SID11...SID1i>, Weight 1
            Segment List 2 <SID21...SID2j>, Weight 1
            Segment List 3 <SID31...SID3k>, Weight 1
         Candidate Path CP2
          Preference 100
            Segment List 4 <SID41...SID4i>, Weight 1
            Segment List 5 <SID51...SID5j>, Weight 1
            Segment List 6 <SID61...SID6k>, Weight 1

   There are two static candidate paths CP1 and CP2 in SR policy POL1.
   CP1 has a higher preference. Both candidate paths are composed of
   three static segment lists with the same weight. The path indicated
   by each segment list can carry traffic of 100Mbps bandwidth. When
   all Segment Lists in CP1 are valid, the effective bandwidth of the
   candidate path is 300Mbps.

   The bandwidth of the actual traffic forwarded by the SR policy is
   between 100Mbps and 150Mbps. Because the traffic forwarded on the
   candidate path will share the load on the three segment list paths
   according to the weight value. Therefore, normally, the candidate
   path can meet the forwarding requirements. The traffic is forwarded
   on the three segment lists of the high preference candidate paths of
   the SR policy.

   When the segment list 1 and 2 in the high-preference candidate path
   CP1 are invalid, according to the candidate path validity criteria
   described in [RFC9256] Section 5, because the segment list 3 in CP1
   is still valid, the active candidate path CP1 is still valid. All
   traffic of SR policy POL1 will continue to be forwarded through the
   path of CP1. However, because segment list 3 can only forward
   100Mbps traffic, over-bandwidth traffic will be discarded.

   Of course, when the Segment List path fault is detected, the network
   device can report the detected fault information to the controller.
   The controller optimizes the forwarding path after receiving the
   message. However, this interaction process is relatively long, and
   it is difficult to meet the requirement for fast switching.

   When the quality of high-preference candidate paths deteriorates,
   due to issues such as insufficient available bandwidth, increased
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   end-to-end transmission delay, or segment lists that fail to meet
   service requirements, the same need arises. The goal is to switch
   traffic to other candidate paths within the SR policy that better
   satisfy the forwarding quality requirements.

   To address this issue, this document proposes a new candidate path
   selection rule that defines resource thresholds and forwarding
   quality requirements for candidate paths.

   If a candidate path does not satisfy the forwarding quality
   requirements, its eligibility attribute MUST be set to false. During
   the active CP selection process, the head-end SHALL use this
   eligibility attribute as an additional mandatory criterion, in
   conjunction with the rules defined in [RFC9256], Section 2.9. When a
   CP's eligibility attribute is false, it indicates that the path
   cannot forward traffic and therefore MUST NOT be considered for
   active CP selection.

4. Flexible Candidate Path Selection Method

   As described in [RFC9256], the candidate path selection process
   operates primarily on the candidate path Preference. A candidate
   path is selected when it is valid and it has the highest Preference
   value among all the valid candidate paths of the SR Policy.

   [I-D.karboubi-spring-sr-policy-eligibility] introduce a new
   attribute at the candidate path level called eligibility. Only
   candidate paths with eligibility as true must be considered as part
   of the active candidate path selection defined in [RFC9256].

   This document proposes using forwarding quality
   requirements and resource requirements of candidate paths
   as eligibility criteria for path selection.

   A headend MAY be informed about the forwarding quality requirements
   of a candidate path for an SR Policy <Color, Endpoint> through
   various means, including configuration, PCEP, or BGP. The extensions
   of BGP and PCEP are described in

   [I-D.liu-idr-bgp-sr-policy-cp-threshold] and

   [I-D.liu-pce-sr-policy-cp-threshold].

   When a candidate path fails to meet forwarding quality requirements,
   its eligibility attribute should be set to false, thereby excluding
   it from active candidate path selection.

   For candidate paths containing multiple segment lists:

   - If a segment list fails to meet forwarding quality requirements,
      it should be excluded from forwarding operations.
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   - When all segment lists under a candidate path fail to meet
      forwarding quality requirements, the path's eligibility attribute
      should be set to false, subsequently disqualifying it from active
      candidate path selection.

4.1. Threshold Parameters of Candidate Paths

   The threshold parameters of candidate paths can include but are not
   limited to the following:

   *  Jitter

   *  Latency

   *  Packet loss

      Delay, jitter, and packet loss are thresholds at the segment list
      level.

      When the jitter, delay, or packet loss of a valid segment list
      does not meet the specified threshold requirements, the segment
      list will be deemed invalid and will no longer participate in

      load sharing traffic.

   *  Available bandwidth

      The bandwidth threshold is the threshold at the candidate path
      level.

      CP available bandwidth = CP preset bandwidth * (Sum of Segment
      List weights in Up state / Sum of all Segment List weights)

   *  Actual bandwidth

      The actual bandwidth refers to the sum of the actual available
      remaining bandwidth of each valid segment list in the candidate
      path.

      Due to the different congestion conditions of each node on the
      forwarding path, the actual bandwidth that can forward service
      packets may differ from the preset bandwidth. By utilizing some
      measurement mechanisms, the actual minimum available bandwidth

      and actual minimum remaining bandwidth of all nodes along the

      path can be obtained. The specific measurement mechanism is not
      within the scope of this document.

   *  Precision Availability Metrics (PAM)

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      Consider a candidate path of SR policy as a Service Level
      Objective (SLO), based on the Precision Availability Metrics

      (PAM) defined in [RFC9544], determine whether the candidate path
      meets the forwarding requirements.

   If both segment list-level thresholds (such as latency, jitter, or
   packet loss) and candidate path-level thresholds (such as available
   bandwidth) are specified, then when one or more segment lists in the
   candidate path fail to meet the segment list-level thresholds, it
   indicates that these segment lists cannot provide forwarding
   capabilities that meet the SLA requirements. These segment lists
   will be marked as unavailable and will no longer participate in
   packet forwarding. After excluding these segment lists, it should be
   verified whether the candidate path still meets the forwarding
   quality requirements. If it does, traffic can continue to be
   forwarded along that candidate path.

   For example, two threshold parameters, delay and available
   bandwidth, are specified simultaneously for the candidate path with
   multiple segment lists. When the delay of a segment list exceeds the
   threshold, the following processing is performed:

   1) Remove the segment list from the forwarding path first.

   2) Calculate the current available bandwidth of CP based on the
      weight ratio of the remaining effective segment lists and the
      bandwidth of CP.

   3) Check whether the current available bandwidth of CP still meets
      the bandwidth threshold requirements.

      *  If the available bandwidth still meets the requirements, the
         candidate path still meets the forwarding quality

         requirements, and the traffic is still forwarded along this
         candidate path.

      *  Otherwise, set the eligibility attribute of this CP to false.
         The system should then consider switching service traffic to
         another active candidate path with better forwarding quality.
   If the candidate path does not specify any threshold parameters,
   select the primary candidate path according to the selection method
   defined in [RFC9256].

   By default, there is no threshold parameter specified on the
   candidate path.


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4.2. Rules for Setting eligibility attribute

   When a candidate path's current forwarding quality meets specified
   threshold requirements, its eligibility attribute MUST be set
   to true, indicating this path is valid for:

      *  Traffic forwarding operations.

      *  Active candidate path selection (per [RFC9256] selection
         methodology)

   Conversely, when a candidate path fails to meet quality
   requirements, its eligibility attribute MUST be set to false.

   For candidate paths without defined threshold parameters:

      *  The eligibility attribute MUST default to true.

      *  Primary path selection follows [RFC9256] procedures.

   When multiple eligible candidate paths coexist in an SR policy:

      *  Only paths with eligibility=true MAY participate in active

         path selection.

      *  Detailed behavior specified in

         [I-D.karboubi-spring-sr-policy-eligibility].

4.3. Flexible Candidate Path Selection Process

   The process of selecting the best candidate path for SR policy
   through the threshold parameter of the candidate path is as follows.

   1) Configure the threshold parameters on the candidate path of the
      head node through static manual configuration or controller
      distribution.

   2) The head node monitors whether the available resources and
      forwarding quality of the SR policy candidate path exceed the
      thresholds.

   3) The forwarding quality of path can be obtained through active or
      passive performance measurement methods, such as iOAM [RFC9378],
      STAMP [I-D.ietf-spring-stamp-srpm], TWAMP [RFC5375], etc. The
      real-time quality data can be calculated by the controller and
      distributed to the head node, or calculated by the head node
      according to the network measurement data. The measurement method
      and quality data acquisition method are beyond the scope of this
      document.
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   4) According to the rules described in Section 4.2, when the
      available resources are less than the threshold, or the
      forwarding quality cannot meet the threshold requirements, select
      a new active candidate path.

   5) After the old active candidate path eliminates the fault or
      improves the forwarding quality, whether to recover can be
      specified by the configuration. If fault recovery is required,
      start a wait timer for delay recovery. When the timer expires and
      the old active candidate path still meets the threshold
      requirements, the traffic will be switched to the old higher
      preference candidate path.

   For avoiding path switching frequently, both over-threshold
   switching and fault recovery should be delayed. The interval of
   delay waiting can be adjusted by configuration.

5. Usecases of Flexible Candidate Path Selection

   The SR policy in Section 3 is still used to illustrate how the
   flexible candidate path selection method switches candidate paths.

   SR policy POL1 has two candidate paths CP1 and CP2. The Preference
   of CP1 is 200, and the Preference of CP2 is 100. Both candidate
   paths are composed of three segment lists with the same weight.

5.1. Select the Best Path Based on End-to-End Delay

   The quality requirement for the services carried on the SR policy is
   that the transmission delay must be less than 200ms. The bandwidth
   of the actual traffic forwarded by the SR policy is between 100Mbps
   and 150Mbps.

   When the delay of Segment List 1 does not meet the requirements,
   continue to check the available bandwidth of CP1. Due to segment
   list 2 only having 100Mbps bandwidth, it cannot meet the actual
   traffic forwarding requirements. CP1's eligibility attribute MUST be
   set to false, triggering the selection of CP2 as POL1's new active
   candidate path. The traffic forwarded by POL1 is switched to the
   path of CP2 for forwarding.

      SR Policy POL1
        Candidate Path CP1
           Preference 200
           Delay threshold 200ms //Delay<=200ms
           Segment List 1 <SID11...SID1i>, Weight 1 //100M, Delay>1s
           Segment List 2 <SID21...SID2i>, Weight 1 //100M, Delay<100ms
        Candidate Path CP2
           Preference 100
           Delay threshold 200ms  //Delay<=200ms
           Segment List 3 <SID31...SID3i>, Weight 1 //100M, Delay<100ms
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           Segment List 4 <SID41...SID4i>, Weight 1 //100M, Delay<100ms

5.2. Select the Best Path Based on Available Bandwidth

   The preset bandwidth for CP1 and CP2 is both 300Mbps. Each segment
   list can carry a maximum of 100Mbps traffic. The quality requirement
   for service traffic is that the available bandwidth of the
   forwarding path must not be less than 150Mbps.

      SR Policy POL1
         Candidate Path CP1
            Preference 200
            Preset bandwidth 300Mbps
            Available bandwidth threshold 150Mbps
            Segment List 1 <SID11...SID1i>, Weight 1
            Segment List 2 <SID21...SID2j>, Weight 1
            Segment List 3 <SID31...SID3k>, Weight 1
         Candidate Path CP2
          Preference 100
            Preset bandwidth 300Mbps
          Available bandwidth threshold 150Mbps
            Segment List 4 <SID41...SID4i>, Weight 1
            Segment List 5 <SID51...SID5j>, Weight 1
            Segment List 6 <SID61...SID6k>, Weight 1

   First, take the available bandwidth as the threshold parameter of
   POL1. The threshold for configuring the available bandwidth is
   150Mbps. When the available bandwidth of the candidate path is less
   than 150Mbps, perform path switching.

   Normally, the three segment lists of CP1 and CP2 are valid. The
   available bandwidth of CP1 is 300Mbps, and the available bandwidth
   can meet the threshold requirements. CP1's eligibility attribute
   MUST be set to true, CP1 is selected as the active candidate path
   according to the Preference.

   If the paths indicated by Segment List 1 and 2 fail, Segment List 1
   and 2 become invalid, and the available bandwidth of CP1 becomes
   100Mbps. Because the available bandwidth of CP1 is lower than the
   specified threshold, CP1 has failed to meet the forwarding quality
   requirements. CP1's eligibility attribute MUST be set to false. Need
   to reselect the active candidate path for POL1.

   The three segment lists of the low-preference candidate path CP2 of
   POL1 are valid, and the available bandwidth can meet the threshold
   requirements. CP2's eligibility attribute MUST be set to true. CP2
   is selected as the new active candidate path of POL1. The traffic
   forwarded by POL1 will switch to the path of CP2 for forwarding.




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5.3. Select the Best Path Based on Actual Bandwidth

   In scenarios involving the actual available bandwidth measurement
   method for SRv6, as described in

   [I-D.liu-ippm-srv6-bandwidth-measurement], the quality requirement
   for the services carried on the SR policy mandates that the actual
   available bandwidth of the forwarding path must exceed 80 Mbps. If
   traffic congestion occurs on a node in Segment List 1, resulting in
   a maximum forwarding capacity of only 50 Mbps for service traffic,
   and if Segment List 2 is either in a down state or has exceeded the
   delay threshold, Segment List 2 will not participate in load sharing
   traffic.

   When the aggregate available bandwidth of CP1 falls below 80 Mbps:

      *  CP1's eligibility attribute MUST be set to false.

      *  CP2's eligibility attribute MUST be set to true (provided it
         meets forwarding requirements).

      *  CP2 SHALL become POL1's new active candidate path.

      SR Policy POL1
        Candidate Path CP1
           Preference 200
            Preset bandwidth 200Mbps
           Actual available bandwidth threshold 80Mbps
            Segment List 1 <SID11...SID1i>, Weight 1
               (Actual available bandwidth is only 50Mbps.)
            Segment List 2 <SID21...SID2j>, Weight 1
               (In Down state, or the delay has exceeded the threshold.)
        Candidate Path CP2
           Preference 100
           Preset bandwidth 300Mbps
           Actual available bandwidth threshold 80Mbps
            Segment List 3 <SID41...SID4i>, Weight 1 (100Mbps)
            Segment List 4 <SID51...SID5j>, Weight 1 (100Mbps)
            Segment List 5 <SID61...SID6k>, Weight 1 (100Mbps)

   The traffic forwarded by POL1 will switch to the path of CP2 for
   forwarding.

6. IANA Considerations

   This document has no IANA actions.

7. Security Considerations

   This document does not introduce any security considerations.


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8. References

8.1. Normative References

   [I-D.ietf-idr-sr-policy-safi] Previdi, S., Filsfils, C., Talaulikar,
             K., Mattes, P., and Jain, D., "Advertising Segment Routing
             Policies in BGP", draft-ietf-idr-sr-policy-safi-13 (work
             in progress), February 2025.

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, DOI
             10.17487/RFC2119, March 1997, <https://www.rfc-
             editor.org/info/rfc2119>.

   [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
             Decraene, B., Litkowski, S., and R. Shakir, "Segment
             Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,July
             2018, <https://www.rfc-editor.org/info/rfc8402>.

   [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
             2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
             May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
             Hardwick, J., "Path Computation Element Communication
             Protocol (PCEP) Extensions for Segment Routing", RFC8664,
             DOI 10.17487/RFC8664, December 2019, <https://www.rfc-
             editor.org/info/rfc8664>.

   [RFC9256] Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
             P. Mattes, "Segment Routing Policy Architecture", RFC
             9256, DOI 10.17487/RFC9256, July 2022, <https://www.rfc-
             editor.org/info/rfc9256>.

8.2. Informative References

   [I-D.liu-idr-bgp-sr-policy-cp-threshold] Liu, Y., Lin, C., Qiu,
             Y., " BGP Extension for Distributing CP Threshold
             Constraints of SR Policy", draft-liu-idr-bgp-sr-policy-cp-
             threshold-02 (work in progress), November 2024.

   [I-D.liu-pce-sr-policy-cp-threshold] Liu, Y., Lin, C., Qiu, Y., "
             PCEP Extension to Support Signaling Candidate Path
             Threshold Constraints of SR Policy", draft-liu-pce-sr-
             policy-cp-threshold-03 (work in progress), February 2025.

   [I-D.liu-ippm-srv6-bandwidth-measurement] Liu, Y., Lin, C., Qiu, Y.,
             Liu, Y., Liang, Y., " Measurement Method for Bandwidth of
             SRv6 Forwarding Path", draft-liu-ippm-srv6-bandwidth-
             measurement (work in progress), November  2024.

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   [I-D.karboubi-spring-sr-policy-eligibility] Karboubi, A., Shah, H.,
             Sivalaban, S., Stone, A. and Schmutz, C., "Eligibility
             Concept in Segment Routing Policies", draft-karboubi-
             spring-sr-policy-eligibility-02 (work in progress), June
             2025.

   [I-D.ietf-spring-stamp-srpm] Gandhi, R., Filsfils, C., Janssens, B.,
             Chen, M., and R.F. Foote, "Performance Measurement Using
             Simple Two-Way Active Measurement Protocol (STAMP) for
             Segment Routing Networks", Work in Progress, Internet-
             Draft, draft-ietf-spring-stamp-srpm-19, 20 June 2025,
             <https://datatracker.ietf.org/doc/html/draft-ietf-spring-
             stamp-srpm-19>.

   [RFC2386] Crawley, E., Nair, R., Rajagopalan, B. and H. Sandick, "A
             Framework for QoS-based Routing in the Internet", RFC
             2386, August 1998.

   [RFC5375] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., Babiarz,
             J., "A Two-Way Active Measurement Protocol (TWAMP)", RFC
             5375, DOI 10.17487/RFC5375, October 2008,
             <https://www.rfc-editor.org/info/rfc5375>.



   [RFC9378] Brockners, F., Bhandari, S., Bernier, D., Mizrahi, T., "In
             Situ Operations, Administration, and Maintenance (IOAM)
             Deployment", RFC 9378, DOI 10.17487/RFC9378, April 2023,
             <https://www.rfc-editor.org/info/rfc9378>.

   [RFC9544] Mirsky, G., Halpern, J., Min, X., Clemm, A., Strassner,
             J., Francois, J., "Precision Availability Metrics for
             Services Governed by Service Level Objectives (SLOs)", RFC
             9544, DOI 10.17487/RFC9544, March 2024, <https://www.rfc-
             editor.org/info/rfc9544>.















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9. Acknowledgments

   The authors would like to thank the following for their valuable
   contributions of this document:

   TBD

Authors' Addresses

   Yisong Liu
   China Mobile
   Beijing
   China

   Email: liuyisong@chinamobile.com

   Changwang Lin
   New H3C Technologies
   Beijing
   China

   Email: linchangwang.04414@h3c.com

   Shuping Peng
   Huawei Technologies
   Beijing
   China
   Email: pengshuping@huawei.com

   Ran Chen
   ZTE Corporation
   Nanjing
   China
   Email: chen.ran@zte.com.cn

   Gyan S. Mishra
   Verizon Inc.
   Email: gyan.s.mishra@verizon.com

   Yuanxiang Qiu
   New H3C Technologies
   Beijing
   China

   Email: qiuyuanxiang@h3c.com






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