IDR Working Group                                   G. Van de Velde, Ed.
Internet-Draft                                                     Nokia
Intended status: Standards Track                                K. Patel
Expires: March 3, June 23, 2018                                            Arrcus
                                                                   Z. Li
                                                     Huawei Technologies
                                                         August 30,
                                                       December 20, 2017

                    Flowspec Indirection-id Redirect
                draft-ietf-idr-flowspec-path-redirect-02
                draft-ietf-idr-flowspec-path-redirect-03

Abstract

   This document defines a new extended community known as flowspec
   redirect-to-indirection-id.  This extended community triggers
   advanced redirection capabilities to flowspec clients.  When
   activated, this flowspec extended community is used by a flowspec
   client to find the correct corresponding next-hop information within a localised
   indirection-id mapping table.

   The functionality detailed in this document allows a network
   controller to decouple the BGP flowspec redirection instruction from
   the actual selected redirection path selected. itself.

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 [1].

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/. https://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 March 3, June 23, 2018.

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)
   (https://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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  indirection-id and indirection-id table . . . . . . . . . . .   3
   3.  Use Case Scenarios  . . . . . . . . . . . . . . . . . . . . .   4   3
     3.1.  Redirection shortest Path tunnel  . . . . . . . . . . . .   4   3
     3.2.  Redirection to path-engineered tunnels  . . . . . . . . .   5   4
     3.3.  Redirection to complex dynamically constructed tunnels  .   6   5
   4.  Redirect to indirection-id  redirect-to-indirection-id Community  . . . . . . . . . . . .   7   6
   5.  Redirect using localised indirection-id mapping table . . . .   8
   6.  Validation Procedures . . . . . . . . . . . . . . . . . . . .   9   8
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   9.  Contributor Addresses . . . . . . . . . . . . . . . . . . . .   9
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  11
     11.2.  Informative References . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   Flowspec is an extension to BGP that allows for the dissemination of
   traffic flow specification rules.  This has many possible
   applications but the primary one for many network operators is the
   distribution of traffic filtering actions for DDoS mitigation.  The
   flow-spec standard RFC5575 [2] defines a redirect-to-VRF action for
   policy-based forwarding forwarding, but this mechanism is not always sufficient,
   particularly if the redirected traffic needs to be steered onto an
   explicite path.

   Every flowspec policy route is effectively a rule, consisting of a
   matching part (encoded two
   parts.  The first part, encoded in the NLRI field) and an action part (encoded field, provides
   information about the traffic matching the policy rule. the second
   part, encoded in one or more BGP extended communities). communities, provides
   policy instructions for traffic handling on the flowspec client.  The flow-spec
   flowspec standard RFC5575 [2] defines widely-used filter actions such
   as discard and rate limit; it also defines a redirect-to-VRF action
   for policy-based forwarding.  Using the redirect-to-VRF action to
   steer traffic towards an alternate destination is useful for DDoS mitigation but
   mitigation, however using this technology methodology can be cumbersome when
   there is need to steer the traffic onto an explicitely defined
   traffic path.

   This draft proposes specifies a new redirect-to-indirection-id flowspec action
   making use of a 32-bit indirection-id within using a new extended community.
   Each indirection-id serves as anchor point, for policy-
   based policy-based
   forwarding onto an explicite path on by a flowspec client.

   A flowspec based indirection service plane can be create when a
   single 32-bit flowspec indirection-id maps towards a pool of
   explicite paths.

2.  indirection-id and indirection-id table

   The indirection-id is a 32-bit unsigned number, used as anchor point
   on a flowspec client.  The indirection-id is on a flowspec client the
   lookup key-value within a localised list of potential indirection
   paths.  The indirection-id will allow the flowspec client to steer
   traffic to a particular path or into for policy-based forwarding onto an indirection service plane explicite
   path by
   doing a recursive key-value lookup. flowspec client.

   The indirection-id table is the table containing an ordered list construct of indirection-id key-values,
   values, ordered by indirection-id type; where each
   key-value maps towards a particular path or set of paths.  The
   indirection-id type MAY provide additional context about the
   indirection-id 32-bit value.  The flowspec client MUST use the
   indirection-id as key-value within the indirection-id type
   corresponding indirection-id type.  Each entry in this table to locate the explicite path and
   corresponding next-hop information.
   contains policy-based forwarding instructions.

   The configuration of the indirection-id table on a flowspec client is
   localised on each router and MAY happen out-of-band from BGP flowspec and is a localised construct
   on each router.
   flowspec.  For some use-case scenarios the indirection-id type
   provides additional (maybe even fully sufficient) context towards for a
   flowspec client to deduct automatic, without explicite out-of-band
   configuration, the for policy based forwarding, making a localized
   indirection-id table. table obsolete.  For example, when the indirection-id
   refers to a MPLS segment routing node-id [6], then
   indirection-id type can provide the flowspec client the awareness
   that the indirection-id is
   provides sufficient information for a segment routing node-id.  For this
   example the indirection-id type allows the flowspec clients to do a
   recursive lookup using traditional segment routing technology.

   To summarise, each indirection-id key-value entry in on the indirection-
   table maps recursively to sufficient next-hop information (parameters
   regarding encapsulation, egress-interface, QoS, etc...) to
   successfully indirect traffic according
   flowspec controller
   expectations. client.

3.  Use Case Scenarios

   This section describes a few use-case scenarios when deploying redirect-to-
   indirection-id.
   redirect-to-indirection-id.

3.1.  Redirection shortest Path tunnel

   Description:

   The first use-case describes an example where a single flowspec route
   is sent from a BGP flowspec controller to many BGP flowspec clients.
   This BGP flowspec route carries the redirect-to-indirection-id to all
   flowspec clients to redirect matching dataflows onto a shortest-path
   tunnel pointing towards a single remote destination.

   For

   In this first use-case scenario, each flowspec client receives
   flowspec routes.  The received flowspec routes have the extended redirect-to-
   indirection-id
   redirect-to-indirection-id community attached.  Each redirect-to-indirection-id redirect-to-
   indirection-id community embeds two relevant components: (1) 32-bit
   indirection-id
   key-value and (2) indirection-id type.  The indirection-id type is
   used to identify the corresponding indirection-id table, and the
   actual 32-bit indirection-id key-value is used within the
   indirection-id table to locate  These two components
   provide the corresponding next-hop
   information.  The finite result of this operation is flowspec client with sufficient
   tunnel encapsulation information for policy
   based forwarding to forward steer and encapsulate the data-
   packet data-packet accordingly
   to a remote shortest path tunnel to a remote end-point.

   Requirements:

   For redirect to shortest path tunnel it is required that the tunnel
   MUST be up-and-running operational and allow packets to be unidirectional
   exchanged steered over the shortest
   path between tunnel head- and tail-end.

   Example: Indirection-ID community types to be used:

   o  0 (localised ID): When the intent is to use a localised
      Indirection-id table on the flowspec client.  This requires out-
      of-band configuration of the indirection-id table table, configured through out-of-band procedures.

   o  1 or 2 (Node ID): When ID's): This type can be used when the intent goal is to use a Segment Routing
      MPLS based
      Indirection-id table on the flowspec client.  This requires that Segment Routing is enabled on towards a remote destination.  In this
      use-case scenario the flowspec client. rule contains a SR (Segment
      Routing) node SID to steer traffic towards.

3.2.  Redirection to path-engineered tunnels

   Description:

   The second use-case describes an example where a single flowspec
   route is sent from a BGP flowspec controller to many BGP flowspec
   clients.  This BGP flowspec route carries the redirect-to-
   indirection-id extended community to all flowspec clients with
   instructions policy information to redirect matching dataflows onto steer
   traffic upon a path engineered path-engineered tunnel.  It is expected assumed that each of the path
   engineered tunnels is
   instantiated by out-of-band configuration and can be uniquely
   identified by the combination of (1) indirection-id 32-bit key-value
   and (2) indirection-id type.

   For this second use-case scenario, each flowspec client receives
   flowspec routes.  The flowspec routes have the extended redirect-to-
   indirection-id community attached.  Each redirect-to-indirection-id
   community embeds two relevant components similar as explained in
   previous use-case.  However the finite result of this operation is
   sufficient tunnel encapsulation information to forward and
   encapsulate the data-packet accordingly to a remote tunnel end-point are configured using a path engineered tunnel construction. out-of-band from BGP
   flowspec.

   Segment Routing Example:

   For this example the indirection-id type informs the flowspec client
   that the indirection-id 32-bit key-value references points towards a Segment
   Routing Binding SID.  The Binding SID is a segment identifier value
   (as per segment routing definitions in [I-D.draft-ietf-spring-segment-
   routing] [I-D.draft-ietf-spring-
   segment-routing] [6]) used to associate an explicit path.  The
   Binding SID and corresponding path engineered tunnel can may for example
   be setup by a controller using BGP as specified in [I-D.sreekantiah-idr-segment-
   routing-te] [I-D.sreekantiah-
   idr-segment-routing-te] [5] or alternatly by using PCEP as detailed
   in draft-ietf-pce-
   segment-routing draft-ietf-pce-segment-routing [7].  To conclude, when a BGP
   speaker at some point in time receives a flow-spec route with an
   extended 'redirect-to-
   indirection-id' 'redirect-to-indirection-id' community, it installs a traffic filtering
   policy-based forwarding rule that
   matches particular to redirect packets and redirects them onto an explicit
   path associated with the corresponding Binding SID.  The encoding of
   the Binding SID within the redirect-to-indirection-id extended
   community is specified in section 4.

   Requirements:

   For redirect to path engineered tunnels it is required that the
   engineered
   tunnel MUST be active operational and allow packets to be
   unidirectional exchanged steered over the
   engineered path between tunnel head- and tail-end.

   Example: Indirection-ID community types to be used:

   o  0 (localised ID): When the intent is to use a localised policy-based steer traffic
      using Indirection.  The engineered path is configured through out-
      of-band procedures and uses the 32-bit Indirection-id table as local
      anchor point on the local flowspec client.  This requires out-
      of-band configuration of the indirection-id table.

   o  6  2 or 3 (Binding Segment ID's): This type can be used when the goal
      is to use MPLS based Segment Routing towards an out-of-band
      configured explicite path.

   o  5 (Tunnel ID): When the intent is to use policy-based steer traffic
      using a Segment
      Routing based global tunnel-id.  The engineered path is configured
      through out-of-band procedures and uses the 32-bit Indirection-id table
      as global anchor point on the local flowspec client.  This
      requires out-of-band configuration of the Binding Segment IDs.

3.3.  Redirection to complex dynamically constructed tunnels

   Description:

   A third use-case describes the application and redirection towards
   complex dynamically constructed tunnels.  For this use-case a BGP
   flowspec controller injects a single flowspec route with two 'redirect-to-
   indirection-id' unique
   'redirect-to-indirection-id' communities attached, each community
   tagged with a different
   Table-ID (TID). Sequence-ID (S-ID).  A flowspec client may
   use the Table-ID (TID) Sequence-ID (S-ID) to sequence the flowspec redirect
   information.  A common use-case scenario would for example be the
   dynamic construction of Segment Routing Central Egress Path
   Engineered tunnel [4] or next-next-hop tunnels.

   Segment Routing Example:

   i.e. a classic Segment Routing example using complex tunnels is found
   in DDoS mitigation and traffic offload.  Suspicious traffic (e.g.

   dirty traffic flows) may be steered policy-based routed into a purpose built
   Segment Routing Central Egress Path Engineered tunnel [4].  For this
   complex dynamic redirect tunnel construction, a first redirect-to-indirection-id redirect-to-
   indirection-id (i.e.  TID=0)
   is  S-ID=0) may be used to redirect traffic into a
   tunnel towards a particlar particular egress router, while a second redirect-to-indirection-id redirect-
   to-indirection-id (i.e.  TID=1)  S-ID=1) is used to steer traffic beyond the
   particular egress router towards a pre-identified interface/peer.

   For this DDoS use-case, in its simplest embodiment, the flowspec
   client must dynamically append 2 MPLS Segment Routing labels.  A
   first MPLS Segment Routing label (the outer label) to steer the
   packet to the egress node (and hence use a shortest path tunnel),
   while a second MPLS label (matching redirect-to-indirection-id with
   TID=1), the inner label, to steer on the egress router the original
   packet to a pre-defined interface/peer.  The basic
   From data-plane perspective, the principles are documented by [4]. [4] are
   valid for this use case scenario.

   Requirements:

   To achieve redirection towards complex dynamically constructed
   tunnels, for each flowspec route, multiple indirection-ids, each
   using a unique Tunnel ID various indirection-id communities are pushed imposed upon a given the
   flowspec policy
   rule.  It route and are sequenced using the Sequence ID (S-ID).  For
   redirect to complex dynamic engineered tunnels it is required that there is synchronisation established
   between
   the data-plane and control-plane of all relevant devices
   involved.  Each complex dynamically constructed tunnel MUST be operational and allow packets to be unidirectional exchanged steered over
   the engineered path between
   tunnel head- and tail-end before it can be used to redirect traffic. tunnel head- and tail-end.

   Example: Indirection-ID community types to be used:

   o  0 (localised ID) with TID: S-ID: When the intent is to use construct a localised
      Indirection-id table,
      dynamic engineered tunnel, then the TID (Table-ID) a sequence of localised
      indirection-ids may be used.  The Sequence ID (S-ID) MUST be used
      to sequence multiple redirect-to-indirection-id actions to
      construct a more complex path engineered tunnel.  The order construction
      of sequencing
      the redirection information MUST be identified by using the TID
      field.

4.  Redirect to localised indirection-id table is done out-of-band and is
      outside scope of this document.

4.  redirect-to-indirection-id Community

   This document defines a new BGP extended community known as a
   Redirect-to-indirection-id extended community.  This extended
   community is a new transitive extended community with the Type and
   the Sub-Type field to be assigned by IANA.  The format of this
   extended community is show in Figure 1.

      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Type          | Sub-Type      | Flags(1 octet)| Indirection ID|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Generalized indirection_id                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 1

   The meaning of the extended community fields are as follows:

   Type: 1 octet to be assigned by IANA.

   Sub-Type: 1 octet to be assigned by IANA.

   Flags: 1 octet field.  Following Flags are defined.

                              0             1
                              0 1 2 3 4 5 6 7
                             +-+-+-+-+-+-+-+-+
                             | RES |  TID S-ID  |C|
                             +-+-+-+-+-+-+-+-+

                                 Figure 2

   The least-significant Flag bit is defined as the 'C' (or copy) bit.
   When the 'C' bit is set the redirection applies to copies of the
   matching packets and not to the original traffic stream.

   The 'TID' 'S-ID' field identifies a 4 bit Table-id Sequence ID field.  This field is
   used to provide the a flowspec client an indication how and where to
   sequence the received indirection-ids to redirecting traffic.  TID indirection-ids.  The Sequence ID value 0
   indicates that Table-id Sequence ID field is NOT set and SHOULD be ignored.  A
   single flowspec rule MUST NOT have more as one indirection-id per
   S-ID.  On a flowspec client the indirection-id with lowest TID S-ID MUST
   be processed imposed first for a any given flowspec route. entry.

   All bits other than the 'C' and 'TID' 'S-ID' bits MUST be set to 0 by the
   originating BGP speaker and ignored by receiving BGP speakers.

   Indirection ID: 1 octet value.  This draft defines following
   indirection_id
   indirection-id Types:

      0 - Localised ID (The flowspec client uses the received
      indirection-id to lookup the redirection forwarding information in within the
      localised indirection-id table.  The allocation and programming of
      the localised indirection-id table.) table is outside scope of the
      document)

      1 - Node ID (The flowspec client uses the received with SID/index in MPLS-based Segment Routing (This
      means indirection-id is mapped to an MPLS label using the index as
      a Segment Routing global offset in the SID/label space)
      2 - Node ID with SID/label in MPLS-based Segment Routing (This
      means indirection-id is mapped to redirect traffic towards)

      6 an MPLS label using the label as
      global label)

      3 - Binding Segment ID (The flowspec client uses the received with SID/index in MPLS-based Segment
      Routing (This means indirection-id is mapped to an MPLS binding
      label using the index as a Segment Routing global offset in the SID/label space)
      [I-D.draft-ietf-spring-segment-routing] [6]

      4 - Binding Segment ID with SID/label in MPLS-based Segment
      Routing (This means indirection-id is mapped to redirect
      traffic towards) an MPLS binding
      label using the index as a global offset in the SID/label space)
      [I-D.draft-ietf-spring-segment-routing] [6]

      5 - Tunnel ID (Tunnel ID is a global value in a network single
      administrative domain identifying tunnel information.  The
      allocation of the Tunnel ID is out of the scope of the document.)

5.  Redirect using localised indirection-id mapping table

   When a BGP flowspec client receives a flowspec policy route with a
   redirect-to-indirection-id extended community attached and the route
   represents the best BGP path, it will install a flowspec traffic
   filtering policy-based
   forwarding rule matching the IP tupples described by the flowpsec NLRI
   field and consequently redirects the flow (C=0) or copies the flow
   (C=1) using the information identified by the 'redirect-to-
   indirection-id' community.

6.  Validation Procedures

   The validation check described in RFC5575 [2] and revised in [3]
   SHOULD be applied by default to by a flowspec client, for received flow-spec
   flowspec policy routes with containing a
   'redirect to indirection-id' 'redirect-to-indirection-id'
   extended community.  This means that a flow-spec route with a
   destination prefix subcomponent SHOULD NOT be accepted from an EBGP
   peer unless that peer also advertised the best path for the matching
   unicast route.

   While it MUST NOT happen, and is seen as invallid invalid combination, it is
   possible from a semenatics semantics perspective to have multiple clashing
   redirect actions defined within a single flowspec rule.  For best and
   consistant RFC5575 flowspec redirect behavior with legacy implementations, the redirect functionality as
   documented by RFC5575 MUST not NOT be broken, and hence when a clash
   occurs, then RFC5575 based redirect SHOULD MUST take priority.
   Additionally, if the 'redirect to indirection-id' 'redirect-to-indirection-id' does not result in
   a valid redirection, then the flowspec rule must MUST be processed as if
   the 'redirect to indirection-id' 'redirect-to-indirection-id' community was not attached to the
   flowspec route and MUST provide an indication within the BGP routing
   table that the respective 'redirect to indirection-id' 'redirect-to-indirection-id' resulted in an
   invalid redirection action.

7.  Security Considerations

   A system using 'redirect-to-indirection-id' extended community can
   cause during the redirect mitigation of a DDoS attack result in
   overflow of traffic received by the mitigation infrastructure.

8.  Acknowledgements

   This document received valuable comments and input from IDR working
   group including Adam Simpson, Mustapha Aissaoui, Jan Mertens, Robert
   Raszuk, Jeff Haas, Susan Hares and Lucy Yong.

9.  Contributor Addresses

   Below is a list of other contributing authors in alphabetical order:

   Arjun Sreekantiah
   Cisco Systems
   170 W. Tasman Drive
   San Jose, CA  95134
   USA

   Email: asreekan@cisco.com

   Nan Wu
   Huawei Technologies
   Huawei Bld., No. 156 Beiquing Rd
   Beijing  100095
   China

   Email: eric.wu@huawei.com

   Shunwan Zhuang
   Huawei Technologies
   Huawei Bld., No. 156 Beiquing Rd
   Beijing  100095
   China

   Email: zhuangshunwan@huawei.com

   Wim Henderickx
   Nokia
   Antwerp
   BE

   Email: wim.henderickx@nokia.com

                                 Figure 3

10.  IANA Considerations

   This document requests a new type and sub-type for the Redirect to redirect-to-
   indirection-id Extended community from the "Transitive Extended
   community" registry.  The Type name shall be "Redirect to "Redirect-to-
   indirection-id Extended Community" and the Sub-type name shall be
   'Flow-spec Redirect to 32-bit Path-id'.

   In addition, this document requests IANA to create a new registry for
   Redirect to indirection-id
   redirect-to-indirection-id Extended Community INDIRECTION-IDs as
   follows:

   Under "Transitive Extended Community:"

   Registry: "Redirect Extended Community indirection_id"

   Reference: [RFC-To-Be]

   Registration Procedure(s): First Come, First Served

   Registry: "Redirect Extended Community indirection_id"

           Value    Code                              Reference

           0        Localised ID                      [RFC-To-Be]
           1        Node ID                           [RFC-To-Be]
           6        Tunnel ID (Tunnel
     2        Binding ID )                        [RFC-To-Be]
           3        Tunnel ID                         [RFC-To-Be]

                                 Figure 4

11.  References

11.1.  Normative References

   [1]        Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997,
              <http://xml.resource.org/public/rfc/html/rfc2119.html>.

   [2]        Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J.,
              and D. McPherson, "Dissemination of Flow Specification
              Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009,
              <https://www.rfc-editor.org/info/rfc5575>.

11.2.  Informative References

   [3]        Uttaro, J., Filsfils, C., Alcaide, J., and P. Mohapatra,
              "Revised Validation Procedure for BGP Flow
              Specifications", January 2014.

   [4]        Filsfils, C., Previdi, S., Aries, E., Ginsburg, D., and D.
              Afanasiev, "Segment Routing Centralized Egress Peer
              Engineering", October 2015.

   [5]        Sreekantiah, A., Filsfils, C., Previdi, S., Sivabalan, S.,
              Mattes, P., and S. Lin, "Segment Routing Traffic
              Engineering Policy using BGP", October 2015.

   [6]        Filsfils, C., Previdi, S., Decraene, B., Litkowski, S.,
              Shakir, R., Bashandy, A., Horneffer, M., Henderickx, W.,
              Tantsura, J., Crabbe, E., Milojevic, I., and S. Ytti,
              "Segment Routing Architecture", December 2015.

   [7]        Sivabalan, S., Medved, M., Filsfils, C., Litkowski, S.,
              Raszuk, R., Bashandy, A., Lopez, V., Tantsura, J.,
              Henderickx, W., Hardwick, J., Milojevic, I., and S. Ytti,
              "PCEP Extensions for Segment Routing", December 2015.

Authors' Addresses

   Gunter Van de Velde (editor)
   Nokia
   Antwerp
   BE

   Email: gunter.van_de_velde@nokia.com

   Keyur Patel
   Arrcus
   USA

   Email: keyur@arrcus.com

   Zhenbin Li
   Huawei Technologies
   Huawei Bld., No. 156 Beiquing Rd
   Beijing  100095
   China

   Email: lizhenbin@huawei.com