SPRING                                                  C. Filsfils, Ed.
Internet-Draft                                              F. Clad, Ed.
Intended status: Informational                             K. Talaulikar
Expires: June 2, 2021                                      Cisco Systems
                                                       November 29, 2020


               SR-MPLS Data Plane with IPv6 Control Plane
          draft-filsfils-spring-sr-mpls-ipv6-control-plane-03

Abstract

   This document reminds the existence of the "Segment Routing (SR) MPLS
   data-plane with IPv6 control-plane" solution that is mature from a
   standardization, productization and commercial deployment viewpoint.

Status of This Memo

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   This Internet-Draft will expire on June 2, 2021.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Context . . . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Reference diagram . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Packet processing . . . . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   7.  Informative References  . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   This document reminds the existence of the "Segment Routing (SR) MPLS
   dataplane with IPv6 control-plane".  This solution is mature from a
   standardization, productization and commercial deployment viewpoint.
   Other proposed source routing solutions with MPLS-like label lookup
   or mapping ids should list all their data-plane and control-plane
   differences with respect to this mature solution and should justify
   these differences with genuine benefits not available in the mature
   solution described in this document and others referenced here that
   are published by the SPRING and MPLS WGs.

2.  Context

   This is an existing solution.

   o  Mature IETF standardization

   o  Mature productization

   o  Commercially deployed

   The IETF standardization references are:

   o  Architecture:

      *  Segment Routing [RFC8402]

   o  Data-plane:

      *  Homogenous MPLS deployment: [RFC8660]

      *  Hopping over IP-only parts of network: [RFC8663]

   o  Control-plane:

      *  IS-IS: [RFC8667]



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      *  OSPFv3: [RFC8666]

      *  BGP: [RFC4364]

      *  BGP-LS: [I-D.ietf-idr-bgp-ls-segment-routing-ext]

      *  SR Policy headend: [I-D.ietf-spring-segment-routing-policy]

   o  Service programming: [I-D.ietf-spring-sr-service-programming]

   o  OAM: [RFC8287]

3.  Reference diagram

   +--------------------------------------------------------------+
   | +-------------------+                  +-------------------+ |
   | |                   |                  |                   | |
   | |                 +-+-+              +-+-+                 | |
   | |                 |121|              |231|                 | |
   | |                 +-+-+              +-+-+                 | |
   | | +---+             |                  |             +---+ | |
   | | |PE1|             |                  |             |PE2| | |
   | | +---+           +-+-+              +-+-+           +---+ | |
   | |                 |122|              |232|                 | |
   | |                 +-+-+              +-+-+                 | |
   | |  (MPLS island 1)  |                  |  (MPLS island 2)  | |
   | +-------------------+  (IPv6 network)  +-------------------+ |
   +--------------------------------------------------------------+

                Figure 1: IPv6 network with SR-MPLS islands

   o  Single IGP domain, IPv6 only

      *  PE1 is configured with a loopback IP address 2001:db8::1

      *  PE2 is configured with a loopback IP address 2001:db8::2

      *  Each other node k is configured with a loopback IP address
         2001:db8::k

   o  2 SR-MPLS islands running with an IPv6 control plane

      *  PE1 is configured with a Prefix-SID 16001 associated with
         2001:db8::1

      *  PE2 is configured with a Prefix-SID 16002 associated with
         2001:db8::2




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4.  Packet processing

      +------------------------------------------------------------+
      | +-------------------+                +-------------------+ |
      | |                   |                |                   | |
      | |                 +-+-+            +-+-+                 | |
      | |           +---->+121+----->------+231+-----+           | |
      | |           |     +-+-+            +-+-+     |           | |
      | | +---+     |       |                |       |     +---+ | |
  A +-----+PE1+-----+       |                |       +---->+PE2+-----> B
      | | +---+           +-+-+            +-+-+           +---+ | |
      | |                 |122|            |232|                 | |
      | |                 +-+-+            +-+-+                 | |
      | |  (MPLS island 1)  |                |  (MPLS island 2)  | |
      | +-------------------+ (IPv6 network) +-------------------+ |
      +------------------------------------------------------------+

   +----------+ +----------+ +--------------+ +----------+ +----------+
   | IP4(A,B) | |  16002   | |IP6(          | |  16002   | | IP4(A,B) |
   +----------+ +----------+ |2001:db8::121,| +----------+ +----------+
                |  12345   | |2001:db8::231)| |  12345   |
                +----------+ +--------------+ +----------+
                | IP4(A,B) | |    16002     | | IP4(A,B) |
                +----------+ +--------------+ +----------+
                             |    12345     |
                             +--------------+
                             |   IP4(A,B)   |
                             +--------------+

     Figure 2: Packet processing in IPv6 network with SR-MPLS islands

   o  PE1 receives IPv4 traffic from A and headed to B

   o  PE1 PUSHes the VPN label 12345 and the prefix-SID 16002 of PE2

   o  Traffic is steered in MPLS island 1 according to the top label
      16002

   o  Traffic reaches node 121, whose next-hop towards 16002 is not
      MPLS-enabled

      *  Node 121 has determined(*) that traffic to 16002 should be sent
         over an IPv6 encapsulation to node 231

      *  Node 121 encapsulates the traffic with IPv6 header (Next Header
         137 [RFC4023]) to 2001:db8::231





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   o  Node 231 removes the IPv6 encapsulation, exposes the MPLS label
      16002 and forwards the traffic accordingly

   o  Traffic is steered in MPLS island 2 according to the top label
      16002

   o  (PHP: Penultimate node POPs label 16002 and sends the traffic to
      PE2)

   o  PE2 looks up the exposed VPN label 12345 and forwards the traffic
      accordingly.

   (*) Node 121 determines that node 231 is the closest MPLS- and IPv6-
   pop-capable node on the shortest path to PE2 using a technique
   outside the scope of the document.

5.  IANA Considerations

   None

6.  Acknowledgements

   TBD

7.  Informative References

   [I-D.ietf-idr-bgp-ls-segment-routing-ext]
              Previdi, S., Talaulikar, K., Filsfils, C., Gredler, H.,
              and M. Chen, "BGP Link-State extensions for Segment
              Routing", draft-ietf-idr-bgp-ls-segment-routing-ext-16
              (work in progress), June 2019.

   [I-D.ietf-spring-segment-routing-policy]
              Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
              P. Mattes, "Segment Routing Policy Architecture", draft-
              ietf-spring-segment-routing-policy-09 (work in progress),
              November 2020.

   [I-D.ietf-spring-sr-service-programming]
              Clad, F., Xu, X., Filsfils, C., daniel.bernier@bell.ca,
              d., Li, C., Decraene, B., Ma, S., Yadlapalli, C.,
              Henderickx, W., and S. Salsano, "Service Programming with
              Segment Routing", draft-ietf-spring-sr-service-
              programming-03 (work in progress), September 2020.







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   [RFC4023]  Worster, T., Rekhter, Y., and E. Rosen, Ed.,
              "Encapsulating MPLS in IP or Generic Routing Encapsulation
              (GRE)", RFC 4023, DOI 10.17487/RFC4023, March 2005,
              <https://www.rfc-editor.org/info/rfc4023>.

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
              2006, <https://www.rfc-editor.org/info/rfc4364>.

   [RFC8287]  Kumar, N., Ed., Pignataro, C., Ed., Swallow, G., Akiya,
              N., Kini, S., and M. Chen, "Label Switched Path (LSP)
              Ping/Traceroute for Segment Routing (SR) IGP-Prefix and
              IGP-Adjacency Segment Identifiers (SIDs) with MPLS Data
              Planes", RFC 8287, DOI 10.17487/RFC8287, December 2017,
              <https://www.rfc-editor.org/info/rfc8287>.

   [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>.

   [RFC8660]  Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S.,
              Decraene, B., Litkowski, S., and R. Shakir, "Segment
              Routing with the MPLS Data Plane", RFC 8660,
              DOI 10.17487/RFC8660, December 2019,
              <https://www.rfc-editor.org/info/rfc8660>.

   [RFC8663]  Xu, X., Bryant, S., Farrel, A., Hassan, S., Henderickx,
              W., and Z. Li, "MPLS Segment Routing over IP", RFC 8663,
              DOI 10.17487/RFC8663, December 2019,
              <https://www.rfc-editor.org/info/rfc8663>.

   [RFC8666]  Psenak, P., Ed. and S. Previdi, Ed., "OSPFv3 Extensions
              for Segment Routing", RFC 8666, DOI 10.17487/RFC8666,
              December 2019, <https://www.rfc-editor.org/info/rfc8666>.

   [RFC8667]  Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C.,
              Bashandy, A., Gredler, H., and B. Decraene, "IS-IS
              Extensions for Segment Routing", RFC 8667,
              DOI 10.17487/RFC8667, December 2019,
              <https://www.rfc-editor.org/info/rfc8667>.

Authors' Addresses

   Clarence Filsfils (editor)
   Cisco Systems

   Email: cfilsfil@cisco.com



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   Francois Clad (editor)
   Cisco Systems

   Email: fclad@cisco.com


   Ketan Talaulikar
   Cisco Systems

   Email: ketant@cisco.com









































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