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SPRING                                                  C. Filsfils, Ed.
Internet-Draft                                       Cisco Systems, Inc.
Intended status: Standards Track                                  D. Cai
Expires: January 9, 2020                                         Alibaba
                                                                Z. Jiang
                                                                 Tencent
                                                                D. Voyer
                                                             Bell Canada
                                                               A. Shawky
                                                   Saudi Telecom Company
                                                              N. Leymann
                                                        Deutsche Telekom
                                                            D. Steinberg
                                           Lapishills Consulting Limited
                                                                S. Zandi
                                                                G. Dawra
                                                                LinkedIn
                                                               I. Meilik
                                                                Broadcom
                                                               J. Uttaro
                                                                    AT&T
                                                                L. Jalil
                                                                 Verizon
                                                                   N. So
                                                                Reliance
                                                              M. Fiumano
                                                                  Sprint
                                                              M. Khaddam
                                                                     Cox
                                                                   J. Ma
                                                            China Unicom
                                                           S. Matsushima
                                                                Softbank
                                                             F. Ferguson
                                                             CenturyLink
                                                             T. Miyasaka
                                                                    KDDI
                                                              K. Ebisawa
                                                Toyota Motor Corporation
                                                                 Y. Ueno
                                          NTT Communications Corporation
                                                           W. Henderickx
                                                                   Nokia
                                                         P. Jonnalagadda
                                                       Barefoot Networks
                                                         J. Bhattacharya
                                                                 K. Raza
                                                       P. Camarillo, Ed.
                                                     Cisco Systems, Inc.
                                                            July 8, 2019

          Network Programming extension: SRv6 uSID instruction
          draft-filsfils-spring-net-pgm-extension-srv6-usid-00

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Internet-DraNetwork Programming extension: SRv6 uSID instruct  July 2019


Abstract

   The SRv6 "micro segment" (SRv6 uSID or uSID for short) instruction is
   defined and illustrated.

   It is a straightforward extension to the SRv6 Network Programming
   model and its SRH encapsulation.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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 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 January 9, 2020.

Copyright Notice

   Copyright (c) 2019 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
   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.




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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Notation for human readability  . . . . . . . . . . . . .   5
   3.  SRv6 behaviors associated with a uSID . . . . . . . . . . . .   5
     3.1.  uN  . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Routing . . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  Illustration  . . . . . . . . . . . . . . . . . . . . . . . .   6
     5.1.  Reference diagram . . . . . . . . . . . . . . . . . . . .   6
     5.2.  SRv6 overlay with underlay optimization . . . . . . . . .   6
   6.  Benefits  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Security  . . . . . . . . . . . . . . . . . . . . . . . . . .   9
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   9.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   9
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     10.2.  Informative References . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

























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1.  Introduction

   SRv6 Network Programming [I-D.ietf-spring-srv6-network-programming]
   defines a mechanism to build a network program with topological and
   service segments.  It leverages the SRH
   [I-D.ietf-6man-segment-routing-header] to encode a network program
   together with optional metadata shared among the different SIDs.

   This draft extends SRv6 Network Programming with a new type of SRv6
   SID behavior: SRv6 uN.  This is combined with the rest of
   instructions of the network program and the SRH encapsulation to
   build programs in a scalable and efficient way.

2.  Terminology

   The SRv6 Network Programming
   [I-D.ietf-spring-srv6-network-programming] and SRH
   [I-D.ietf-6man-segment-routing-header] terminology is leveraged and
   extended with the following terms:

   uSID carrier: a 128bit SRv6 SID of format <uSID-Block><Active-
   uSID><Next-uSID>...<Last-uSID><End-of-Carrier>...<End-of-Carrier>.

   uSID block: A block of uSID's

      It can be any IPv6 prefix allocated to the provider (e.g. /40 or
      /48), or it can be any block generally available for private use.
      An SR domain may have multiple uSID blocks.

      In this document we leverage FC00::/8 block reserved for private
      use as ULA space (RFC4193).  Throughout this document we use
      FC00::/16 as the illustrated uSID block.  ULA space allows for up
      to 256 uSID blocks in FC00::/8.

   uSID: in this document a 16-bit ID.  A different length may be used.

   Active uSID: first uSID after the uSID block

   Next uSID: next uSID after the Active uSID

   Last uSID: from left to right, the last uSID before the first End-of-
   Carrier uSID

   End-of-Carrier: reserved ID used to mark the end of a uSID carrier.
   The value 0000 is selected as End-of-Carrier.  All of the empty uSID
   carrier positions must be filled with the End-of-Carrier ID.  Hence,
   the End-of-Carrier can be present more than once in a uSID carrier.




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   Parent (node): the node at which an uSID is instantiated.  The uSIDs
   are instantiated on a per-parent node basis.

   Behavior of an uSID: the SRv6 function associated with a given ID.
   Section 3 defines them.

2.1.  Notation for human readability

   For human readability, the example in this document follow this
   notation:

      FC00::/16 is the uSID block used in the SR domain

      0N00: uN behavior bound to node N

3.  SRv6 behaviors associated with a uSID

   The SRv6 SRH encapsulation and its network programming model are
   extended with the following functions:

3.1.  uN

   The uN behavior is a variant of the endpoint behavior.

   This behavior takes a 96b argument, "Arg", which contains the next
   uSIDs in the uSID carrier.

   When N receives a packet whose IPv6 DA is S and S is a local uN SID,
   N does:

   1.   IF DA[32..47] != 0                                       ;; Ref1
   2.      Copy DA[32..127] into DA[16..111]
   3.      Set DA[112..127] to 0x0000
   4.      Forward the packet to the new DA
   5.   ELSE
   6.      Execute the End pseudocode                            ;; Ref2

   Ref 1: DA[X..Y] refers to the bits from position X to Y (included) in
   the IPv6 Destination Address of the received packet.  The bit 0 is
   the MSB, while the bit 127 is the LSB.

   Ref 2: This refers to the End behavior as defined in Section 4.1 of
   [I-D.ietf-spring-srv6-network-programming].  The End behavior may be
   combined with the PSP, USP and USD flavours.







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4.  Routing

   If N is configured with a uN SID FC00:0N00::/32 then the operator
   must ensure that N advertises FC00:0N00::/32 in routing.

5.  Illustration

   This section extends the illustrations for SRv6 Network Programming
   [I-D.filsfils-spring-srv6-net-pgm-illustration] to cover uSID.  The
   reference topology is the same with the addition of link 6-8.

5.1.  Reference diagram

   Nodes 1 to 8 are considered within the network domain.

   Nodes X and Y are outside the domain.

   Nodes 1 and 8 act as PE respectively to nodes X and Y.

   All the links within the domain have the same IGP metric.  The IGP-
   metric shortest-path from 1 to 8 is 1-2-7-8 while the latency-metric
   shortest-path from 1 to 8 is 1-2-3-4-5-6-7-8.

                                3------4---5
                                |       \ /
                                |        6
                                |       / \
                           1--- 2------7---8
                          /                 \
                         X                   Y
                    Tenant100            Tenant100 with
                                           IPv4 20/8

                       Figure 1: Reference topology

5.2.  SRv6 overlay with underlay optimization

   Let us illustrate a low-latency SR-L3VPN service delivered to a
   packet (X,Y).

   PE 1 encapsulates (X, Y) in an outer IPv6 header with DA =
   FC00:0300:0500:0700:: and SRH (B:8:D0::; SL=1; NH=4).  Leveraging the
   illustration conventions from SRv6 network programming, the following
   resulting packet leaves node 1 in the direction of node 3:

      (A1::, FC00:0300:0500:0700::)(B:8:D0::; SL=1; NH=4)(X, Y)





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   FC00:0300:0500:0700:: is a uSID carrier encoding a source routed
   stateless path via node 3 then 5 then 7.

   B:8:D0:: is an End.DT4 SID instantiated at node 8.

   1 sends this packet to 2, as 2 is on the shortest-path to
   FC00:0300::/32 advertised by 3.

   When 2 receives the packet, 2 performs a regular IPv6 FIB lookup.  It
   finds a FIB entry for FC00:0300::/32 and forwards along the shortest
   path to 3.

   When 3 receives the packet, 3 matches FC00:0300::/32 in its "My SID
   Table" and executes the uN behavior.  The updated DA becomes
   FC00:0500:0700::. Node 3 then performs a lookup on the updated DA and
   forwards the packet to 5 along the shortest path to FC00:0500::/32.

   The following packet leaves node 3:

      (A1::, FC00:0500:0700::)(B:8:D0::; SL=1; NH=4)(X, Y)

   4 forwards along the shortest path to FC00:0500::/32.

   When 5 receives the packet, 5 matches FC00:0500::/32 in its "My SID
   Table" and executes the uN behavior.  The updated DA becomes
   FC00:0700::. 5 performs a lookup on the updated DA and forwards the
   packet to 7 along the shortest path to FC00:0700::/32.

   The following packet leaves node 5:

      (A1::, FC00:0700::)(B:8:D0::; SL=1; NH=4)(X, Y)

   6 forwards along the shortest path to FC00:0700::/32.

   When 7 receives the packet, 7 matches FC00:0700::/32 in its "My SID
   Table" and finds the bound function uN.  As a result, Node 7 executes
   the "End with PSP and USD support" pseudocode, decrementing the SL
   value in the SRH, and updating the DA with the next SID B:8:D0::.
   Since the SL value is zero the SRH is removed.  Node 7 performs a
   lookup on the updated DA and forwards along the shortest path.

   The following packet leaves node 7:

      (A1::, B:8:D0::)(X, Y)

   8 receives it, performs the End.DT4 function and sends the IP packet
   (X, Y) towards its VPN destination.




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   This example illustrates the benefits highlighted in the next
   section.

6.  Benefits

      Perfect integration with SRv6 Network Programming

         SRv6 uSID is an instruction of the SRv6 network programming
         model

      Perfect integration with SRH

         Any SID in DA or SRH can be an SRv6 uSID carrier

      Scalable SR Policy

         7 uSID' per uSID carrier

         21 source routing waypoints in solely 40bytes of overhead

            T.Encaps.Red with an SRH of 40 bytes (8 fixed + 2 * 16
            bytes)

            7 uSID's in DA and 14 in SRH

      Efficient MTU overhead

         In apple to apple comparison, the SRv6 solution outperforms any
         alternative (VxLAN with SR-MPLS, CRH).

      Scalable number of globally unique nodes in the domain

         16-bit uSID: 65k uSIDs per domain block (*256 solely using
         FC/8)

         32-bit uSID: 4.3M uSIDs per domain block (*256 solely using
         FC/8)

      Hardware-friendly:

         Leverages mature hardware capabilities (shift)

         Avoids any extra lookup in indexed mapping table

         Demonstrated by Cisco linerate implementation on Jericho1

      Control-Plane friendly




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         No indexed mapping table is required

         No routing extension is required: a simple /32 advertisement
         suffices

7.  Security

   The security rules defined in Section 7 of
   [I-D.ietf-spring-srv6-network-programming], protect intra-domain
   deployments that includes SRv6 uSID.

8.  Acknowledgements

   The authors would like to acknowledge Francois Clad, Peter Psenak,
   Ketan Talaulikar, Swadesh Agrawal, Zafar Ali, Darren Dukes, Kiran
   Sadshiran, Junaid Israr, Lakshmanan Srikanth, Asif Islam, Saleem
   Hafeez, Michael MacKenzie, Sushek Shekar, YuanChao Su, Alexander
   Preusche, Alberto Donzelli, Miya Kohno, David Smith, Ianik Semco,
   Bertrand Duvivier, Frederic Trate, Kris Michielsen, Eyal Dagan, Eli
   Stein, Ofer Iny, Elad Naor, Aviad Behar, Joseph Chin.

9.  Contributors

   Tomonobu Niwa
   KDDI
   Japan

   Email: to-niwa@kddi.com

10.  References

10.1.  Normative References

   [I-D.ietf-6man-segment-routing-header]
              Filsfils, C., Dukes, D., Previdi, S., Leddy, J.,
              Matsushima, S., and d. daniel.voyer@bell.ca, "IPv6 Segment
              Routing Header (SRH)", draft-ietf-6man-segment-routing-
              header-21 (work in progress), June 2019.

   [I-D.ietf-spring-srv6-network-programming]
              Filsfils, C., Camarillo, P., Leddy, J.,
              daniel.voyer@bell.ca, d., Matsushima, S., and Z. Li, "SRv6
              Network Programming", draft-ietf-spring-srv6-network-
              programming-01 (work in progress), July 2019.







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Internet-DraNetwork Programming extension: SRv6 uSID instruct  July 2019


   [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>.

   [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>.

10.2.  Informative References

   [I-D.filsfils-spring-srv6-net-pgm-illustration]
              Filsfils, C., Camarillo, P., Li, Z., Matsushima, S.,
              Decraene, B., Steinberg, D., Lebrun, D., Raszuk, R., and
              J. Leddy, "Illustrations for SRv6 Network Programming",
              draft-filsfils-spring-srv6-net-pgm-illustration-00 (work
              in progress), February 2019.

Authors' Addresses

   Clarence Filsfils (editor)
   Cisco Systems, Inc.
   Belgium

   Email: cf@cisco.com


   Dennis Cai
   Alibaba
   China

   Email: d.cai@alibaba-inc.com


   Zhichun Jiang
   Tencent
   China

   Email: zcjiang@tencent.com


   Daniel Voyer
   Bell Canada
   Canada

   Email: daniel.voyer@bell.ca





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   Ahmed Shawky
   Saudi Telecom Company
   Saudi Arabia

   Email: ashawky@stc.com.sa


   Nic Leymann
   Deutsche Telekom
   Germany

   Email: N.Leymann@telekom.de


   Dirk Steinberg
   Lapishills Consulting Limited
   Cyprus

   Email: dirk@lapishills.com


   Shawn Zandi
   LinkedIn
   United States of America

   Email: szandi@linkedin.com


   Gaurav Dawra
   LinkedIn
   United States of America

   Email: gdawra@linkedin.com


   Israel Meilik
   Broadcom
   Israel

   Email: israel.meilik@broadcom.com


   Jim Uttaro
   AT&T
   United States of America

   Email: ju1738@att.com




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   Luay Jalil
   Verizon
   United States of America

   Email: luay.jalil@one.verizon.com


   Ning So
   Reliance
   United States of America

   Email: Ning.So@ril.com


   Michael Fiumano
   Sprint
   United States of America

   Email: michael.f.fiumano@sprint.com


   Mazen Khaddam
   Cox
   United States of America

   Email: Mazen.Khaddam@cox.com


   Jichun Ma
   China Unicom
   China

   Email: majc16@chinaunicom.cn


   Satoru Matsushima
   Softbank
   Japan

   Email: satoru.matsushima@g.softbank.co.jp


   Francis Ferguson
   CenturyLink
   United States of America

   Email: Francis.Ferguson@centurylink.com




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   Takuya Miyasaka
   KDDI
   Japan

   Email: ta-miyasaka@kddi.com


   Kentaro Ebisawa
   Toyota Motor Corporation
   Japan

   Email: ebisawa@toyota-tokyo.tech


   Yukito Ueno
   NTT Communications Corporation
   Japan

   Email: yukito.ueno@ntt.com


   Wim Henderickx
   Nokia
   Belgium

   Email: wim.henderickx@nokia.com


   Prem Jonnalagadda
   Barefoot Networks
   United States of America

   Email: prem@barefootnetworks.com


   Jisu Bhattacharya
   Cisco Systems, Inc.
   United States of America

   Email: jisu@cisco.com


   Kamran Raza
   Cisco Systems, Inc.
   Canada

   Email: skraza@cisco.com




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   Pablo Camarillo (editor)
   Cisco Systems, Inc.
   Spain

   Email: pcamaril@cisco.com














































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