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SPRING                                                  C. Filsfils, Ed.
Internet-Draft                                         P. Camarillo, Ed.
Intended status: Standards Track                     Cisco Systems, Inc.
Expires: August 28, 2020                                          D. Cai
                                                                 Alibaba
                                                                D. Voyer
                                                             Bell Canada
                                                               I. Meilik
                                                                Broadcom
                                                                K. Patel
                                                            Arrcus, Inc.
                                                           W. Henderickx
                                                                   Nokia
                                                         P. Jonnalagadda
                                                       Barefoot Networks
                                                               D. Melman
                                                                 Marvell
                                                       February 25, 2020


          Network Programming extension: SRv6 uSID instruction
          draft-filsfils-spring-net-pgm-extension-srv6-usid-04

Abstract

   The SRv6 "micro segment" (SRv6 uSID or uSID for short) instruction is
   a straightforward extension of the SRv6 Network Programming model:

   o  The SRv6 Control Plane is leveraged without any change

   o  The SRH dataplane encapsulation is leveraged without any change

   o  Any SID in the SID list can carry micro segments

   This enables:

   o  ultra-scale (e.g. multi-domain 5G deployments)

   o  minimum MTU overhead

   o  installed-base reuse

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




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   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 August 28, 2020.

Copyright Notice

   Copyright (c) 2020 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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Notation for human readability  . . . . . . . . . . . . .   4
   3.  SRv6 behaviors associated with a uSID . . . . . . . . . . . .   5
     3.1.  uN  . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Routing . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Benefits  . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Running code  . . . . . . . . . . . . . . . . . . . . . . . .   7
   7.  Security  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   8.  Work in progress  . . . . . . . . . . . . . . . . . . . . . .   8
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8



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   10. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   8
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  12
     11.2.  Informative References . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

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 extension fully leverages the SRv6 network programming solution:

   o  The SRv6 Control Plane is leveraged without any change

   o  The SRH dataplane encapsulation is leveraged without any change

   o  Any SID in the SID list can carry micro segments

   This enables:

   o  ultra-scale (e.g. multi-domain 5G deployments)

   o  minimum MTU overhead

   o  installed-base reuse



















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2.  Terminology

   The SRv6 Network Programming and SRH terminology is leveraged and
   extended with the following terms:

   +----------+--------------------------------------------------------+
   | Term     | Definition                                             |
   +----------+--------------------------------------------------------+
   | uSID     | A block of uSID's. It can be any IPv6 prefix available |
   | block    | to the provider. In this note we will assume a /32     |
   |          | sub-allocated from a public block                      |
   |          | [I-D.matsushima-spring-srv6-deployment-status]. Other  |
   |          | block length could be used.                            |
   +----------+--------------------------------------------------------+
   | uSID     | In this document a 16-bit ID. A different uSID length  |
   |          | may be used.                                           |
   +----------+--------------------------------------------------------+
   | Active   | First uSID after the uSID block.                       |
   | uSID     |                                                        |
   +----------+--------------------------------------------------------+
   | Next     | Next uSID after the Active uSID.                       |
   | uSID     |                                                        |
   +----------+--------------------------------------------------------+
   | Last     | From left to right, the last uSID before the first     |
   | uSID     | End-of-Carrier uSID.                                   |
   +----------+--------------------------------------------------------+
   | End-of-  | Reserved uSID used to mark the end of a uSID carrier.  |
   | 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.           |
   +----------+--------------------------------------------------------+
   | uSID     | A 128bit SRv6 SID of format <uSID-Block><Active-uSID>  |
   | carrier  | <Next-uSID>...<Last-uSID><End-of-Carrier>...<End-of-   |
   |          | Carrier>.  A uSID carrier can be encoded in the        |
   |          | Destination Address of an IPv6 header or at any        |
   |          | position in the Segment List of an SRH.                |
   +----------+--------------------------------------------------------+

2.1.  Notation for human readability

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

      2001:db8::/32 is the uSID block used in the SR domain

      0N00: uN behavior bound to node N




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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 80b argument, "Arg", which contains the next
   uSIDs in the uSID carrier.

   When N receives a packet whose IPv6 DA matches a local uN SID, N
   does:

   1.   IF DA[48..63] != 0                                       ;; Ref1
   2.      Copy DA[48..127] into DA[32..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.

4.  Routing

   If Node 1 is configured with a uN SID 2001:db8:0100::/48 then the
   operator must ensure that Node 1 advertises 2001:db8:0100::/48 in
   routing.
















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5.  Benefits

   o  Leverages SRv6 Network Programming with NO change

      *  SRv6 uSID is an instruction of the SRv6 network programming
         model

   o  Leverages SRv6 dataplane (SRH) with NO change

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

   o  Leverages SRv6 Control-Plane with NO change

   o  Ultra-Scale

      *  6 uSID' per uSID carrier

      *  18 source routing waypoints in solely 40bytes of overhead

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

         +  6 uSID's in DA and 12 in SRH

   o  Lowest MTU overhead

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

   o  Scalable number of globally unique nodes in the domain

      *  16-bit uSID: 65k uSIDs per domain block

      *  32-bit uSID: 4.3M uSIDs per domain block

   o  Proven Hardware-friendliness

      *  Leverages mature hardware capabilities (shift, DA longest
         match)

      *  Avoids any extra lookup in indexed mapping table

      *  Demonstrated by the number of linerate interoperable hardware
         implementations at the first Interop report in February 2020,
         less than 9 months after the first public version of this
         document.

      *  Public operator report of leverage of installed base



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      *  A micro-program which requires less than 6 uSID's only requires
         legacy IPinIP encapsulation behavior


   o  Scalable Control-Plane

      *  No indexed mapping table is required

      *  Summarization at area/domain boundary provides massive scaling
         advantage

      *  No routing extension is required: a simple prefix advertisement
         suffices

   o  Seamless Deployment

      *  A uSID may be used as a SID: i.e. the carrier holds a single
         uSID

      *  The inner structure of an SR Policy can stay opaque to the
         source: i.e. a carrier with uSID's is just seen as a SID by the
         policy headend

   o  Security

      *  Leverages SRv6's native SR domain security

   o  Large-Scale DC

      *  SID's may be used to address applications on hosts (scale in
         2^128)

      *  Hardware friendliness of uSID's may be used to specify billions
         of waypoints in cost/power-optimized DC fabric

6.  Running code

   The hardware and software platforms listed below have demonstrated
   support for the uN instruction defined in this document.

   Further on, all these implementations have participated in a joint
   interoperability testing.

   Hardware implementations (in alphabetical order):

   o  Arrcus ArcOS (based on Broadcom Jericho2)

   o  Barefoot Tofino NPU



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   o  Cisco 8000 Series Routers (based on Cisco Silicon One Q100)

   o  Cisco ASR9000 platform (with 3rd gen Tomahawk and 4th gen
      Lightspeed line-cards)

   o  Cisco NCS5500 platform (based on Broadcom Jericho/Jericho+)

   o  Marvell Prestera Falcon CX 8500

   Software open-source implementations (in alphabetical order):

   o  FD.io VPP

   o  Linux Kernel

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.  Work in progress

   Future version of this document will include other uSID behaviors
   related to TE, VPN and service programming.

9.  Acknowledgements

   The authors would like to acknowledge Francois Clad, Peter Psenak,
   Ketan Talaulikar, Jakub Horn, 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.

10.  Contributors

   Jisu Bhattacharyaa
   Cisco Systems, Inc.
   United States of America

   Email: jisu@cisco.com



   Kamran Raza
   Cisco Systems, Inc.



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   Canada

   Email: skraza@cisco.com



   John Bettink
   Cisco Systems, Inc.
   United States of America

   Email: jbettink@cisco.com



   Tomonobu Niwa
   KDDI
   Japan

   Email: to-niwa@kddi.com



   Luay Jalil
   Verizon
   United States of America

   Email: luay.jalil@one.verizon.com



   Zhichun Jiang
   Tencent
   China

   Email: zcjiang@tencent.com



   Ahmed Shawky
   Saudi Telecom Company
   Saudi Arabia

   Email: ashawky@stc.com.sa



   Nic Leymann
   Deutsche Telekom



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   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



   Jim Uttaro
   AT&T
   United States of America

   Email: ju1738@att.com



   Ning So
   Reliance
   United States of America

   Email: Ning.So@ril.com



   Michael Fiumano
   Sprint



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   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



   Takuya Miyasaka
   KDDI
   Japan

   Email: ta-miyasaka@kddi.com



   Kentaro Ebisawa
   Toyota Motor Corporation



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   Japan

   Email: ebisawa@toyota-tokyo.tech



   Yukito Ueno
   NTT Communications Corporation
   Japan

   Email: yukito.ueno@ntt.com



11.  References

11.1.  Normative References

   [I-D.ietf-6man-segment-routing-header]
              Filsfils, C., Dukes, D., Previdi, S., Leddy, J.,
              Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
              (SRH)", draft-ietf-6man-segment-routing-header-26 (work in
              progress), October 2019.

   [I-D.ietf-spring-srv6-network-programming]
              Filsfils, C., Camarillo, P., Leddy, J., Voyer, D.,
              Matsushima, S., and Z. Li, "SRv6 Network Programming",
              draft-ietf-spring-srv6-network-programming-10 (work in
              progress), February 2020.

   [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>.

11.2.  Informative References

   [I-D.matsushima-spring-srv6-deployment-status]
              Matsushima, S., Filsfils, C., Ali, Z., and Z. Li, "SRv6
              Implementation and Deployment Status", draft-matsushima-
              spring-srv6-deployment-status-05 (work in progress),
              January 2020.





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Authors' Addresses

   Clarence Filsfils (editor)
   Cisco Systems, Inc.
   Belgium

   Email: cf@cisco.com


   Pablo Camarillo (editor)
   Cisco Systems, Inc.
   Spain

   Email: pcamaril@cisco.com


   Dennis Cai
   Alibaba
   China

   Email: d.cai@alibaba-inc.com


   Daniel Voyer
   Bell Canada
   Canada

   Email: daniel.voyer@bell.ca


   Israel Meilik
   Broadcom
   Israel

   Email: israel.meilik@broadcom.com


   Keyur Patel
   Arrcus, Inc.
   United States of America

   Email: keyur@arrcus.com









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   Wim Henderickx
   Nokia
   Belgium

   Email: wim.henderickx@nokia.com


   Prem Jonnalagadda
   Barefoot Networks
   United States of America

   Email: prem@barefootnetworks.com


   David Melman
   Marvell
   Israel

   Email: davidme@marvell.com
































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