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Network Working Group                                            X. Geng
Internet-Draft                                                   M. Chen
Intended status: Experimental                                     Huawei
Expires: September 10, 2020                               March 09, 2020


        Redundancy SID and Merging SID for Redundancy Protection
             draft-geng-spring-redundancy-protection-sid-00

Abstract

   Redundancy protection is a method of service protection by sending
   copies of the same packets of one flow over multiple paths, which
   includes packet replication, elimination and ordering.  This document
   defines Redundancy SID and Merging SID to support redundancy
   protection.

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 .

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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   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on September 10, 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



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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology and Conventions . . . . . . . . . . . . . . . . .   2
   3.  Redundancy Protection Introduction  . . . . . . . . . . . . .   3
   4.  Redundancy SID  . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Merging SID . . . . . . . . . . . . . . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   Redundancy protection is a method of providing 1+1 protection by
   sending copies of the same packets of one flow over multiple paths,
   which includes packet replication, elimination and ordering.  This
   document defines Redundancy SID and Merging SID to support redundancy
   protection.

2.  Terminology and Conventions

   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 [RFC2119].

   Redundancy Node: the start point of redundancy protection, which is a
   network device that could implement packet replication.

   Merging Node: the end point of redundancy protection, which is a
   network node that could implement packet elimination and ordering
   (optionally).

   Editor's Note: Similar mechanism is defined as "Service Protection"
   in the [RFC8655].  In this document, we define a new term "Redundancy
   Protection" to distinguish with other service protection method.
   Some of the terms are the similar as [RFC8655].






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3.  Redundancy Protection Introduction

   The figure shows how to provide redundancy protection in an Segment
   Routing Domain.

                |                                         |
                |<---------------SR Domain--------------->|
                |                                         |
                |             +------+T2+----+            |
      +---+    +---+        +-+-+          +-+-+        +---+    +---+
      | E1+----| In|--+T1+--+Red|          |Mer|--+T4+--| Eg+----+ E2|
      +---+    +---+        +-+-+          +-+-+        +---+    +---+
                              +-----+T3+-----+

   The process of redundancy protection is as follows: 1) The flow is
   replicated in Red(Redundancy Node); 2) Tow replicated flows go
   through different paths till Mer (Merging Node); When there is any
   failures happened in one the path, the service continues to deliver
   through the other path without break; 3) The first received packet of
   the flow is transmitted from Mer (Merging Node) to Eg(Egress), and
   the redundant packets are eliminated. 4) Sometimes, the packet will
   arrive out of order because of redundancy protection, the function of
   reordering may be necessary in the Merging Node.

   In this document, we introduces Redundancy SID and Merging SID to
   implement redundancy protection.  The newly defined SIDs apply
   equally to both SR-MPLS and SRv6.

4.  Redundancy SID

   Redundancy SID is a variation of binding SID defined in
   [I-D.ietf-spring-segment-routing-policy]

   Redundancy SID indicates the following operations:

   o  Steering the packet into the corresponding redundancy policy

   o  Packet replication based on the redundancy policy, e.g., the
      number of replication copies

   o  Encapsulate the packet with necessary meta data (e.g., flow
      identification, sequence number) if it is not included in the
      original packet








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5.  Merging SID

   Merging SID indicates the following operations:

   o  Packet elimination: forward the first received packets and
      eliminate the redundant packets.

   o  Packet ordering(optional): reorder the packets if the packet
      arrives out of order

6.  IANA Considerations

   TBD

7.  Security Considerations

   TBD

8.  Acknowledgements

   Thank you for valuable comments from James Guichard and Andrew Mail

9.  Normative References

   [I-D.ietf-spring-segment-routing-policy]
              Filsfils, C., Sivabalan, S., Voyer, D., Bogdanov, A., and
              P. Mattes, "Segment Routing Policy Architecture", draft-
              ietf-spring-segment-routing-policy-06 (work in progress),
              December 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>.

   [RFC8655]  Finn, N., Thubert, P., Varga, B., and J. Farkas,
              "Deterministic Networking Architecture", RFC 8655,
              DOI 10.17487/RFC8655, October 2019,
              <https://www.rfc-editor.org/info/rfc8655>.

Authors' Addresses

   Xuesong Geng
   Huawei

   Email: gengxuesong@huawei.com





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   Mach(Guoyi) Chen
   Huawei

   Email: mach.chen@huawei.com















































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