Internet DRAFT - draft-chen-idr-mbinding

draft-chen-idr-mbinding







Network Working Group                                            H. Chen
Internet-Draft                                                 Futurewei
Intended status: Standards Track                             B. Decraene
Expires: 13 May 2024                                              Orange
                                                               G. Mishra
                                                                 Verizon
                                                                  Y. Fan
                                                            Casa Systems
                                                                 A. Wang
                                                           China Telecom
                                                                  X. Liu
                                                               Alef Edge
                                                        10 November 2023


                         BGP for Mirror Binding
                       draft-chen-idr-mbinding-03

Abstract

   BGP is used to distribute a binding to a node.  The binding includes
   a binding SID and a path represented by a list of SIDs.  This
   document describes extensions to BGP for distributing the information
   about the binding to a protecting node.  For an SR path via the node
   with the binding SID, when the node fails, the protecting node such
   as the upstream neighbor on the path uses the information to protect
   the binding SID of the failed node.

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/.






Chen, et al.               Expires 13 May 2024                  [Page 1]

Internet-Draft               Mirror Binding                November 2023


   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 13 May 2024.

Copyright Notice

   Copyright (c) 2023 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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Extensions to BGP . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Procedure for Updating Information  . . . . . . . . . . . . .   5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   [I-D.ietf-idr-segment-routing-te-policy] specifies how BGP may be
   used to distribute a Segment Routing (SR) Policy to a node in a
   network.  An SR Policy may contain a binding, which includes a
   binding SID and a path represented by a list of SIDs.

   After a BGP as a controller distributes the binding to the node, the
   node forwards the packet with the binding SID according to the first
   SID in the list.  It replaces the binding SID in the packet with the
   list of SIDs and forwards the packet using the FIB entry for the top
   SID (i.e., the first SID) in the packet.





Chen, et al.               Expires 13 May 2024                  [Page 2]

Internet-Draft               Mirror Binding                November 2023


   When the node fails, suppose that a protecting node (e.g., the
   upstream neighbor as PLR) of the node has the corresponding binding
   protection information for protecting the binding SID of the node.
   The information includes the binding SID, the list of SIDs and an
   identifier of the node.  After the upstream neighbor as PLR detects
   the failure of the node, for a packet with the node SID of the failed
   node received, it protects the binding SID of the failed node.  It
   replaces the binding SID in the packet with the list of SIDs,
   forwards the packet without going through the failed node towards the
   top SID (i.e., the first SID, assuming it is a node SID for
   simplicity here).  The requirement for distributing the binding
   protection information to a protecting node and how a protecting node
   protect the binding SID of the failed node are out of scope of this
   document and described in
   [I-D.ietf-spring-segment-protection-sr-te-paths] and
   [I-D.hu-spring-segment-routing-proxy-forwarding].  (Note: the second
   reference will be removed after the first one includes enough text
   for protecting binding SIDs of a node).

   This document specifies some procedures and extensions to BGP for
   distributing the information to a protecting node that may protect
   the failed node.

2.  Extensions to BGP

   This section defines a new Binding Protection sub-TLV under a Tunnel
   Encapsulation Attribute TLV of type 15 (i.e., SR Policy TLV).  A
   Tunnel Encapsulation Attribute contains a Tunnel Encapsulation
   Attribute TLV.  The structure containing a Binding Protection sub-TLV
   is shown below.

       Attributes:
           Tunnel Encapsulation Attribute (23)
               Tunnel Type (15): SR Policy TLV
                   Preference sub-TLV
                   Binding SID sub-TLV
                   SRv6 Binding SID sub-TLV
                   Explicit NULL Label Policy (ENLP) sub-TLV
                   Priority sub-TLV
                   Policy Candidate Path Name sub-TLV
                   Policy Name sub-TLV
                   Binding Protection sub-TLV
                   Segment List sub-TLV
                       Weight sub-TLV
                       Segment sub-TLV
                       Segment sub-TLV
                       ...
                   ...



Chen, et al.               Expires 13 May 2024                  [Page 3]

Internet-Draft               Mirror Binding                November 2023


   The format of a Binding Protection sub-TLV is illustrated below.

    0                   1                   2                   3
    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 (TBD1) |    Length     |     Flags     |   RESERVED    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           sub-TLVs                            |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 1: Binding Protection sub-TLV Format

   Type:  Its value (TBD1) is to be assigned by IANA.

   Length:  It is variable.

   Flags:  1 octet of flags.  No flags is defined now.  MUST be set to
      zero by the sender and MUST be ignored by the receiver.

   sub-TLVs:  This field contains the sub-TLV below to indicate the node
      to be protected (i.e., the protected node).

      o  Protected Node ID sub-TLV indicating the ID of the Protected
         Node.

   When an SR Policy (i.e., SR Policy TLV) contains a binding SID and a
   path with a protected node, the SR policy is for distributing the
   binding protection information.  The binding SID is encoded by a
   Binding SID sub-TLV or SRv6 Binding SID sub-TLV, the path is encoded
   by a Segment List Sub-TLV, and the node is encoded by a Binding
   Protection sub-TLV.

   When an SR Policy contains a binding SID and a path without a
   protected node, the SR policy is for replacing the Binding SID with
   the path (i.e., the list of SIDs) when the node receives a packet
   with the Binding SID.

   The format of Protected Node ID sub-TLV is illustrated below.

    0                   1                   2                   3
    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 (1)   |  Length (4)   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Protected Node ID (4 octets)                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




Chen, et al.               Expires 13 May 2024                  [Page 4]

Internet-Draft               Mirror Binding                November 2023


                 Figure 2: Protected Node ID sub-TLV Format

   Type:  Its value (1) indicates the type of Protected Node ID sub-TLV.

   Length:  Its value (4) indicates the length of the value field of the
      sub-TLV is 4.

   Protected Node ID:  4-octet field contains the identifier (ID) of the
      Protected Node.

3.  Procedure for Updating Information

   When a BGP sends a binding to node N for a SR path going through node
   N, the BGP distributes the corresponding binding protection
   information to the possible protecting nodes.  The upstream neighbor
   of node N along the SR path is a protecting node.  If node N is a
   loose hop in the SR path with N's node ID, the upstream node having
   its node SID next to N's node ID in the SR path and the neighbors of
   node N are the possible protecting nodes.

   After sending the binding to node N and distributing the
   corresponding binding protection information to the protecting nodes,
   if BGP removes the binding from node N, it removes the corresponding
   binding protection information from the protecting nodes.  If BGP
   changes the binding in node N, it changes the corresponding binding
   protection information in the protecting nodes.

4.  Security Considerations

   Protocol extensions defined in this document do not affect the BGP
   security other than those as discussed in the Security Considerations
   section of [RFC9012].

5.  IANA Considerations

   This document requests assigning a new sub-TLV in the registry "BGP
   Tunnel Encapsulation Attribute sub-TLVs" as follows:

              +------------+--------------------+-------------+
              | Code Point | Description        | Reference   |
              +------------+--------------------+-------------+
              | TBD1       | Binding Protection |This document|
              +------------+--------------------+-------------+

6.  References

6.1.  Normative References




Chen, et al.               Expires 13 May 2024                  [Page 5]

Internet-Draft               Mirror Binding                November 2023


   [I-D.ietf-spring-segment-protection-sr-te-paths]
              Hegde, S., Bowers, C., Litkowski, S., Xu, X., and F. Xu,
              "Segment Protection for SR-TE Paths", Work in Progress,
              Internet-Draft, draft-ietf-spring-segment-protection-sr-
              te-paths-05, 27 September 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-spring-
              segment-protection-sr-te-paths-05>.

   [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>.

   [RFC9012]  Patel, K., Van de Velde, G., Sangli, S., and J. Scudder,
              "The BGP Tunnel Encapsulation Attribute", RFC 9012,
              DOI 10.17487/RFC9012, April 2021,
              <https://www.rfc-editor.org/info/rfc9012>.

6.2.  Informative References

   [I-D.hu-spring-segment-routing-proxy-forwarding]
              Hu, Z., Chen, H., Yao, J., Bowers, C., Zhu, Y., and Y.
              Liu, "SR-TE Path Midpoint Restoration", Work in Progress,
              Internet-Draft, draft-hu-spring-segment-routing-proxy-
              forwarding-24, 21 August 2023,
              <https://datatracker.ietf.org/doc/html/draft-hu-spring-
              segment-routing-proxy-forwarding-24>.

   [I-D.ietf-idr-segment-routing-te-policy]
              Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P., and
              D. Jain, "Advertising Segment Routing Policies in BGP",
              Work in Progress, Internet-Draft, draft-ietf-idr-segment-
              routing-te-policy-26, 23 October 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-idr-
              segment-routing-te-policy-26>.

Acknowledgments

   The authors would like to thank Andrew Stone, Robert Raszuk, Ketan
   Talaulikar, Donald Eastlake, Zhibo Hu, Haibo Wang, Yao Liu, Changwang
   Lin, Jie Dong and Zhenqiang Li for their comments to this work.

Authors' Addresses




Chen, et al.               Expires 13 May 2024                  [Page 6]

Internet-Draft               Mirror Binding                November 2023


   Huaimo Chen
   Futurewei
   Boston, MA,
   United States of America
   Email: huaimo.chen@futurewei.com


   Bruno Decraene
   Orange
   France
   Email: bruno.decraene@orange.com


   Gyan S. Mishra
   Verizon
   13101 Columbia Pike
   Silver Spring,  MD 20904
   United States of America
   Phone: 301 502-1347
   Email: gyan.s.mishra@verizon.com


   Yanhe Fan
   Casa Systems
   United States of America
   Email: yfan@casa-systems.com


   Aijun Wang
   China Telecom
   Beiqijia Town, Changping District
   Beijing
   102209
   China
   Email: wangaj3@chinatelecom.cn


   Xufeng Liu
   Alef Edge
   United States of America
   Email: xufeng.liu.ietf@gmail.com










Chen, et al.               Expires 13 May 2024                  [Page 7]