Skip to main content

SR Policy for enhanced DetNet
draft-zhang-sr-policy-enhanced-detnet-00

Document Type Active Internet-Draft (individual)
Authors Li Zhang , Xuesong Geng , Zhenbin Li
Last updated 2022-07-11
Stream (None)
Intended RFC status (None)
Formats
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date (None)
Responsible AD (None)
Send notices to (None)
draft-zhang-sr-policy-enhanced-detnet-00
Network Working Group                                           L. Zhang
Internet-Draft                                                   X. Geng
Intended status: Standards Track                                   Z. Li
Expires: 12 January 2023                                          Huawei
                                                            11 July 2022

                     SR Policy for enhanced DetNet
                draft-zhang-sr-policy-enhanced-detnet-00

Abstract

   SR Policy is a set of candidate SR paths consisting of one or more
   segment lists and necessary path attributes.  It enables
   instantiation of an ordered list of segments with a specific intent
   for traffic steering.  DetNet provides the capability to carry
   specified unicast or multicast data flows with extremely low data
   loss rates and bounded end-to-end latency within a network domain.
   This document defines the SR policy enhancement to carry the Bounded
   Latency Information with a candidate path of SR policy.  So that BLI
   behavior can be enabled automatically when the SR Policy is applied.

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 RFC 2119 [RFC2119].

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 12 January 2023.

Zhang, et al.            Expires 12 January 2023                [Page 1]
Internet-Draft              Abbreviated-Title                  July 2022

Copyright Notice

   Copyright (c) 2022 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.  Terminology and Conventions . . . . . . . . . . . . . . . . .   3
     2.1.  Requirement Language  . . . . . . . . . . . . . . . . . .   3
     2.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  BLI Encoding in SR Policy . . . . . . . . . . . . . . . . . .   3
     3.1.  BLI List Sub-TLV  . . . . . . . . . . . . . . . . . . . .   3
     3.2.  Shared BLI sub-TLV  . . . . . . . . . . . . . . . . . . .   5
   4.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Segment Routing Policy is defined
   in[I-D.ietf-spring-segment-routing-policy].  A SR Policy is a set of
   candidate path which consist of one or more segment lists.  The
   headend node instructs the source routing and writes it into package.
   The packets steered into an SR Policy have an ordered list of
   segments associated with that SR Policy written into them.[RFC8655]
   provides the overall architecture for Deterministic Networking
   (DetNet), which provides the capability to carry specified unicast or
   multicast data flows with extremely low data loss rates and bounded
   end-to-end latency within a network domain.  Based on
   this,[I-D.ietf-detnet-bounded-latency] proposed a timing model for
   sources, destinations, and DetNet transit nodes.  Using the model, it
   provides a methodology to compute end-to-end latency and backlog
   bounds for various queuing
   methods.[I-D.yzz-detnet-enhanced-data-plane] enhances the DetNet data
   plane by introducing Bounded Latency Information (BLI) which

Zhang, et al.            Expires 12 January 2023                [Page 2]
Internet-Draft              Abbreviated-Title                  July 2022

   facilitates DetNet transit nodes to guarantee the bounded latency
   transmission in data plane.  Based on
   that,[I-D.geng-spring-sr-enhanced-detnet] defines how to leverage
   Segment Routing (SR) and Segment Routing over IPv6 (SRv6) to
   implement bounded latency.  For An automatic network, the SR Policy
   with Bounded Latency Information can facilitate the bounded latency
   transmission and enable the automation of SR service.

   This document defines the SR policy enhancement to carry the Bounded
   Latency Information with a candidate path of SR policy.  So that BLI
   behavior can be enabled automatically when the SR Policy is applied.

2.  Terminology and Conventions

2.1.  Requirement 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[RFC2119].

2.2.  Terminology

   The abbreviations used in this document are:

   BLI: Bounded Latency Information

   SR: Segment Routing

   SID: Segment Identifier

3.  BLI Encoding in SR Policy

   The BLI is proposed by[I-D.yzz-detnet-enhanced-data-plane] to
   facilitate DetNet transit nodes to guarantee the bounded latency
   transmission in data plane.  In order to specify the bounded latency
   features that the candidate path is associated with, this document
   defines two types of new sub-TLV in the BGP Tunnel Encapsulation
   Attribute for SR Policy[I-D.ietf-spring-segment-routing-policy] for
   different scenarios.

3.1.  BLI List Sub-TLV

   When all of the nodes/adjacencies in the explicit path indicated by
   the segment list request different BLI to guarantee bounded latency,
   a BLI list sub-TLV is defined.

Zhang, et al.            Expires 12 January 2023                [Page 3]
Internet-Draft              Abbreviated-Title                  July 2022

   The BLI list sub-TLV is formatted as follows.

    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            |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        BLI List [m]                           |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             ...                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        BLI List [1]                           |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   Type: to be assigned by IANA.

   Length: 16 bits length value to indicate the length of BLI list in
   octet.

   BLI List [1... m]: 64 bits length BLI structure, representing the nth
   BLI in the BLI list.

   The BLI in the BLI List corresponds to the Segment in the Segment
   List one by one.  The length of the BLI List depends on the num of
   Segment in the Segment List.

   The encoding structure of BGP SR Policy with the BLI list sub-TLV is
   expressed as below:

Zhang, et al.            Expires 12 January 2023                [Page 4]
Internet-Draft              Abbreviated-Title                  July 2022

   SR Policy SAFI NLRI: <Distinguisher, Policy-Color, Endpoint>
               Attributes:
                  Tunnel Encaps Attribute (23)
                     Tunnel Type: SR Policy
                         Binding SID
                         Preference
                         Priority
                         Policy Name
                         Explicit NULL Label Policy (ENLP)
                         Segment List
                             BLI List
                             Weight
                             Segment
                             Segment
                             ...
                             ...

3.2.  Shared BLI sub-TLV

   When all of the nodes/adjacencies in the explicit path indicated by
   the segment list request BLI to guarantee bounded latency with the
   same BLI value, the Shared BLI sub-TLV is defined.

   The Shared BLI sub-TLV is defined as follows:

    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 (TBD2)          |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                            BLI                                |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   Type: to be assigned by IANA.

   Length: 16 bits value indicate the length of BLI.

   BLI: 64 bits value of Bounded Latency Information to guarantee the
   bounded latency, the format of it is defined in section 3.1.

   The encoding structure of BGP SR Policy with the Per-segment BLI sub-
   TLV is expressed as below:

Zhang, et al.            Expires 12 January 2023                [Page 5]
Internet-Draft              Abbreviated-Title                  July 2022

   SR Policy SAFI NLRI: <Distinguisher, Policy-Color, Endpoint>
               Attributes:
                  Tunnel Encaps Attribute (23)
                     Tunnel Type: SR Policy
                         Binding SID
                         Preference
                         Priority
                         Policy Name
                         Explicit NULL Label Policy (ENLP)
                         Segment List
                             Shared BLI
                             Weight
                             Segment
                             Segment
                             ...
                             ...

4.  Procedures

   When a candidate path of SR Policy is a bounded-latency routing path,
   the originating node of SR policy MUST include the associated bounded
   latency information in the BGP Tunnel Encapsulation Attribute of the
   BGP SR Policy.  The other fields and attributes in BGP SR Policy
   should follows the mechanism as defined
   in[I-D.ietf-idr-segment-routing-te-policy].

   When a BGP speaker receives an SR Policy which is acceptable and
   usable according to the rules as defined
   in[I-D.ietf-idr-segment-routing-te-policy] , and the SR Policy
   candidate path selected as the best candidate path is a bounded-
   latency path, the receiver node of the SR Policy MUST encapsulate the
   specific bounded latency information to the header of packets steered
   to the SR Policy.  For SR Policy with IPv6 data plane and MPLS data
   plane, the possible approach is to encapsulate the BLI to the packet
   using the mechanism defined in[I-D.yzz-detnet-enhanced-data-plane]
   and[I-D.geng-spring-sr-enhanced-detnet].

5.  IANA Considerations

   IANA is requested to make the assignment from the "BGP Tunnel
   Encapsulation Attribute sub-TLVs" registry as follows.

Zhang, et al.            Expires 12 January 2023                [Page 6]
Internet-Draft              Abbreviated-Title                  July 2022

  +-----------------+---------------------------------+----------------+
  |       Value     |               Name              |     Reference  |
  +-----------------+---------------------------------+----------------+
  |       TBD1      |        BLI List sub-TLV         | This document  |
  +-----------------+---------------------------------+----------------+
  |       TBD2      |       Shared BLI sub-TLV        | This document  |
  +-----------------+---------------------------------+----------------+

6.  Security Considerations

   TBD

7.  Acknowledgements

8.  Normative References

   [I-D.geng-spring-sr-enhanced-detnet]
              Geng, X., Li, Z., and T. Zhou, "Segment Routing for
              Enhanced DetNet", Work in Progress, Internet-Draft, draft-
              geng-spring-sr-enhanced-detnet-00, 11 July 2022,
              <https://www.ietf.org/archive/id/draft-geng-spring-sr-
              enhanced-detnet-00.txt>.

   [I-D.ietf-detnet-bounded-latency]
              Finn, N., Boudec, J. L., Mohammadpour, E., Zhang, J., and
              B. Varga, "DetNet Bounded Latency", Work in Progress,
              Internet-Draft, draft-ietf-detnet-bounded-latency-10, 8
              April 2022, <https://www.ietf.org/archive/id/draft-ietf-
              detnet-bounded-latency-10.txt>.

   [I-D.ietf-idr-segment-routing-te-policy]
              Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P.,
              Jain, D., and S. Lin, "Advertising Segment Routing
              Policies in BGP", Work in Progress, Internet-Draft, draft-
              ietf-idr-segment-routing-te-policy-18, 16 June 2022,
              <https://www.ietf.org/archive/id/draft-ietf-idr-segment-
              routing-te-policy-18.txt>.

   [I-D.ietf-spring-segment-routing-policy]
              Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
              P. Mattes, "Segment Routing Policy Architecture", Work in
              Progress, Internet-Draft, draft-ietf-spring-segment-
              routing-policy-22, 22 March 2022,
              <https://www.ietf.org/archive/id/draft-ietf-spring-
              segment-routing-policy-22.txt>.

Zhang, et al.            Expires 12 January 2023                [Page 7]
Internet-Draft              Abbreviated-Title                  July 2022

   [I-D.yzz-detnet-enhanced-data-plane]
              Yang, F., Zhou, T., and L. Zhang, "DetNet Enhanced Data
              Plane", Work in Progress, Internet-Draft, draft-yzz-
              detnet-enhanced-data-plane-00, 10 July 2022,
              <https://www.ietf.org/archive/id/draft-yzz-detnet-
              enhanced-data-plane-00.txt>.

   [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

   Li Zhang
   Huawei
   Email: zhangli344@huawei.com

   Xuesong Geng
   Huawei
   Email: gengxuesong@huawei.com

   Zhenbin Li
   Huawei
   Email: lizhenbin@huawei.com

Zhang, et al.            Expires 12 January 2023                [Page 8]