TVR                                                             Z. Zhang
Internet-Draft                                                     H. Wu
Intended status: Standards Track                         ZTE Corporation
Expires: 9 September 2023                                   8 March 2023


        IS-IS and OSPF extensions for TVR (Time-Variant Routing)
                     draft-zw-tvr-igp-extensions-00

Abstract

   TVR needs IGP to calculate different results depending on the time,
   without convergence after the detection of link or nodes.  IGP nodes
   need to learn the predictable and scheduled changes in advance.  This
   document defines the IGP extensions for predictable and scheduled
   changes of TVR.

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 9 September 2023.

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.




Zhang & Wu              Expires 9 September 2023                [Page 1]

Internet-Draft              Abbreviated Title                 March 2023


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Time Variant Algorithm  . . . . . . . . . . . . . . . . . . .   3
   4.  Time Variant sub-TLVs of IS-IS and OSPF FAD Sub-TLV . . . . .   3
   5.  Handling of the time variant sub-TLV  . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
     6.1.  IGP Metric-type Registry  . . . . . . . . . . . . . . . .   4
     6.2.  IS-IS Registry  . . . . . . . . . . . . . . . . . . . . .   4
     6.3.  OSPF Registry . . . . . . . . . . . . . . . . . . . . . .   4
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   [I-D.birrane-tvr-use-cases] and [I-D.king-tvr-ntn-challanges]
   describe a new challenge for non-terrestrial networks.  In these
   networks, there are predictable and scheduled changes of link or
   nodes.  The affected nodes which connected the changing link or node
   advertise the changes after finding the changes.  After convergence
   all the nodes calculate a new routing table.  But for the predictable
   and scheduled changes, the nodes can advertise the changes and do the
   calculation in advance to reduce the convergence time.

   This document defines the a set of extensions to IS-IS, OSPFv2 and
   OSPFv3 for predictable and scheduled changes of TVR.  These
   extensions can be advertised by the node self which has predictable
   and scheduled changes, or by the node which connected or adjacenct to
   the node which has predictable and scheduled changes.

1.1.  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 [RFC2119].

2.  Terminology

   TBD.







Zhang & Wu              Expires 9 September 2023                [Page 2]

Internet-Draft              Abbreviated Title                 March 2023


3.  Time Variant Algorithm

   The predictable and scheduled changes can be looked as a net of new
   constrains which defined in [RFC9350].  The new constrains are
   advertised as new sub-tlvs.

4.  Time Variant sub-TLVs of IS-IS and OSPF FAD Sub-TLV

   A new type of Metric-Type is defined for time variant in IS-IS FAD
   sub-TLV which defined in section 5.1 [RFC9350] and OSPF FAD sub-TLV
   which defined in section 5.2 [RFC9350].

   A new Time Variant sub-TLV is advertised as a sub-TLV of IS-IS FAD
   sub-TLV and OSPF FAD sub-TLV.  The Time Variant sub-TLV has following
   formats:

       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     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Metric1                              |
      |                       Time-slot1-begin                        |
      |                       Time-slot1-end                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Metric2                              |
      |                       Time-slot2-begin                        |
      |                       Time-slot2-end                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                               .                               |
      .                               .                               .
      |                               .                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Metric[m]                            |
      |                       Time-slot[m]-begin                      |
      |                       Time-slot[m]-end                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                  Figure 1

   Type: 1-octet.  TBD (To be assigned by IANA).

   Length: 1-octet.  The number of the set of metric and time-slot.

   Metric: 4-octet.  The metric value of specific time slot.  The
   value of 0xffffffff indicates unreachable.

   Time-slot-begin: 4-octet.  The begin time of this time-slot.



Zhang & Wu              Expires 9 September 2023                [Page 3]

Internet-Draft              Abbreviated Title                 March 2023


   Time-slot-end: 4-octet.  The end time of this time-slot.

5.  Handling of the time variant sub-TLV

   The handling follows the definition in [RFC9350], except one or more
   timers are scheduled for different time-slot carried in time variant
   sub-tlv.  When a scheduled time-slot is coming, the associated
   routing table needs to be calculated with the associated metric.

6.  IANA Considerations

   The document requests new allocations from the IANA registries as
   follows:

6.1.  IGP Metric-type Registry

   IANA is requested to allocate a new code points from the "IGP Metric-
   Type" registry.

              +======+=====================+===============+
              | Type |     Description     |   Reference   |
              +======+=====================+===============+
              | TBD1 | Time Variant metric | This Document |
              +------+---------------------+---------------+

                         Table 1: IGP Metric-Type

6.2.  IS-IS Registry

   IANA is requested to allocate a new code points from the "IS-IS Sub-
   Sub-TLVs for Flexible Algorithm Definition Sub-TLV" registry.

                  +======+==============+===============+
                  | Type | Description  |   Reference   |
                  +======+==============+===============+
                  | TBD2 | Time Variant | This Document |
                  +------+--------------+---------------+

                         Table 2: IS-IS TVR sub-TLV

6.3.  OSPF Registry

   IANA is requested to allocate a new code points from the "OSPF
   Flexible Algorithm Definition TLV Sub-TLVs" registry.







Zhang & Wu              Expires 9 September 2023                [Page 4]

Internet-Draft              Abbreviated Title                 March 2023


                  +======+==============+===============+
                  | Type | Description  |   Reference   |
                  +======+==============+===============+
                  | TBD3 | Time Variant | This Document |
                  +------+--------------+---------------+

                         Table 3: OSPF TVR sub-TLV

7.  Security Considerations

   This document does not introduce more security consideration than
   [RFC9350].

8.  References

8.1.  Normative References

   [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>.

   [RFC9350]  Psenak, P., Ed., Hegde, S., Filsfils, C., Talaulikar, K.,
              and A. Gulko, "IGP Flexible Algorithm", RFC 9350,
              DOI 10.17487/RFC9350, February 2023,
              <https://www.rfc-editor.org/info/rfc9350>.

8.2.  Informative References

   [I-D.birrane-tvr-use-cases]
              Birrane, E. J., "TVR (Time-Variant Routing) Use Cases",
              Work in Progress, Internet-Draft, draft-birrane-tvr-use-
              cases-00, 24 October 2022,
              <https://datatracker.ietf.org/doc/html/draft-birrane-tvr-
              use-cases-00>.

   [I-D.king-tvr-ntn-challanges]
              King, D. and K. Shortt, "Time Variant Challenges for Non-
              Terrestrial Networks", Work in Progress, Internet-Draft,
              draft-king-tvr-ntn-challanges-00, 17 January 2023,
              <https://datatracker.ietf.org/doc/html/draft-king-tvr-ntn-
              challanges-00>.

Authors' Addresses

   Zheng Zhang
   ZTE Corporation
   China



Zhang & Wu              Expires 9 September 2023                [Page 5]

Internet-Draft              Abbreviated Title                 March 2023


   Email: zhang.zheng@zte.com.cn


   Haisheng Wu
   ZTE Corporation
   China
   Email: wu.haisheng@zte.com.cn












































Zhang & Wu              Expires 9 September 2023                [Page 6]