OSPF Reverse Metric
draft-ietf-lsr-ospf-reverse-metric-01

Document Type Active Internet-Draft (lsr WG)
Authors Ketan Talaulikar  , Peter Psenak  , Hugh Johnston 
Last updated 2020-11-25 (latest revision 2020-06-29)
Replaces draft-ketant-lsr-ospf-reverse-metric
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Link State Routing                                         K. Talaulikar
Internet-Draft                                                 P. Psenak
Intended status: Standards Track                     Cisco Systems, Inc.
Expires: December 31, 2020                                   H. Johnston
                                                               AT&T Labs
                                                           June 29, 2020

                          OSPF Reverse Metric
                 draft-ietf-lsr-ospf-reverse-metric-01

Abstract

   This document specifies the extensions to OSPF that enables a router
   to signal to its neighbor the metric that the neighbor should use
   towards itself using link-local advertisement between them.  The
   signalling of this reverse metric, to be used on link(s) towards
   itself, allows a router to influence the amount of traffic flowing
   towards itself and in certain use-cases enables routers to maintain
   symmetric metric on both sides of a link between them.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on December 31, 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

Talaulikar, et al.      Expires December 31, 2020               [Page 1]
Internet-Draft             OSPF Reverse Metric                 June 2020

   to this document.  Code Components extracted from this document must
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Symmetrical Metric Based on Reference Bandwidth . . . . .   3
     2.2.  Adaptive Metric Signaling . . . . . . . . . . . . . . . .   4
   3.  Solution  . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  LLS Reverse Metric TLV  . . . . . . . . . . . . . . . . . . .   6
   5.  LLS Reverse TE Metric TLV . . . . . . . . . . . . . . . . . .   6
   6.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . .   7
   7.  Backward Compatibility  . . . . . . . . . . . . . . . . . . .   9
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   10. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  10
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     12.2.  Informative References . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   Routers running the Open Shortest Path First (OSPFv2) [RFC2328] and
   OSPFv3 [RFC5340] routing protocols originate a Router-LSA (Link State
   Advertisement) that describes all its links to its neighbors and
   includes a metric which indicates its "cost" of reaching the neighbor
   over that link.  Consider two routers R1 and R2 that are connected
   via a link.  The metric for this link in direction R1->R2 is
   configured on R1 and in the direction R2->R1 is configured on R2.
   Thus the configuration on R1 influences the traffic that it forwards
   towards R2 but does not influence the traffic that it may receive
   from R2 on that same link.

   This document describes certain use-cases where it is desirable for a
   router to be able to signal what we call as the "reverse metric" (RM)
   to its neighbor to adjust the routing metric on the inbound
   direction.  When R1 signals its reverse metric on its link to R2,
   then R2 advertises this value as its metric to R1 in its Router-LSA
   instead of its locally configured value.  Once this information is
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