OSPF Reverse Metric
draft-ketant-lsr-ospf-reverse-metric-02

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Link State Routing                                         K. Talaulikar
Internet-Draft                                                 P. Psenak
Intended status: Standards Track                     Cisco Systems, Inc.
Expires: February 21, 2020                                   H. Johnston
                                                               AT&T Labs
                                                         August 20, 2019

                          OSPF Reverse Metric
                draft-ketant-lsr-ospf-reverse-metric-02

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.

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/.

   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 February 21, 2020.

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Copyright Notice

   Copyright (c) 2019 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 Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   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.

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