OSPF Reverse Metric
draft-ietf-lsr-ospf-reverse-metric-01
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
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This Internet-Draft will expire on December 31, 2020.
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Internet-Draft OSPF Reverse Metric June 2020
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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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