Host Router Support for OSPFv2
draft-ietf-ospf-ospfv2-hbit-12

Document Type Active Internet-Draft (lsr WG)
Last updated 2019-12-26 (latest revision 2019-12-18)
Replaces draft-keyupate-ospf-ospfv2-hbit
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OSPF                                                            K. Patel
Internet-Draft                                                    Arrcus
Updates: 6987 (if approved)                            P. Pillay-Esnault
Intended status: Standards Track                          PPE Consulting
Expires: June 20, 2020                                       M. Bhardwaj
                                                            S. Bayraktar
                                                           Cisco Systems
                                                       December 18, 2019

                     Host Router Support for OSPFv2
                     draft-ietf-ospf-ospfv2-hbit-12

Abstract

   The Open Shortest Path First Version 2 (OSPFv2) protocol does not
   have a mechanism for a node to repel transit traffic if it is on the
   shortest path.  This document defines a bit (Host-bit) that enables a
   router to advertise that it is a non-transit router.  It also
   describes the changes needed to support the H-bit in the domain.  In
   addition, this document updates RFC 6987 to advertise type-2 External
   and Not-So-Stubby-Area (NSSA) Link State Advertisements (LSAs) with a
   high cost in order to repel traffic effectively.

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
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   This Internet-Draft will expire on June 20, 2020.

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

Patel, et al.             Expires June 20, 2020                 [Page 1]
Internet-Draft                                             December 2019

   (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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Host-bit Support  . . . . . . . . . . . . . . . . . . . . . .   3
   4.  SPF Modifications . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Auto Discovery and Backward Compatibility . . . . . . . . . .   6
   6.  OSPF AS-External-LSAs/NSSA LSAs with Type 2 Metrics . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     10.2.  Informative References . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   The OSPFv2 protocol specifies a Shortest Path First (SPF) algorithm
   that identifies transit vertices based on their adjacencies.
   Therefore, OSPFv2 does not have a mechanism to prevent traffic
   transiting a participating node if it is a transit vertex in the only
   existing or shortest path to the destination.  The use of metrics to
   make the node undesirable can help to repel traffic only if an
   alternative better route exists.

   A mechanism to move traffic away from the shortest path is
   particularly useful for a number of use cases:

   1.  To gracefully isolate a router to avoid blackhole scenarios when
       there is a reload and possible long reconvergence times.

   2.  Closet Switches are usually not used for transit traffic but need
       to participate in the topology.

   3.  Overloaded routers could use such a capability to temporarily
       repel traffic until they stabilize.

   4.  BGP Route reflectors known as virtual Route Reflectors (vRRs),
       that are not in the forwarding path but are in central locations

Patel, et al.             Expires June 20, 2020                 [Page 2]
Internet-Draft                                             December 2019
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