OSPF Extend for Inter-Area Topology Retrieval
draft-wang-lsr-ospf-inter-area-topology-ext-00

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LSR Working Group                                                A. Wang
Internet-Draft                                             China Telecom
Intended status: Standards Track                           June 28, 2018
Expires: December 30, 2018

             OSPF Extend for Inter-Area Topology Retrieval
             draft-wang-lsr-ospf-inter-area-topology-ext-00

Abstract

   This document describes method to transfer the source router id of
   inter-area prefixes for OSPFv2 [RFC2328] and OSPFv3 [RFC5340], which
   is needed in topology retrieval processing for inter-area scenario.

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 30, 2018.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   2
   3.  Inter-Area Topology Retrieval Scenario  . . . . . . . . . . .   3
     3.1.  OSPFv2 Extend Solution (IPv4 Source Router ID)  . . . . .   4
     3.2.  OSPFv3 Extend Solution (IPv6 Source Router ID)  . . . . .   5
     3.3.  Prefix Source Router ID sub TLV . . . . . . . . . . . . .   7
     3.4.  Extend LSA generate process . . . . . . . . . . . . . . .   8
     3.5.  Inter-Area Topology Retrieval Process . . . . . . . . . .   8
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   BGP-LS [RFC7752] describes the methodology that using BGP protocol to
   transfer the Link-State information.  Such method can enable SDN
   controller to collect the underlay network topology automatically.

   But if the underlay network is divided into multi area and running
   OSPF protocol, it is not easy for the SDN controller to rebuild the
   multi-area topology, because normally the ABR that locates on the
   boundary of different area will hide the detail topology information
   in non-backbone area, and the router in backbone area that runs BGP-
   LS protocol can only get and report the summary network information
   in non-backbone area.

   [RFC7794] introduces "IPv4/IPv6 Source Router IDs" TLV to label the
   source of the prefixes redistributed from different Level, this TLV
   can be used to reconstruct the detail overall topology within level 1
   and level 2.  Such solution can also be applied into network that run
   OSPF protocol, but the related LSP message must be redefined.

   This draft gives such solution for the OSPF v2 and OSPF v3 protocol.

2.  Conventions used in this document

   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] .

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3.  Inter-Area Topology Retrieval Scenario

   Fig.1 illustrates the topology retrieval scenario when OSPF is
   running in multi-area.  R0-R4 are routers in backbone area,
   S1-S4,T1-T4 are interal router in area 1 and area 2 respectively.  R1
   and R3 are border routers between area 0 and area 1; R2 and R4 are
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