OSPF Extension for Prefix Originator
draft-wang-lsr-ospf-prefix-originator-ext-00

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Last updated 2018-10-18
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LSR Working Group                                                A. Wang
Internet-Draft                                             China Telecom
Intended status: Standards Track                               A. Lindem
Expires: April 18, 2019                                    Cisco Systems
                                                                 J. Dong
                                                     Huawei Technologies
                                                           K. Talaulikar
                                                               P. Psenak
                                                           Cisco Systems
                                                        October 15, 2018

                  OSPF Extension for Prefix Originator
              draft-wang-lsr-ospf-prefix-originator-ext-00

Abstract

   This document describes method to transfer the source router id of
   inter-area prefixes for OSPFv2 [RFC7684]and OSPFv3 [RFC8362], which
   is needed in several use cases in OSPF inter-area scenario.

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   Copyright (c) 2018 IETF Trust and the persons identified as the
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   This document is subject to BCP 78 and the IETF Trust's Legal
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Wang, et al.             Expires April 18, 2019                 [Page 1]
Internet-Draft             OSPF-Inter-Area-Ext              October 2018

   to this document.  Code Components extracted from this document must
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   3
   3.  Scenario Description  . . . . . . . . . . . . . . . . . . . .   3
   4.  Prefix Source Router ID sub TLV . . . . . . . . . . . . . . .   4
   5.  Extend LSA Operation Procedure  . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   8.  Acknowledgement . . . . . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Appendix A.  Inter-Area Topology Retrieval Process  . . . . . . .   7
   Appendix B.  Special Considerations on Inter-Area Topology
                Retrieval  . . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Draft [I-D.ietf-ospf-mpls-elc] defines mechanisms to signal Entropy
   Label Capability(ELC) and Entropy Readable Label Depth (ERLD) for the
   ingress LSR to know each LSR's capability of reading the maximum
   label stack depth and performing EL-based load-balancing in MPLS
   network.  After knowing this information, the ingress LSR can push
   the appropriate label stack for specific FEC trafffic, especially in
   segment routing environment or in other stacked LSPs scenarios.

   But in OSPF inter-area scenario, the prefixes originator information
   in another area is omitted by ABR router, all prefixes are attached
   behind the ABR.  Router in one area doesn't know where the prefixes
   really come from, can't decide the associated router of the inter-
   area prefixes and then can't judge the ELC and ERLD capabilities of
   the destination.  It is necessary to transfer the originator
   information of these inter-area prefixes to assist the ingress LSR
   does the right Label stack action.

   More generally, draft [I-D.ietf-ospf-segment-routing-msd] defines the
   mechanism to advertise multiple types of supported Maximum SID
   Depths(MSD) at node and/or link granularity.  These information will
   be referred when the head end router starts to send the traffic to
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