OSPF Extension for Prefix Originator
draft-wang-lsr-ospf-prefix-originator-ext-01

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LSR Working Group                                                A. Wang
Internet-Draft                                             China Telecom
Intended status: Standards Track                               A. Lindem
Expires: July 8, 2019                                      Cisco Systems
                                                                 J. Dong
                                                     Huawei Technologies
                                                           K. Talaulikar
                                                               P. Psenak
                                                           Cisco Systems
                                                         January 4, 2019

                  OSPF Extension for Prefix Originator
              draft-wang-lsr-ospf-prefix-originator-ext-01

Abstract

   This document describes OSPFv2 and OSPFv3 encodings to advertise the
   router-id of the originator of inter-area prefixes for OSPFv2 and
   OSPFv3 LSAs, which are needed in several use cases in several multi-
   area OSPF use cases.

Status of This Memo

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   This Internet-Draft will expire on July 8, 2019.

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   Copyright (c) 2019 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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   (https://trustee.ietf.org/license-info) in effect on the date of
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Wang, et al.              Expires July 8, 2019                  [Page 1]
Internet-Draft             OSPF-Inter-Area-Ext              January 2019

   carefully, as they describe your rights and restrictions with respect
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

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.  Extended LSA Elements of Procedure  . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   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

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

   However, in inter-area scenarios, the Area Border Router (ABR) does
   not advertise the originating OSPF router-id for inter-area prefixes.
   An OSPF router in one area doesn't know where the prefixes really
   came from and can't determine the router that originated 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 ensure the ingress LSR constructs the
   right Label stack.

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