OSPF Prefix Originator Extension
draft-ietf-lsr-ospf-prefix-originator-04
LSR Working Group A. Wang
Internet-Draft China Telecom
Intended status: Standards Track A. Lindem
Expires: March 15, 2020 Cisco Systems
J. Dong
Huawei Technologies
P. Psenak
K. Talaulikar
Cisco Systems
September 12, 2019
OSPF Prefix Originator Extension
draft-ietf-lsr-ospf-prefix-originator-04
Abstract
This document defines Open Shortest Path First (OSPF) encodings to
advertise the router-id of the originator of inter-area prefixes for
OSPFv2 and OSPFv3 Link-State Advertisements (LSAs). The source
originator is needed in several multi-area OSPF use cases.
Status of This Memo
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This Internet-Draft will expire on March 15, 2020.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Inter-Area Prefix Source Advertisement Use Cases . . . . . . 4
5. Prefix Source Router-ID sub-TLV . . . . . . . . . . . . . . . 5
6. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 7
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
10.1. Normative References . . . . . . . . . . . . . . . . . . 7
10.2. Informative References . . . . . . . . . . . . . . . . . 9
Appendix A. Inter-Area Topology Retrieval Process . . . . . . . 9
Appendix B. Special Considerations on Inter-Area Topology
Retrieval . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
[I-D.ietf-ospf-mpls-elc] defines mechanisms to advertise Entropy
Readable Label Depth (ERLD) for ingress Label Switching Routers (LSR)
to discover other LSR's capability of performing Entropy Label based
load-balancing in MPLS networks. The ingress LSR can use this
information to construct the appropriate label stack for specific
traffic requirements, especially in segment routed networks and other
deployments requiring stacked LSPs.
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 the origin area of inter-area
prefixes and can't determine the router that originated these
prefixes or the ERLD capabilities of the destination. Therefore, it
is necessary to advertise the originator of these inter-area prefixes
to ensure the ingress LSR can construct the appropriate label stack.
More generally, [RFC8476] 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
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