OSPF Extension for Prefix Originator
draft-ietf-lsr-ospf-prefix-originator-01
LSR Working Group A. Wang
Internet-Draft China Telecom
Intended status: Standards Track A. Lindem
Expires: January 2, 2020 Cisco Systems
J. Dong
Huawei Technologies
K. Talaulikar
P. Psenak
Cisco Systems
July 1, 2019
OSPF Extension for Prefix Originator
draft-ietf-lsr-ospf-prefix-originator-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 multi-area OSPF
use cases.
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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. Extended LSA Elements of Procedure . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
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
[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
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