IGP Flexible Algorithms (Flexalgo) In IP Networks
draft-bonica-lsr-ip-flexalgo-00
LSR Working Group W. Britto
Internet-Draft S. Hegde
Intended status: Standards Track P. Kaneriya
Expires: April 2, 2021 R. Shetty
R. Bonica
Juniper Networks
September 29, 2020
IGP Flexible Algorithms (Flexalgo) In IP Networks
draft-bonica-lsr-ip-flexalgo-00
Abstract
An IGP Flexible Algorithm computes a constraint-based path and maps
that path to an identifier. As currently defined, Flexalgo can only
map the paths that it computes to Segment Routing (SR) identifiers.
Therefore, Flexalgo cannot be deployed in the absence of SR.
This document extends Flexalgo, so that it can map the paths that it
computes to IP addresses. This allows Flexalgo to be deployed in any
IP network, even in the absence of SR.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Egress Node Procedures . . . . . . . . . . . . . . . . . . . 3
4. Advertising Flexible Algorithm Definitions (FAD) . . . . . . 3
5. Advertising IP Reachability Using a Flexalgo . . . . . . . . 4
5.1. The ISIS IPv4 Flexalgo Prefix Reachability TLV . . . . . 4
5.2. The ISIS IPv6 Flexalgo Prefix Reachability TLV . . . . . 5
5.3. The ISIS MT IPv4 Flexalgo Prefix Reachability TLV . . . . 5
5.4. The ISIS MT IPv6 Flexalgo Prefix Reachability TLV . . . . 6
5.5. The OSPFv2 Flexalgo IP Prefix Opaque LSA . . . . . . . . 6
6. Advertising IGP Algorithm Support . . . . . . . . . . . . . . 8
6.1. The ISIS IGP Algorithm Sub-TLV . . . . . . . . . . . . . 8
6.2. The OSPFv2 IGP Algorithm TLV . . . . . . . . . . . . . . 9
7. Advertising Link Attributes . . . . . . . . . . . . . . . . . 10
8. Calculating Constraint-Based Paths . . . . . . . . . . . . . 10
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
10. Security Considerations . . . . . . . . . . . . . . . . . . . 11
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
12.1. Normative References . . . . . . . . . . . . . . . . . . 11
12.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
An IGP Flexible Algorithm (Flexalgo) [I-D.ietf-lsr-flex-algo]:
o Computes a constraint-based path to an egress node.
o Maps that path to an identifier.
As currently defined, Flexalgo can only map the paths that it
computes to:
o A Segment Routing (SR) [RFC8402] Segment Identifier (SID).
o An SRv6 [I-D.ietf-spring-srv6-network-programming] locator.
Therefore, Flexalgo cannot be deployed in the absence of SR and SRv6.
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This document extends Flexalgo, allowing it to map the paths that it
computes to:
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