IGP Flexible Algorithms (Flexalgo) In IP Networks
draft-bonica-lsr-ip-flexalgo-00

Document Type Active Internet-Draft (individual)
Authors William Britto  , Shraddha Hegde  , Parag Kaneriya  , Rejesh Shetty  , Ron Bonica 
Last updated 2020-09-29
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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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   This Internet-Draft will expire on April 2, 2021.

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   Copyright (c) 2020 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
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of

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   publication of this document.  Please review these documents
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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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