ISIS Segment Routing Flexible Algorithm
draft-hegdeppsenak-isis-sr-flex-algo-02

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Network Working Group                                     P. Psenak, Ed.
Internet-Draft                                             Cisco Systems
Intended status: Standards Track                           S. Hegde, Ed.
Expires: August 20, 2018                          Juniper Networks, Inc.
                                                             C. Filsfils
                                                     Cisco Systems, Inc.
                                                                A. Gulko
                                                         Thomson Reuters
                                                       February 16, 2018

                ISIS Segment Routing Flexible Algorithm
              draft-hegdeppsenak-isis-sr-flex-algo-02.txt

Abstract

   IGP protocols traditionally compute best paths over the network based
   on the IGP metric assigned to the links.  Many network deployments
   use RSVP-TE based or Segment Routing based Traffic Engineering to
   enforce traffic over a path that is computed using different metrics
   or constraints than the shortest IGP path.  Various mechanisms are
   used to steer the traffic towards such traffic engineered paths.
   This document proposes a solution that allows IGPs themselves to
   compute constraint based paths over the network without the use of
   the above mentioned traffic engineering technologies.

Status of This Memo

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   This Internet-Draft will expire on August 20, 2018.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Psenak, et al.           Expires August 20, 2018                [Page 1]
Internet-Draft     ISIS Segment Routing Flex Algorithm     February 2018

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements notation . . . . . . . . . . . . . . . . . .   3
   2.  Flexible Algorithm  . . . . . . . . . . . . . . . . . . . . .   3
   3.  Flexible Algorithm Advertisement  . . . . . . . . . . . . . .   3
   4.  Flexible Algorithm Definition Advertisement . . . . . . . . .   4
     4.1.  Flexible Algorithm Definition Sub-TLV . . . . . . . . . .   4
     4.2.  Flexible Algorithm Exclude Admin Group Sub-TLV  . . . . .   7
     4.3.  Flexible Algorithm Include Admin Group Sub-TLVs . . . . .   7
   5.  Calculation of Flexible Algorithm Paths . . . . . . . . . . .   8
   6.  Backward Compatibility  . . . . . . . . . . . . . . . . . . .  10
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
     8.1.  Sub TLVs for Type 242 . . . . . . . . . . . . . . . . . .  10
     8.2.  New Sub-Sub-TLV registry  . . . . . . . . . . . . . . . .  10
       8.2.1.  Flexible Algorithm Definition TLV Metric Registry . .  11
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  11
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  12
     10.2.  Informative References . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   IGP computed path based on the shortest IGP metric must often be
   replaced by traffic engineered path due to the traffic requirements
   which are not reflected in the IGP metric.  Some networks engineer
   the IGP metric assignments in a way that the IGP Metric reflects the
   link bandwidth or delay.  If, for example, the IGP metric is
   reflecting the bandwidth on the link and the application traffic is
   delay sensitive, the best IGP path may not reflect the best path from
   such application's perspective.

   To overcome such IGP limitation, various sorts of traffic engineering
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