Bidirectional Forwarding Detection (BFD) for Segment Routing Policies for Traffic Engineering
draft-ali-spring-bfd-sr-policy-02

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Last updated 2018-10-22
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SPRING                                                            Z. Ali
Internet-Draft                                             K. Talaulikar
Intended status: Informational                               C. Filsfils
Expires: April 25, 2019                                        N. Nainar
                                                            C. Pignataro
                                                           Cisco Systems
                                                        October 22, 2018

 Bidirectional Forwarding Detection (BFD) for Segment Routing Policies
                        for Traffic Engineering
                   draft-ali-spring-bfd-sr-policy-02

Abstract

   Segment Routing (SR) allows a headend node to steer a packet flow
   along any path using a segment list which is referred to as a SR
   Policy.  Intermediate per-flow states are eliminated thanks to source
   routing.  The header of a packet steered in an SR Policy is augmented
   with the ordered list of segments associated with that SR Policy.
   Bidirectional Forwarding Detection (BFD) is used to monitor different
   kinds of paths between node.  BFD mechanisms can be also used to
   monitor the availability of the path indicated by a SR Policy and to
   detect any failures.  Seamless BFD (S-BFD) extensions provide a
   simplified mechanism which is suitable for monitoring of paths that
   are setup dynamically and on a large scale.

   This document describes the use of Seamless BFD (S-BFD) mechanism to
   monitor the SR Policies that are used for Traffic Engineering (TE) in
   SR deployments.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

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Internet-Draft         BFD for SR Policies for TE           October 2018

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   This Internet-Draft will expire on April 25, 2019.

Copyright Notice

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

   This document is subject to BCP 78 and the IETF Trust's Legal
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Choice of S-BFD over BFD  . . . . . . . . . . . . . . . . . .   4
   3.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  S-BFD Discriminator . . . . . . . . . . . . . . . . . . .   5
     3.2.  S-BFD session Initiation by SBFDInitiator . . . . . . . .   5
     3.3.  Controlled Return Path  . . . . . . . . . . . . . . . . .   6
     3.4.  S-BFD Echo Recommendation . . . . . . . . . . . . . . . .   7
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   6.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   Segment Routing (SR) ([RFC8402]) allows a headend node to steer a
   packet flow along any path for specific objectives like Traffic
   Engineering (TE) and to provide it treatment according to the
   specific established service level agreement (SLA) for it.
   Intermediate per-flow states are eliminated thanks to source routing.
   The headend node steers a flow into an SR Policy.  The header of a

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