Policy Guided Prefixes with Routing In Fat Trees
draft-atlas-rift-pgp-01

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RIFT                                                            A. Atlas
Internet-Draft                                                Individual
Intended status: Standards Track                                Z. Zhang
Expires: October 27, 2019                               Juniper Networks
                                                          April 25, 2019

            Policy Guided Prefixes with Routing In Fat Trees
                        draft-atlas-rift-pgp-01

Abstract

   In a fat tree, it can be sometimes desirable to guide traffic to
   particular destinations or keep specific flows to certain paths.  In
   RIFT, this traffic steering/engineering is done by using policy-
   guided prefixes with their associated communities.  Routes based on
   policy-guided prefixes are preferred over regular routes.  Any node
   can originate a policy-guided prefix and advertise it in both north
   and south directions, and the calculation in both directions are
   distance vector based.

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 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
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   This Internet-Draft will expire on October 27, 2019.

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Copyright Notice

   Copyright (c) 2019 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
   Provisions Relating to IETF Documents
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Specification . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Ingress Filtering . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Applying Policy . . . . . . . . . . . . . . . . . . . . .   4
     2.3.  Store Policy-Guided Prefix for Route Computation and
           Regeneration  . . . . . . . . . . . . . . . . . . . . . .   5
     2.4.  Re-origination  . . . . . . . . . . . . . . . . . . . . .   6
     2.5.  Reachability Computation with PGP Consideration . . . . .   6
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   5.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   In a fat tree, it can be sometimes desirable to guide traffic to
   particular destinations or keep specific flows to certain paths.  In
   RIFT, this is done by using policy-guided prefixes with their
   associated communities.  Each community is an abstract value whose
   meaning is determined by configuration.  It is assumed that the
   fabric is under a single administrative control so that the meaning
   and intent of the communities is understood by all the nodes in the
   fabric.  Any node can originate a policy-guided prefix.

   Since RIFT uses distance vector concepts in a southbound direction,
   it is straightforward to add a policy-guided prefix to an S-TIE.  For
   easier troubleshooting, the approach taken in RIFT is that a node's
   southbound policy-guided prefixes are sent in its S-TIE and the
   receiver does inbound filtering based on the associated communities
   (an egress policy is imaginable but would lead to different S-TIEs
   per adjacency possibly which is not considered in RIFT protocol

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   procedures).  A southbound policy-guided prefix can only use links in
   the south direction.  If an PGP S-TIE is received on an East-West or