Overheads Reduction for IS-IS Enabled Spine-Leaf Networks
draft-chen-isis-sl-overheads-reduction-00

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Network Working Group                                            Z. Chen
Internet-Draft                                                     X. Xu
Intended status: Standards Track                     Huawei Technologies
Expires: July 10, 2017                                   January 6, 2017

       Overheads Reduction for IS-IS Enabled Spine-Leaf Networks
               draft-chen-isis-sl-overheads-reduction-00

Abstract

   When a Spine-Leaf topology adopts the Intermediate System to
   Intermediate System (IS-IS) routing protocol, the Leaf node receives
   Link State Packets (LSPs) from all the other nodes thus having the
   entire routing information of the topology.  This is usually
   considered unnecessary and costly.  This document describes a
   solution to this problem by assigning different area identifiers
   (AIDs) to the Leaf nodes.  The solution requires that an IS-IS router
   SHOULD check a Level-1 LSP's AIDs before it advertises the LSP to its
   neighbor.

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
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   This Internet-Draft will expire on July 10, 2017.

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Internet-Draft    IS-IS Spine-Leaf Overheads Reduction      January 2017

Copyright Notice

   Copyright (c) 2017 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.  Solution Description  . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Area ID Assignment  . . . . . . . . . . . . . . . . . . .   3
     2.2.  Area ID Checking  . . . . . . . . . . . . . . . . . . . .   5
     2.3.  Default Route Advertising . . . . . . . . . . . . . . . .   6
   3.  Discussions . . . . . . . . . . . . . . . . . . . . . . . . .   7
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   Spine-Leaf topology (a.k.a., CLOS topology) is widely used in today's
   datacenter and campus networks.  When the Spine-Leaf topology runs
   the Intermediate System to Intermediate System (IS-IS) routing
   protocol, each Leaf node will receive Link State Packets (LSPs) from
   all the other nodes and have the entire routing information of the
   topology.  This is usually considered to be unnecessary and costly
   because the Leaf node only needs to know its default gateways (i.e.,
   the Spine nodes it connects to), and the LSPs generated by the other
   Leaf nodes benefit nothing for it to forward traffic.

   To avoid Leaf nodes from learning the unnecessary LSPs from one
   another, [IS-IS-SL-Extension] proposes a new TLV of the IS-IS Hello
   (IIH) PDU to differentiate Spine/Leaf nodes and LSPs generated by
   Leaf nodes will be blocked at Spine nodes.  Additionally, each Leaf
   node sets the Spine nodes it connects to as its default gateways.

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