Area Proxy for IS-IS
draft-li-lsr-isis-area-proxy-00

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Internet Engineering Task Force                                    T. Li
Internet-Draft                                                   S. Chen
Intended status: Standards Track                         Arista Networks
Expires: April 5, 2020                                   October 3, 2019

                          Area Proxy for IS-IS
                    draft-li-lsr-isis-area-proxy-00

Abstract

   Link state routing protocols have hierarchical abstraction already
   built into them.  However, when lower levels are used for transit,
   they must expose their internal topologies to each other, leading to
   scale issues.

   To avoid this, this document discusses extensions to the IS-IS
   routing protocol that would allow level 1 areas to provide transit,
   yet only inject an abstraction of the level 1 topology into level 2.
   Each level 1 area is represented as a single level 2 node, thereby
   enabling greater scale.

Status of This Memo

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   This Internet-Draft will expire on April 5, 2020.

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   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
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   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents

Li & Chen                 Expires April 5, 2020                 [Page 1]
Internet-Draft                 Area Proxy                   October 2019

   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Area Proxy  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Inside Router Functions . . . . . . . . . . . . . . . . . . .   5
     3.1.  The Area Proxy Router Capability  . . . . . . . . . . . .   5
     3.2.  Level 2 SPF Computation . . . . . . . . . . . . . . . . .   5
   4.  Area Leader Functions . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Area Leader Election  . . . . . . . . . . . . . . . . . .   6
     4.2.  Redundancy  . . . . . . . . . . . . . . . . . . . . . . .   6
     4.3.  Area Proxy System Identifier TLV  . . . . . . . . . . . .   6
     4.4.  Area Proxy LSP Generation . . . . . . . . . . . . . . . .   7
   5.  Inside Edge Router Functions  . . . . . . . . . . . . . . . .   8
     5.1.  Generating L2 IIHs to Outside Routers . . . . . . . . . .   8
     5.2.  Filtering LSP information . . . . . . . . . . . . . . . .   8
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   9
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  10
     9.3.  URIs  . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   The IS-IS routing protocol IS-IS [ISO10589] currently supports a two-
   level hierarchy of abstraction.  The fundamental unit of abstraction
   is the 'area', which is a (hopefully) connected set of systems
   running IS-IS at the same level.  Level 1, the lowest level, is
   abstracted by routers that participate in both Level 1 and Level 2,
   and they inject area information into Level 2.  Level 2 systems
   seeking to access Level 1, use this abstraction to compute the
   shortest path to the Level 1 area.  The full topology database of
   Level 1 is not injected into Level 2, only a summary of the address
   space contained within the area, so the scalability of the Level 2
   Link State Database (LSDB) is protected.

   This works well if the Level 1 area is tangential to the Level 2
   area.  This also works well if there are several routers in both