Area Proxy for IS-IS
draft-li-lsr-isis-area-proxy-04

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Last updated 2020-04-20
Replaces draft-li-lsr-isis-area-abstraction
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Internet Engineering Task Force                                    T. Li
Internet-Draft                                                   S. Chen
Intended status: Standards Track                         Arista Networks
Expires: October 22, 2020                                 April 20, 2020

                          Area Proxy for IS-IS
                    draft-li-lsr-isis-area-proxy-04

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 October 22, 2020.

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   Copyright (c) 2020 IETF Trust and the persons identified as the
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   This document is subject to BCP 78 and the IETF Trust's Legal
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Li & Chen               Expires October 22, 2020                [Page 1]
Internet-Draft                 Area Proxy                     April 2020

   carefully, as they describe your rights and restrictions with respect
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  Area Proxy  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Segment Routing . . . . . . . . . . . . . . . . . . . . .   5
   3.  Inside Router Functions . . . . . . . . . . . . . . . . . . .   6
     3.1.  The Area Proxy Router Capability  . . . . . . . . . . . .   6
     3.2.  Level 2 SPF Computation . . . . . . . . . . . . . . . . .   6
     3.3.  The Inside Node TLV . . . . . . . . . . . . . . . . . . .   7
   4.  Area Leader Functions . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Area Leader Election  . . . . . . . . . . . . . . . . . .   7
     4.2.  Redundancy  . . . . . . . . . . . . . . . . . . . . . . .   7
     4.3.  The Area Proxy TLV  . . . . . . . . . . . . . . . . . . .   8
       4.3.1.  The Area Proxy System Id Sub-TLV  . . . . . . . . . .   8
       4.3.2.  The Area Segment SID Sub-TLV  . . . . . . . . . . . .   9
     4.4.  Area Proxy LSP Generation . . . . . . . . . . . . . . . .  10
       4.4.1.  The Protocols Supported TLV . . . . . . . . . . . . .  10
       4.4.2.  The Area Address TLV  . . . . . . . . . . . . . . . .  10
       4.4.3.  The Dynamic Hostname TLV  . . . . . . . . . . . . . .  10
       4.4.4.  The IS Neighbors TLV  . . . . . . . . . . . . . . . .  10
       4.4.5.  The Extended IS Neighbors TLV . . . . . . . . . . . .  11
       4.4.6.  The MT Intermediate Systems TLV . . . . . . . . . . .  11
       4.4.7.  Reachability TLVs . . . . . . . . . . . . . . . . . .  11
       4.4.8.  The Router Capability TLV . . . . . . . . . . . . . .  12
       4.4.9.  The Multi-Topology TLV  . . . . . . . . . . . . . . .  12
       4.4.10. The SID/Label Binding and The Multi-Topology
               SID/Label Binding SID TLV . . . . . . . . . . . . . .  13
       4.4.11. The Area Segment SID TLV  . . . . . . . . . . . . . .  13
         4.4.11.1.  Flags  . . . . . . . . . . . . . . . . . . . . .  13
       4.4.12. The SRv6 Locator TLV  . . . . . . . . . . . . . . . .  14
       4.4.13. Traffic Engineering Information . . . . . . . . . . .  14
   5.  Inside Edge Router Functions  . . . . . . . . . . . . . . . .  14
     5.1.  Generating L2 IIHs to Outside Routers . . . . . . . . . .  14
     5.2.  Filtering LSP information . . . . . . . . . . . . . . . .  15
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  15
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