Area Proxy for IS-IS
draft-li-lsr-isis-area-proxy-00
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2019-10-03
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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: 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
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 5, 2020.
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
(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
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
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
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