IS-IS Extended Hierarchy
draft-ietf-lsr-isis-extended-hierarchy-03
Internet Engineering Task Force T. Li
Internet-Draft Arista Networks
Intended status: Standards Track L. Ginsberg
Expires: July 7, 2021 P. Wells
Cisco Systems
January 3, 2021
IS-IS Extended Hierarchy
draft-ietf-lsr-isis-extended-hierarchy-03
Abstract
The IS-IS routing protocol was originally defined with a two level
hierarchical structure. This was adequate for the networks at the
time. As we continue to expand the scale of our networks, it is
apparent that additional hierarchy would be a welcome degree of
flexibility in network design.
This document defines IS-IS Levels 3 through 8.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. PDU changes . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Circuit Type . . . . . . . . . . . . . . . . . . . . . . 4
2.2. PDU Type . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Additional PDUs . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Level n LAN IS to IS hello PDU (Ln-LAN-HELLO-PDU) . . . . 5
3.2. Level n Point-to-point IS to IS hello PDU (Ln-P2P-HELLO-
PDU) . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Level Specific Area Identifiers . . . . . . . . . . . . . . . 5
4.1. IS-IS Area Hierarchy TLV . . . . . . . . . . . . . . . . 6
4.2. Adjacency Formation Rules . . . . . . . . . . . . . . . . 8
4.2.1. Level 3-8 Adjacency Formation Rules . . . . . . . . . 8
4.2.2. Special Level-1 and Level-2 Adjacency Formation Rules 9
4.2.2.1. Actions on a Point-to-Point Circuit . . . . . . . 9
4.2.2.2. Actions on a LAN Circuit . . . . . . . . . . . . 9
4.2.2.3. Reporting of Mismatched Area Hierarchies . . . . 9
5. New Flooding Scopes . . . . . . . . . . . . . . . . . . . . . 10
6. MAC Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
7. Inheritance of TLVs . . . . . . . . . . . . . . . . . . . . . 13
8. Behavior of Level n . . . . . . . . . . . . . . . . . . . . . 13
9. Relationship between levels . . . . . . . . . . . . . . . . . 13
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
11.1. PDU Type . . . . . . . . . . . . . . . . . . . . . . . . 13
11.2. New PDUs . . . . . . . . . . . . . . . . . . . . . . . . 13
11.3. New TLVs . . . . . . . . . . . . . . . . . . . . . . . . 14
11.4. New Flooding Scopes . . . . . . . . . . . . . . . . . . 14
11.5. New MAC Addresses . . . . . . . . . . . . . . . . . . . 15
12. Security Considerations . . . . . . . . . . . . . . . . . . . 16
13. Normative References . . . . . . . . . . . . . . . . . . . . 16
Appendix A. Preventing Cross Branching in the Hierarchy . . . . 16
Appendix B. Guidelines for Introducing a new level . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction
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