RFC 9377: IS-IS Flood Reflection
In plain English — editorial summary, not part of the RFC
This document describes a backward-compatible, optional IS-IS extension that allows the creation of IS-IS flood reflection topologies. Flood reflection permits topologies in which IS-IS Level 1 (L1) areas provide transit-forwarding for IS-IS Level 2 (L2) areas using all available L1 nodes internally. It accomplishes this by creating L2 flood reflection adjacencies within each L1 area. Those adjacencies are used to flood L2 Link State Protocol Data Units (LSPs) and are used in the L2 Shortest Path First (SPF) computation. However, they are not ordinarily utilized for forwarding within the flood reflection cluster. This arrangement gives the L2 topology significantly better scaling properties than prevalently used flat designs. As an additional benefit, only those routers directly participating in flood reflection are required to support the feature. This allows for incremental deployment of scalable L1 transit areas in an existing, previously flat network design, without the necessity of upgrading all routers in the network.
Document record
- Document ID
- RFC9377
- Published
- April 2023
- Authors
- T. Przygienda; C. Bowers; Y. Lee; A. Sharma; R. White
- Status
- EXPERIMENTAL
- Stream
- IETF
- Area
- rtg
- Pages
- 19
- Also known as
- —
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The document record above — title, authors, date, status, stream, area, relationships, DOI and errata — is imported verbatim from the public RFC Editor index. The “in plain English” section is editorial: written by The metasystema editorial team, not part of the RFC. Where the two differ, the RFC text governs.
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