Updates to the IS-IS TLV Codepoints Registry
updated by
- rfc-9352 — IS-IS Extensions to Support Segment Routing over the IPv6 Data Plane
Extracted elements (10)
Early codepoint allocation for I-Ds before they progress to RFC is advantageous (as described in RFC 7120), but RFC 7120's early-allocation procedures do not apply to 'Expert Review' registries like the IS-IS TLV Codepoints registry. Instead, Designated Expert guidance is used to achieve the same goal within the Expert Review framework.
The consolidation of separate prefix reachability sub-TLV registries for TLVs 135, 235, 236, and 237 into a single registry represents no change to the IS-IS protocol itself — only a clearer representation of the intended sub-TLV allocation strategy, since existing sub-TLV assignments were already common to all four TLVs.
Application for a codepoint allocation MAY be made to the Designated Experts at any time, without waiting for the associated I-D to progress to RFC.
Designated Experts SHOULD only consider codepoint allocation requests arising from I-Ds that have already been accepted as Working Group documents or are planned for progression as AD Sponsored documents in the absence of a suitably chartered Working Group.
Designated Experts SHOULD review allocation requests on their technical merit and SHOULD NOT seek to overrule IETF consensus, but MAY raise issues for further consideration before assignments are made.
For Working Group documents, Designated Experts SHOULD check with Working Group chairs that there is consensus within the Working Group to make the allocation at that time. For AD Sponsored documents, they SHOULD check with the AD for approval.
If a document that received early codepoint allocation fails to progress to RFC, the expiry and deallocation process defined in RFC 7120 MUST be followed for the relevant codepoints, with Designated Experts performing the role assigned to Working Group chairs.
Four previously separate prefix reachability sub-TLV registries (for TLVs 135, 235, 236, and 237) have been consolidated into a single registry entitled 'Sub-TLVs for TLVs 135, 235, 236, and 237'. The existing sub-TLV assignments (types 1 and 2 administrative tag sub-TLVs from RFC 5130) apply to all four TLVs.
The IS Neighbor sub-TLV registry, previously named 'Sub-TLVs for TLVs 22, 141, and 222', has been extended to include TLVs 23 (IS Neighbor Attribute TLV) and 223 (MT IS Neighbor Attribute TLV) defined in RFC 5311, and renamed 'Sub-TLVs for TLVs 22, 23, 141, 222, and 223'. Settings for each sub-TLV mirror those for TLVs 22 and 222 respectively.
This document introduces no new security issues. The changes are editorial and administrative, affecting only IANA registry structure and Designated Expert guidance.