moq-relay-hops: carry HOP_PATH on NAMESPACE via an extended Parameters field

[kixelated]

Problem

The Relay Hops extension relies on namespace advertisements carrying a HOP_PATH parameter as they propagate through a relay mesh. But in the subscriber-driven flow, advertisements propagate downstream as NAMESPACE messages (moqt Section 10.16) — the response to SUBSCRIBE_NAMESPACE — and that message has no Parameters field (only Type, Length, Track Namespace Suffix). So HOP_PATH had nowhere to ride on the reactive path, which is exactly the relay-mesh scenario the extension targets.

PUBLISH_NAMESPACE (0x6) and SUBSCRIBE_NAMESPACE (0x50) do carry a Parameters field, so HOP_PATH on the former and EXCLUDE_HOP on the latter were already fine.

Fix

This extension now defines an extended NAMESPACE message that appends Number of Parameters + Parameters after the (self-delimiting) Track Namespace Suffix, used only on a session that negotiated Relay Hops. HOP_PATH is carried there as well as on PUBLISH_NAMESPACE.

• New section "Carrying Parameters on Namespace Advertisements" defining the extended NAMESPACE wire format (NAMESPACE_DONE is explicitly not extended — no state to carry).
• Introduction describes both advertisement paths (proactive PUBLISH_NAMESPACE and reactive NAMESPACE responses).
• Setup Negotiation ties the extended NAMESPACE format to the RELAY_HOPS negotiation; relays include HOP_PATH on every PUBLISH_NAMESPACE and NAMESPACE. Graceful-degradation wording updated since a non-negotiating session omits the whole Parameters field on NAMESPACE.
• HOP_PATH Parameter now carried in PUBLISH_NAMESPACE or an extended NAMESPACE.
• IANA HOP_PATH "Carried In" updated to PUBLISH_NAMESPACE, NAMESPACE.

EXCLUDE_HOP needed no change.

Extending a base-protocol message's wire format from an extension is safe here because it is gated on the per-session SETUP negotiation — both endpoints agree on whether NAMESPACE carries the trailing Parameters field before any NAMESPACE is sent.

Draft builds cleanly (kramdown-rfc ... OK, xml2rfc-txt ... OK).

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Review failed

The pull request is closed.

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 746a576 and 6a30a1d.

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• draft-lcurley-moq-relay-hops.md

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Walkthrough

This change updates the draft-lcurley-moq-relay-hops.md specification. It clarifies that both PUBLISH_NAMESPACE and NAMESPACE messages are treated as namespace advertisements, expands Setup Negotiation rules so negotiated sessions must carry HOP_PATH on both message types and honor EXCLUDE_HOP, and introduces a new section defining an extended NAMESPACE message format with an appended Parameters field. The MOQT Message Parameters registration table is updated to reflect where HOP_PATH and EXCLUDE_HOP are carried.

Changes

Area	Description
Introduction	Explicitly lists PUBLISH_NAMESPACE and NAMESPACE as namespace advertisements
Setup Negotiation	Requires HOP_PATH on negotiated sessions for both message types; requires honoring EXCLUDE_HOP; specifies behavior when not negotiated
New section	Defines extended NAMESPACE message format with appended Parameters field and parsing rules bounded by Length
Registration table	Updates carried-in locations for HOP_PATH and EXCLUDE_HOP parameters

Related issues: None specified.

Related PRs: None specified.

Suggested labels: documentation, spec-change

Suggested reviewers: lcurley

Poem

A rabbit hops through session's gate,
With HOP_PATH tags to navigate,
NAMESPACE grows a new extension,
Parameters carried with intention,
EXCLUDE_HOP whispers, "not this way,"
The draft evolves another day. 🐇📜

✨ Finishing Touches

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch claude/distracted-gagarin-9f2d98

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