Transport

Transport routes packets across the mesh: it discovers paths, forwards packets toward known next hops, and propagates announces. The wire surfaces (path request and path response packets) are normative and proven by [VEC-PATH-REQUEST]. The routing internals (tables, retransmission timing, deduplication, TTLs) are informative.

Path request

To discover a path, a node sends a path request: a DATA packet to the PLAIN destination rnstransport.path.request (Transport.request_path, Transport.py:2786-2787). The payload is (Transport.py:2783-2784):

target_destination_hash(16) || [transport_identity_hash(16)] || request_tag

The transport_identity_hash is included only when transport is enabled on the requesting node; the request_tag is a random hash that deduplicates the request (Transport.py:2780). [VEC-PATH-REQUEST] is a frozen-injection vector with transport disabled: payload target(16) || tag(16), in a PLAIN HEADER_1 packet (flags 08). An implementation MUST address the request to this PLAIN destination and use this payload order so existing nodes answer it.

Path response

A node that holds a path answers by re-emitting the destination’s cached announce with the packet context set to PATH_RESPONSE (0x0B) instead of NONE (Transport.py:2943-2972). The announce data is byte-identical to an ordinary announce (see Announce); only the context differs, and the rebroadcast is marked so it is not propagated further.

Routing internals (informative)

The following are reference behaviour an implementation MAY diverge from:

• Tables. Transport maintains path, announce, reverse, link, and tunnel tables, each a list indexed by the IDX_* constants (Transport.py:3547-3586). A path entry holds timestamp, next hop, hops, expiry, the announce random blobs, the receiving interface, and the cached packet hash.
• Announce propagation. Announces are rebroadcast with a hop limit PATHFINDER_M = 128, up to LOCAL_REBROADCASTS_MAX = 2 local rebroadcasts, after a grace PATHFINDER_G = 5 s plus random jitter PATHFINDER_RW = 0.5 s (Transport.py:63-77).
• Path TTLs. Default PATHFINDER_E = 7 days; access-point paths AP_PATH_TIME = 1 day; roaming paths ROAMING_PATH_TIME = 6 hours (Transport.py:71-73).
• Deduplication. A rolling table of recent packet hashes suppresses loops.
• Path request pacing. PATH_REQUEST_TIMEOUT = 15 s, PATH_REQUEST_MI = 20 s minimum interval, and per-interface announce caps (Transport.py:79-83).

These values and structures are documented for fidelity; only the path request and path response packets above are normative.