Summary

  • The 2 November MUP architecture revision 03 makes session-to-route transformation and route resolution normative, but assigns the BGP-MUP SAFI, NLRI and extended-community encoding to a separate BESS draft.
  • In the architecture's home-routed roaming example, a session-specific ST2 route wins by longest match over a broader VPN route. Import policy and segment-community identity decide which operator's network that session can reach.

The older July draft said MUP needed routing-protocol extensions. The November draft names the division of labour. Its own rules cover MUP segments, discovery routes, session-transformed routes and the behaviour required of a controller and provider-edge router. It expressly leaves wire encoding and IANA requests to the BESS BGP-MUP SAFI work. A route therefore has two sets of instructions: what the mobile session means and which bytes another BGP speaker receives.

That division is concrete inside a network. A MUP controller receives the device prefix and tunnel endpoint identifiers from the mobile system. It turns that session data into routing information. An ST1 route gives reachability toward the user's prefix. An ST2 route matches a tunnel endpoint and is resolved against a Direct or Interwork Segment Discovery route. The edge router then installs forwarding state for the matched segment. The BESS draft supplies the BGP-MUP route types, NLRI and extended-community format needed to carry those instructions between speakers. Both texts remain working-group drafts, as their DMM and BESS records show.

The draft's home-routed roaming example gives the control boundary teeth. A session-specific ST2 route for tunnel endpoint Xa wins over the broader VPN route for prefix X/x by longest-prefix match. Only packets for that session take the MUP path. Interwork Segment communities keep two home operators' N9 networks separate even if their IP address space overlaps. The MUP security text requires authorised BGP peers and import/export policy that confines each route to intended routing instances and peers. Reusing a segment-community value while older ST routes still advertise it can steer mobile traffic to the wrong operator.

RFC 7333 asks distributed mobility management to avoid a distant single anchor where possible. This architecture offers a route-based mechanism for doing so, but its exact forwarding outcome belongs to the controller's session input, the BGP encoding, the operator's import policy and the edge router's resolution together. The official record contains no named interoperable implementation or forwarding trace across the two drafts; one such trace would show whether the handoff works in running software.