Description: The bits of tBgpInstanceTransportTunnel specify whether VPNs can exchange routes across autonomous system boundaries, providing model B connectivity. The 'no' form of the command disallows ASBRs to advertise VPRN routes to their peers in other autonomous systems. If a bit is set, the corresponding mechanism will be used to exchange routes.

The mechanisms represented by each bit are: ldp(0) - This allows LDP based LSPS to be used as transport from the ASBR to local PE routers rsvp-te(1) - This allows RSVP-TE based LSPS to be used as transport from the ASBR tolocal PE routers mpls(2) - This allows both LDP and RSVP-TE to be used to resolve the BGP nexthop for VPRN routes in an associated VPRN instance.