Bob, MBGP should be totally invisible to you, on a lab LAN inside
the ANL network, other than that you will see a new protocol returned
on mtrace, with the message "Unknown protocol code 8", which means
an MBGP router/route was used. [Once all the unexpected problems
at the border are resolved.]
MBGP is a part of BGP, RFC2283, "Multiprotocol Extensions for BGP-4".
This extension allows the exchange of routes to be used for multicast
forwarding, to take place at exchange points (where you would be
running BGP). Cisco treats these routes pretty much like any other
type of route, except that unicast forwarding ignores them if
they are the NLRI type "multicast [only] forwarding". The
routes can be carried on routers internal to an AS if needed,
but, normally, this would be the transit part of the network,
which connect different border routers, not the stub LAN parts.
That is, the routes are used very similarly to the way native PIM
uses DVMRP routes now. The big improvement there is using BGP,
and integrating multicast routing in the existing BGP policy-driven
routing structure, instead of the flat (potentially a route for
every subnet) DVMRP routing method. It is a large improvement
over the separate tunneled DVMRP mrouted cloud, which puts thousands
of user-managed workstations in the routing business.
In other words, inside the ANL network where you are already
running PIM anyway, you shouldn't ever see those MBGP routes.
LAN routers which may have been carrying DVMRP routes for PIM
will drop the DVMRP routes and will use the unicast routing table
to reach the border routers where unicast and multicast routes
differ. Those border or transit routers will use the MBGP
routes for PIM multicast forwarding. Only border and transit
routers where unicast and multicast routes differ need to know
about the MBGP routes.
Regards,
Hugh LaMaster
-- Hugh LaMaster, M/S 233-21, ASCII Email: lamaster@george.arc.nasa.gov NASA Ames Research Center Or: hlamaster@arc.nasa.gov Moffett Field, CA 94035-1000 No Junkmail: USC 18 section 2701 Phone: 650/604-1056 Disclaimer: Unofficial, personal *opinion*.