[Xorp-users] Fwd: underlying vif is not UP

Pavlin Radoslavov pavlin at icir.org
Fri Oct 20 13:13:02 PDT 2006

> For the multicast forwarding, I still have a slight problem, my network
> looks like this:
> Content server <-------->multicast enabled router (xorp) <-------->
> destination
> I have network analyzers on both the server and the destination, I was able
> to see PIM-SM hello messages on the destination machine but there is no
> reply.

What do you mean by "there is no reply". The PIM Hello messages are
just send periodically on each interface, and in PIM-SM there are no
reply messages or anything like this.

> Basically I was configuring the rp statically, but ten changed it to
> candidate BSR/candidate RP option, nothing changed.
> I thought that it is because I ahve one router only, the routing is not
> successful, I am trying to configure another router and add it between the
> content server and the destination so that I  have 2 enabled routers in
> between.

If you have a single PIM-SM router, then the simplest setup is to
configure it as a static RP (as you probably have tried already).
In addition to PIM-SM you need to have mfea, igmp, and fib2mrib
configured as well. Also, make sure that your kernel has multicast
forwarding enabled. The XORP User Manual has information about this
for eash supported OS (Section 13.3.1).

If everything is configed correctly, you should see the static RP by
using the "show pim rps" xorpsh command.
The "show igmp group" command should show the multicast group
membership on each interface.
The "show pim join" command should show you the PIM-SM multicast
routing entries.
The "show pim mfc" command should show the multicast forwarding

If the IGMP and PIM-SM state is correct, but you still don't see
multicast traffic being forwarded, make sure that the sender's TTL
of the multicast packets is > 1.

> Now, honestly the idea of the candidate BSR/candidate RP is not obvious for
> me. Any body has informaton on that? and where might be the problem??

The CandBSR/CandRP mechanism is used for dynamically distributing
the RP Set information across a PIM-SM domain. In your setup it will
be simpler to use a static RP.


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