[Xorp-users] join messages not sent out (from IGMP to PIM)

[Pavlin Radoslavov]

> I have a router running xorp and am trying to receive stream on the
> local net from an external RP.
> 
> "show igmp group" does show me the clients as having joined the group.
> But it does not register with the RP then.
> 
> "show pim join all"
> Group           Source          RP              Flags
> 224.0.0.0       xxx.xxx.xxx.xxx xxx.xxx.xxx.xxx RP
>     Upstream interface (RP):   eth1
>     Upstream MRIB next hop (RP): xxx.xxx.xx.xxx
>     Upstream state:            NotJoined
>     Join timer:                -1
>     Joins RP:                  ...
>     Join state:                ...
>     Prune state:               ...
>     Prune pending state:       ...
>     Could assert WC:           ...
>     I am DR:                   OOO
>     Immediate olist RP:        ...
>     Inherited olist SG:        ...
>     Inherited olist SG_RPT:    ...

If this is the only entry in the multicast routing table, then it
appears that you don't have any (*,G) entry for your multicast
group. This would explain why you don't see PIM Join messages
originated by XORP.

Can you double-check that the multicast group is not link-local
(i.e., it shouldn't be in the range 224.0.0.0 -- 224.0.0.255), and
that it indeed is shown by "show igmp group".
If the IGMP module sees the group membership, then it is the one to
tell PIM about it. If you have enabled the PIM log messages, do you
see a PIM log message like "Add membership for (%s, %s) on vif %s"
when the first receiver joins the group?

> So xorp does not seem to be sending out join messages via pim.
> When enabling all traces, I can see the IGMP join and I can see
> PIM_HELLOs from the RP. I cann not see it sending out join messages via pim.
> 
> I am using the example config from the website mainly. I have tried
> configuring the RP statically, but with the same result. Anyhow the RP
> seems to be recognized correctly. Scope is fine, so is the next hop.
> 
> What could be the causing problem?
> 
> Do I have to configure igmp on the local vif only or on both?

Typically you should configure IGMP on all interfaces that are
running PIM (the special register_vif is an exception).

> How about pim, do I need to activate that on the external vif only or on
> both?

You should configure PIM on all interfaces that are expected to be
used in the forwarding process: all potential incoming interfaces
and all potential outgoing interfaces.

Pavlin