[Xorp-users] Cand-RP is ignored

Pavlin Radoslavov pavlin at icir.org
Wed May 24 11:59:07 PDT 2006


> On Wed, May 24, 2006 at 09:11:43AM +0200, Carsten Otto wrote:
> > Is it this packet?
> > [...]
> > I do not see any reaction to that.
> 
> I tested the scenario with another Xorp machine (in another network) and
> noticed that the following packet is being sent:
> 
> 14:52:58.531991 IP (tos 0x0, ttl  64, id 2787, offset 0, flags [none], proto 103, length: 42) fw-kullenhof.rz.rwth-aachen.de > mr-frankfurt2.x-win.dfn.de: PIMv2, length: 22
>     Candidate RP Advertisement (8) prefix-cnt=1 prio=0 holdtime=2m30s RP=fw-kullenhof.rz.rwth-aachen.de Group0=239.255.255.255
> 
> mr-frankfurt... is the BSR, 239.255.255.255/32 is the group for the Cand-RP and fw-kullenhof... is the machine running Xorp.
> 
> The local machine, which has the problem, does not send this packet.

Yes, once the elected BSR is known, each Cand-RP must unicast a
PIM Cand-RP-Adv message to it. If your XORP router doesn't send such
Cand-RP-Adv message, you need to find-out why it doesn't send it.
As a starter, enable the PIM traceoptions, and look for log messages
that indicate a Bootstrap message has been received.
After it is received with the elected Bootstrap router, the XORP
router should unicast the PIM Cand-RP-Adv message to it.

The sending of the Cand-RP-Adv message happens inside
PimVif::pim_cand_rp_adv_send(), so you may want to add some
XLOG_INFO() there to print various info (BTW, don't use printf(),
because the message may not be displayed immediately).

Pavlin

P.S. One possible issue that comes to mind is the following:
There must be an elected BSR router for a group range that covers
your own multicast group. If the received BSR info doesn't cover
your multicast group, then no Cand-RP-Adv message will be send.



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