[Xorp-users] Multicast without PIM on internal interface while PIM on external

[Pavlin Radoslavov]

> > It is normal to receive NOCACHE signal with src that is not directly
> > connected, because NOCACHE is triggered when the multicast
> > forwarding plane sees a multicast data packet (eventually from a
> > sender several hops away) and the forwarding plane doesn't have a
> > matching forwarding entry for that packet.
> 
> 	Well. And what about directly connected src ? I'm sure the NOCACHE is 
> generated for directly connected sources also (see log bellow). If it's 

It is normal to receive NOCACHE for sources regardless whether they
are directly connected or not.
In any case, the interface the packet was received on must be
enabled in the MFEA configuration section.

One thing you were probably seeing is that in the MFEA section you
enabled the interface toward the source, but you disabled it in the
PIM section: the MFEA received the NOCACHE upcall and accepted it,
but then PIM (correctly) threw it away.

Pavlin


> not kernel bug it explain why I have problem with my original 
> configuration. There has been PIM disabled on vif_index=2 because there 
> has been no other mrouter on the wire. When packet has been sent from 
> 195.113.24.3 to 224.0.1.22 the kernel generate NOCACHE with vif_index=2 
> which has been dropped due (! pim_vif->is_up())
> 
> 	I'm not sure about exact interpretation of the PIM specification. It 
> seems to be pretty correct to drop the signal when source is not 
> directly connected as we need PIM on the interface which is disabled. On 
> the other side, when source is directly connected, then processing can 
> be done with no PIM communication on the interface from the triggering 
> packet come. There seems not to be reason to deny NOCACHE message 
> because interface is not PIM enabled - just because the PIM over 
> disabled interface is not necesarry to process the signal. It's true ? 
> Miss I'm somethink ?
> 
> 
> 						Dan
> 
> 
> 
> [ 2005/06/16 03:09:19 TRACE xorp_fea MFEA ] RX kernel signal: 
> message_type = 1 vif_index = 2 src = 195.113.24.3 dst = 224.0.1.22
> [ 2005/06/16 03:09:19 TRACE xorp_pimsm4 PIM ] RX NOCACHE signal from 
> MFEA_4: vif_index = 2 src = 195.113.24.3 dst = 224.0.1.22
> [ 2005/06/16 03:09:19 TRACE xorp_pimsm4 PIM ] src = 195.113.24.3 is 
> directly connected
> [ 2005/06/16 03:09:19 TRACE xorp_pimsm4 PIM ] install a MFC in the kernel
> [ 2005/06/16 03:09:19 TRACE xorp_pimsm4 PIM ] Add MFC entry: 
> (195.113.24.3,224.0.1.22) iif = 2 olist = ...O
> ....
> ....
> ....
> [ 2005/06/16 03:12:52 TRACE xorp_fea MFEA ] RX kernel signal: 
> message_type = 4 vif_index = 0 src = 0.0.0.0 dst = 0.0.0.0
> [ 2005/06/16 03:12:52 TRACE xorp_fea MFEA ] RX dataflow message: src = 
> 195.113.24.3 dst = 224.0.1.22
> [ 2005/06/16 03:12:52 TRACE xorp_pimsm4 PIM ] RX DATAFLOW signal: source 
> = 195.113.24.3 group = 224.0.1.22 threshold_interval_sec = 210 
> threshold_interval_usec = 0 measured_interval_sec = 210 
> measured_interval_usec = 790337 threshold_packets = 0 threshold_bytes = 
> 0 measured_packets = 0 measured_bytes = 0 is_threshold_in_packets = 1 
> is_threshold_in_bytes = 0 is_geq_upcall = 0 is_leq_upcall = 1
> [ 2005/06/16 03:12:52 TRACE xorp_pimsm4 PIM ] Delete MFC entry: 
> (195.113.24.3,224.0.1.22) iif = 2 olist = ...O
> 
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