[c-nsp] Multicast Issue

Wed Apr 26 19:05:11 EDT 2006

I assume you never disabled snooping in vlan 4? Multicast router 
ports (in this case the internal router, the RP/MSFC) are always 
member ports for all snooping groups.

This all looks ok.

Can you do a sh mls ip multicast and see if the packet stats increase 
for this S,G - if they do (& I think they will/should), then the 
packets are getting to vlan 1 & then you need to focus your 
troubleshooting on L2 between vlan 1 & the server.

Tim

At 03:58 PM 4/26/2006, John Neiberger pronounced:
>This is on a native mode SUP2.
>
>I just had my co-worker startup the client and I see this:
>
>(10.a.b.c, 224.0.1.55), 00:07:16/00:00:10, flags: T
>   Incoming interface: Vlan4, RPF nbr 0.0.0.0, RPF-MFD
>   Outgoing interface list:
>     Vlan1, Forward/Dense, 00:07:16/00:00:00, H
>
>where 10.a.b.c is the IP address of the client.
>
>Here is the output of some debugging:
>
>y19w: IP: s=10.a.b.c (Vlan4) d=224.0.1.55 (Vlan1) len 92, mforward
>1y19w: MRT: Create (10.a.b.c,224.0.1.55), RPF Vlan4/0.0.0.0
>1y19w: MRT: WAVL Insert interface: Vlan1 in (10.a.b.c,224.0.1.55)
>Successful
>1y19w: MRT: Add Vlan1/224.0.1.55 to the olist of (10.a.b.c,
>224.0.1.55), Forward state
>1y19w: IP: MAC sa=0003.470b.6bce (Vlan4), IP last-hop=10.a.b.c
>1y19w: IP: IP tos=0x0, len=78, id=0x34BF, ttl=1, prot=17
>1y19w: IP: s=10.a.b.c (Vlan4) d=224.0.1.55 (Vlan1) len 92, mforward
>
>Interestingly, the output of show mac-address-table multicast shows two
>entries for 0100.5e00.0137:
>
>4  0100.5e00.0137    static  Yes   --  Router
>1  0100.5e00.0137    static  Yes   --  Gi4/16
>
>The Vlan1 entry is my static entry. Why would the 6513 an entry in
>Vlan4? The source of the packet is in Vlan4 but I don't understand why
>that would create an entry in the mac address table. Isn't the table
>only for destination MAC addresses? If so, why would an entry show up
>for the source?
>
>Thanks!
>John
>--
>
>
> >>> Tim Stevenson <tstevens at cisco.com> 4/26/06 4:44:38 PM >>>
>Do you see a source,group entry? You seem to be running dense mode,
>and DM fwding is always on the s,g never the *,g (the *,g is created
>but not used for fwding).
>
>So you need to see a PC,224.0.1.55 mroute entry with vlan1 as an OIF.
>
>BTW, what supervisor engine are you using, sup2 or sup720?
>
>Also, you are sure the packets are not getting L3 switched (ie, that
>they're not dropping somewhere in vlan 1)?
>
>Tim
>
>At 02:37 PM 4/26/2006, John Neiberger pronounced:
> >I've got an interesting issue that I think I'm tantalizingly close to
> >solving but I haven't had to deal with multicast stuff in years.
> >
> >We have a PC on one subnet that is sourcing a multicast packet. I
>need
> >to get that packet to a device on another LAN that is not capable of
> >sending IGMP joins. Here's the topology:
> >
> >PC *- 6513(IOS) *- 2950 *- Server
> >
> >In this case, the PC is sending out a single multicast packet trying
>to
> >reach the server. The packet does not reach the server because it
>can't
> >join the group. The multicast group is 224.0.1.55. The "server" is in
> >Vlan1, so on the 6513 I have the following configured:
> >
> >int Vlan1
> >  ...
> >  ip igmp static-group 224.0.1.55
> >!
> >! That makes Vlan1 show up in the mroute table, but I still need to
> >forward that packet out some particular interface, right? So...
> >!
> >mac-address-table static 0100.5e00.0137 vlan 1 interface
> >GigabitEthernet4/16
> >!
> >!  That statically forwards traffic destined for that multicast
>address
> >out the interface leading to the Catalyst 2950
> >
> >On the 2950 I have the following:
> >
> >mac-address-table static 0100.5e00.0137 vlan 1 interface
> >GigabitEthernet0/2
> >
> >That should forward the multicast traffic to the server hanging of
>off
> >g0/2. However, this isn't working. I've tinkered with a couple of
> >different configs but nothing seems to work. Debugging shows that the
> >multicast packet is making it to the 6513.
> >
> >1y19w: IP: s=10.a.b.c (Vlan4) d=224.0.1.55 (Vlan1) len 92, mforward
> >
> >The output of "show ip mroute 224.0.1.55" shows the following:
> >
> >(*, 224.0.1.55), 00:00:01/00:02:58, RP 0.0.0.0, flags: DC
> >   Incoming interface: Null, RPF nbr 0.0.0.0
> >   Outgoing interface list:
> >     Vlan1, Forward/Dense, 00:00:01/00:00:00
> >
> >It looks to me like the 6513 should know where to forward the packets
> >but it isn't working.
> >
> >Any ideas?
> >
> >Thanks!
> >John
> >--
> >_______________________________________________
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>
>
>
>Tim Stevenson, tstevens at cisco.com
>Routing & Switching CCIE #5561
>Technical Marketing Engineer, Catalyst 6500
>Cisco Systems, http://www.cisco.com
>IP Phone: 408-526-6759
>********************************************************
>The contents of this message may be *Cisco Confidential*
>and are intended for the specified recipients only.

Tim Stevenson, tstevens at cisco.com
Routing & Switching CCIE #5561
Technical Marketing Engineer, Catalyst 6500
Cisco Systems, http://www.cisco.com
IP Phone: 408-526-6759
********************************************************
The contents of this message may be *Cisco Confidential*
and are intended for the specified recipients only.