[c-nsp] Multicast Issue

Wed Apr 26 19:14:41 EDT 2006

I think you're right that the problem is at L2. The 6513 is connected
via trunk port to a 2950. I have IGMP snooping disabled on the 2950 and
another static MAC address entry pointing to the interface where the
server is connected. It sure seems like it should work, darn it!  :)

Regarding snooping on Vlan4, I didn't disable it globally but I did
disable for that MAC address using the disable-snooping keyword in the
mac-address-table command.

Thanks!
John
--

>>> Tim Stevenson <tstevens at cisco.com> 4/26/06 5:05:11 PM >>>
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.