[c-nsp] Multicast on a 6500 running ios

Mon Jan 29 14:17:38 EST 2007

We don't flood traffic when snooping is enabled. If the hosts 
religiously send unsolicited reports at an interval less than ~180 
seconds (3 default query intervals), then the traffic will flow 
uninterrupted. My experience is that most hosts don't behave that way 
- to remove all doubt, add a querier to the vlan.

Tim

At 02:02 PM 1/29/2007 -0500, Todd, Douglas M. averred:
>All:
>
>We had problems with the 6500's and multicast. It seems that the 6500 will not
>pass certain multicast frames with out using the "igmp snooping querier"
>fuction.  With out this command mcast packets are silently 
>droped.  This was the
>resolution to a Multitech problem (which uses L2 multicast) where 
>devices on the
>same switch could not communicate propperly.
>
>Just some food for thought.
>
>DMT
>
>-----Original Message-----
>From: cisco-nsp-bounces at puck.nether.net
>[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Tim Stevenson
>Sent: Monday, January 29, 2007 1:32 PM
>To: Dale W. Carder
>Cc: cisco-nsp
>Subject: Re: [c-nsp] Multicast on a 6500 running ios
>
>Yes, it will work, I use it for L2 multicast testing in my lab all the time.
>
>You can see here that the switch is learned as an "mrouter" even tho 
>the SVI is
>shut. Note the debug msg as well.
>
>tstevens-6509-neb-2#sh run int vl 55
>Load for five secs: 1%/0%; one minute: 3%; five minutes: 3% Time 
>source is NTP,
>10:25:47.041 PST Mon Jan 29 2007
>
>Building configuration...
>
>Current configuration : 97 bytes
>!
>interface Vlan55
>   ip address 10.55.55.1 255.255.255.0
>   ip igmp snooping querier
>   shutdown
>end
>
>tstevens-6509-neb-2#sh ip igmp snoo mrou Load for five secs: 1%/0%; 
>one minute:
>3%; five minutes: 3% Time source is NTP, 10:25:48.617 PST Mon Jan 29 2007
>
>vlan            ports
>-----+----------------------------------------
>    55  Switch
>tstevens-6509-neb-2#
>Jan 29 10:27:08.957: SP: TX IGMP QUERY from: 10.55.55.1 to: 224.0.0.1
>group: 0.0.0.0 vlan: 55 ltl: 8A8
>
>
>
>Here's the same vlan 55 interface but w/PIM & no shut:
>
>tstevens-6509-neb-2#sh run int vl 55
>Load for five secs: 1%/0%; one minute: 4%; five minutes: 2%
>Time source is NTP, 10:30:57.625 PST Mon Jan 29 2007
>
>Building configuration...
>
>Current configuration : 81 bytes
>!
>interface Vlan55
>   ip address 10.55.55.1 255.255.255.0
>   ip pim sparse-mode
>end
>
>tstevens-6509-neb-2#sh ip igmp snoo mrou
>Load for five secs: 1%/0%; one minute: 4%; five minutes: 2%
>Time source is NTP, 10:30:58.665 PST Mon Jan 29 2007
>
>vlan            ports
>-----+----------------------------------------
>    55  Router
>tstevens-6509-neb-2#
>
>
>Thanks,
>Tim
>
>At 12:01 PM 1/29/2007 -0600, Dale W. Carder averred:
>
> >On Jan 29, 2007, at 11:31 AM, Tim Stevenson wrote:
> >>
> >>In any case, you can use snooping querier by configuring an SVI with
> >>the querier & an IP address, but leaving the interface in the "shut"
> >>state, preventing any L3 switching happening on that VLAN. The
> >>querier will still work in this case.
> >
> >Really?!  We had asked the TAC if something like that would work,
> >but they didn't think so.
> >
> >We are seeing issues in the data center where more H/A solutions want
> >multicast between the hosts (through multiple switches), but there
> >couldn't be any routing out of that vlan.  This would be perfect.
> >
> >Dale
> >
> >----------------------------------
> >Dale W. Carder - Network Engineer
> >University of Wisconsin at Madison
> >http://net.doit.wisc.edu/~dwcarder
>
>
>
>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
>********************************************************
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>and are intended for the specified recipients only.
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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.