[c-nsp] igmp snooping inside 802.1q trunks

[Tim Stevenson]

At 03:57 PM 2/1/2006, Tim Stevenson submitted:
>Not sure what to conclude based on that information.
>
>Flooding will happen in a few cases that occur to me:
>* IGMP snooping disabled
>* the port is learned/configured as a mrouter port
>* no querier present in the vlan (you can get unpredictable behavior 
>here, snooping is not supported unless there is a querier)

On second thought, I can't really think of a flooding case here - the 
common case is flaky membership (join state not refreshed for example).

Tim


>* the group IP maps to a reserved range MAC (0100.5e00.00xx)
>* a new source starts sending & no group mac exists (need to install 
>a "source-only" entry - this flooding lasts a very short time)
>* a source-only entry is removed from the h/w but the source is 
>still sending (again, flooding for a very short time)
>
>The fact that the streams originate from any particular switch (with 
>or without the querier attached) should not make any difference that 
>I can think of unless it falls into the above categories.
>
>A TAC case is probably the quickest way to resolution here...
>
>Tim
>
>At 11:02 AM 2/1/2006, Vladimir Ivashchenko submitted:
>
>>I traced multicast streams that were being sent to trunks without
>>receivers and found that they were coming from a different switch than
>>the querier. Is flooding expected in such cases?
>>
>> > Are you seeing snooping entries for the MAC? 0100.5e40.00xx (sh mac-
>> > multi igmp) If so, what is the port mask? You are sure it is
>> > 239.192.0.x & not 239.128.0.x? The latter would map to a reserved
>> > range MAC, & we won't install a snooping mac entry for it, it will
>> > flood....
>> >
>> > Tim
>> >
>> > At 10:19 AM 1/31/2006, Vladimir Ivashchenko submitted:
>> >
>> > >239.192.0.x
>> > >
>> > >On Mon, 2006-01-30 at 13:40 -0800, Tim Stevenson wrote:
>> > > > What group(s) are you sending to?
>> > > >
>> > > > Tim
>> > > >
>> > > > At 01:28 PM 1/30/2006, Vladimir Ivashchenko murmered:
>> > > > > > > The problem is that 6500 seems to unconditionally forward
>> > > all multicast
>> > > > > > > traffic to all trunk ports even if there are no receivers
>> > > > > > > there. E.g. "show mac-address-table multicast" does not show
>> > > > > > > any entries for that port, however it still receives all
>> > > > > > > multicast traffic.
>> > > > > > >
>> > > > > > > Any ideas?
>> > > > > >
>> > > > > > The 6500 is going to forward multicast traffic to any routers it
>> >
>> > > > > > learns about. Does a "show multicast router" on the 6500 list
>> > > > > > all the trunk ports?
>> > > > >
>> > > > >I checked it (using IOS's sh ip igmp snooping mrouter), only one
>> > > > >port there as expected.
>> > > > >
>> > > > >--
>> > > > >Best Regards
>> > > > >Vladimir Ivashchenko
>> > > > >Chief Technology Officer
>> > > > >Thunderworx, Cyprus - www.thunderworx.com
>> > > > >_______________________________________________
>> > > > >cisco-nsp mailing list  cisco-nsp at puck.nether.net
>> > > > >https://puck.nether.net/mailman/listinfo/cisco-nsp
>> > > > >archive at http://puck.nether.net/pipermail/cisco-nsp/
>> > > >
>> > > >
>> > > >
>> > > > 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.
>> > >--
>> > >Best Regards,
>> > >Vladimir Ivashchenko
>> > >Chief Technology Officer
>> > >Thunderworx Cyprus - www.thunderworx.com
>> >
>> >
>> >
>> > 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.
>> > _______________________________________________
>> > cisco-nsp mailing list  cisco-nsp at puck.nether.net
>> > https://puck.nether.net/mailman/listinfo/cisco-nsp
>> > archive at http://puck.nether.net/pipermail/cisco-nsp/
>>--
>>Best Regards,
>>Vladimir Ivashchenko
>>Chief Technology Officer
>>Thunderworx Cyprus - www.thunderworx.com
>
>
>
>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.