From: McLaughlin, Jeffery (JMcLaughlin@sfchronicle.com)
Date: Mon Dec 20 2004 - 14:52:39 GMT-3
Keep in mind that if the switch doesn't know on which ports multicast group
members reside, it has to flood the multicast traffic out every port. One way
for the switch to know is to use CGMP, where the router (which is keeping
track of where IGMP members are) explicitly tells the switch which multicast
clients. Another option is for the switch to look inside IGMP packets to
determine where multicast group members are. Knowing where multicast group
members are prevents the switch from having to flood out every port.
Jeff McLaughlin
CCIE #14023
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Sheahan, John
Sent: Monday, December 20, 2004 9:40 AM
To: Brian McGahan; ben; ccielab@groupstudy.com
Subject: RE: When should use IGMP SNOOPING on 3550?
I guess I don't understand why the switch needs to know..I thought the
router took care of IGMP joins etc..?
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Brian McGahan
Sent: Monday, December 20, 2004 11:28 AM
To: ben; ccielab@groupstudy.com
Subject: RE: When should use IGMP SNOOPING on 3550?
Ben,
IGMP snooping is used on layer 2 switchports to determine of a
client located on that port has joined a multicast group. This behavior
is enabled by default. To view what information is learned via snooping
issue the "show ip igmp snooping group" command.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
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> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> ben
> Sent: Sunday, December 19, 2004 9:46 PM
> To: ccielab@groupstudy.com
> Subject: When should use IGMP SNOOPING on 3550?
>
> In some Multicast cases, it's work that just enable the PIM on the
> according interface, and configure the appropriate multicast mode, in
> these cases, It doesn't to enable the IGMP snooping on the 3550
switch, So
> I am wondering when should use the IGMP snooping on the switch?
>
> Thanks
>
>
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