From: ccie2be (ccie2be@nyc.rr.com)
Date: Mon Dec 20 2004 - 16:22:05 GMT-3
As I recall, the 3550 doesn't support cgmp - at least not in the same way
that Cat 5000's do. Therefore, to restrict mcast traffic to just the ports
that require that traffic, the 3550 has to use igmp snooping.
----- Original Message -----
From: "McLaughlin, Jeffery" <JMcLaughlin@sfchronicle.com>
To: "Sheahan, John" <John.Sheahan@priceline.com>; <ccielab@groupstudy.com>
Sent: Monday, December 20, 2004 12:52 PM
Subject: RE: When should use IGMP SNOOPING on 3550?
> 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.
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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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