All things related to multicast

["Kevin C. Almeroth" <>]

From: "Wallace, Steven S" 
<>
To: "Tsegreda Beyene" 
<>,
        "Alan Crosswell" 
<>,
 
<>
Cc: 
<>

I defer to Tsege.  I have to say that this is VERY odd.  Turning off
IGMP snooping turns off ASIC forwarding?

ssw

-----Original Message-----
From: Tsegreda Beyene 
[mailto:]=20
Sent: Tuesday, November 12, 2002 11:58 AM
To: Wallace, Steven S; Alan Crosswell; 

Subject: RE: Catalyst RGMP?

At 02:00 PM 11/11/2002 -0500, Wallace, Steven S wrote:
>I would tend to disagree.  If there are only routers connected to the
>6509s, I would think that IGMP snooping should be turned off.

Steve,  You should always turn on IGMP snooping on a 6500..
if you do not, then you are disabling the ASIC switching...
That is the implementation of the 6500.

Tsege

>   Turning
>IGMP snooping on is going to just exercise the code that's looking for
>IGMP host reports (non of which will be coming from the routers).  I
>understood RGMP to be Cisco proprietary solution to the problem you
>describe, although I've never tried it.  Having IGMP and RGMP turned
off
>should work just fine, although you will be flooding some of the
>multicast traffic down links with no downstream listeners (which may be
>just fine if that doesn't cause congestion).
>
>Steven Wallace
>
> > -----Original Message-----
> > From: Tsegreda Beyene 
> > [mailto:]
> > Sent: Friday, November 08, 2002 3:34 PM
> > To: Alan Crosswell; 
> > 
> > Subject: Re: Catalyst RGMP?
> >
> > Hi Alan,
> >
> > comment inline please:
> >
> > At 02:26 PM 11/8/2002 -0500, Alan Crosswell wrote:
> > >Anybody have experience with this?  Is this what I want to use in
>lieu
> > >of the ability to do PIM snooping?
> >
> > No. Cisco does not do PIM snooping.
> >
> > >I have a dual-star L2 topology using
> > Not that this will not work..I prefer point-to-point as opposed to
>dual
> > star.
> >
> > >Catalyst 6509 switches which my routers are each connected to.
Right
> > >now I have IGMP snooping disabled
> >
> > You should always enable IGMP snooping on the 6500..If you disable
it
> > you are basically disabling hardware switching.
> >
> > >on these switches since it seemed to
> > >interfere with multicast connectivity and didn't make sense since
the
> > >only devices on the switch are routers so the only IGMP to snoop
>would be
> > >router advertisements.
> > >
> > >Maybe I should just not touch anything.  It's sort of working
>today:-)
> >
> > I will forward your e-mail to appropriate people and they will help
>you
> > out.
> >
> > Thanks.
> >
> > Best Regards,
> >
> > Tsege
> >
> > >/a