All things related to multicast

[Alan Crosswell <>]

> We've got several hundred mbps of multicast running 7x24 on our catalyst.  
> I believe you simply need to engage snooping, plus the catalyst has a very 
> bad artifact: there must be at least one receiver to each multicast or it 
> floods.  We get around this by having our sources join their own multicast.
> 
> hope this helps
> 
> Rich
> 
> 
> -----Original Message-----
> From: Alan Crosswell 
> [mailto:]
> Sent: Thursday, May 02, 2002 12:53 PM
> To: 
> 
> Subject: link-layer IP multicast vs. L2 switches
> 
> 
> Does anybody know if there's a way to get link-layer IP multicast to do
> the "right thing"?  I discovered that my link-layer multicasts were being
> flooded by my Catalyst 4000 switch.  I think maybe this is just the way it
> is since I would guess that by definition link-layer multicast doesn't ever
> speak to the IGMP router.
> 
> I guess I will implement my subnet multicast with admin-scoped groups and
> filters on my routers instead....
> 
> Comments, corrections, commissertaion? :-)
> 
> /a
> 

Are you doing link-layer multicast?  When I switched to admin-scoped,
even with no viewers on the local subnet there was no flooding.
/a