[c-nsp] multicast bringing big irons to their knees?

[Christian MacNevin]

Hi
I've only got the most superficial of ideas what's going on with this  
network, but i've been asked if there's any particular reason
some Foundry switches would be being brought to their knees every time  
mcast is switched on in a network. 65s, 3750s and Netscreens
all handle it fine.
Given Foundry's marketing, they dobrag that everything's handled in  
port-based ASICs, but obviously it sounds like this stuff is going
to the processor. Maybe it's PIM Sniffing not supported in hardware,  
not sure.
Anyway, sorry for the amazing vagary here, but it's all I've got right  
now. Any thoughts?
Cheers
Christian