[c-nsp] IP multicast traffic overwhelms switches

[victor]

Hi
We are getting ready a residential triple-play network for the launch. As  
part of my job I'm conducting various tests on its performance, delays,  
etc before we go into production. Today was the multicast time and testing  
it I got very discouraging results. Under very moderate load of 15 IPTV  
streams (each approximately 1-1,5Mbps) the cpu gauge on the core C7604  
increased by 15% but on the distribution C4924 hit 50% from zero!  When I  
went on with the test and launched iperf adding one more 50 Mbps stream in  
udp multicact mode to stress-test both even more the cpu utilization on   
C7604 became 60% and on C4924 hit 100%. It even became visible as the  
responses of the telnet console considerable slowed down.
Both switches work as ip multicast routers in sparse-dense mode. The RP is  
C7604. Apparently all the multicast traffic gets process switched, though  
I explicitly entered “ip mroute-cache” under every interface.
Did someone encounter something similar? Is it expected behavior? Is there  
a way to force cef to do it's job. Specs say that  C4924 can switch/route  
up to 72gbps irrespectively of L2/L3/L4 protocol.

wbr victor



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