hello We have a multicast address (234.234.234.234) that is configured on each of our 10 proxy servers so that ICP sibling proxies can efficiently broadcast ICP requests to each other. Some percentage of ICP requests (10 to 20%) time out without ever getting a reply from siblings. This results in delays and retries for all proxies. Unfortunately the ICP protocol does not provide much useful diagnostic information, so the multicast problem can best be seen by examining ping replies. It appears that about 20% of multicast requests are mis-routed (seem to be routed through the wrong adapter) and lost. When we ping 234.234.234.234, we should get normally 9 ICMP replies from the remaining proxies. But if the same ping is allowed to run for a longer time, then it becomes clear that some multicast traffic is apparently sent across the wrong network adapters (because replies come from unexpected addresses). Also the amplification factor drops from 9 to 7.11 which implies that ICP sibling proxies didn't receive the multicast requests and thus didn't reply to them. For instance, we see some ping failures from subnets other than the ICP subnet. We also miss the 9 multicast replies from the sibling. Can you please shed some lights on this issue? thanks, Mel ___________________________________________________________ To help you stay safe and secure online, we've developed the all new Yahoo! Security Centre. http://uk.security.yahoo.com
