How do I configure Squid to send Multicast ICP queries?
To configure Squid to send ICP queries to a Multicast address, you need to create another neighbour cache entry specified as multicast. For example: cache_peer 224.9.9.9 multicast 3128 3130 ttl=64 224.9.9.9 is a sample multicast group address. multicast indicates that this is a special type of neighbour. The HTTP-port argument (3128) is ignored for multicast peers, but the ICP-port (3130) is very important. The final argument, ttl=64 specifies the multicast TTL value for queries sent to this address. It is probably a good idea to increment the minimum TTL by a few to provide a margin for error and changing conditions. You must also specify which of your neighbours will respond to your multicast queries, since it would be a bad idea to implicitly trust any ICP reply from an unknown address. Note that ICP replies are sent back to unicast addresses; they are NOT multicast, so Squid has no indication whether a reply is from a regular query or a multicast query. To configure your multicast
