| Tag Name | mcast_groups |
| Usage | mcast_groups IPAddress |
Description
This tag specifies a list of multicast groups, with which your server should join to receive multicasted ICP queries.
Multicast is essentially the ability to send one IP packet to multiple receivers. Multicast is often used for audio and video conferencing systems. If you are unsure about multicast, please read the Multicast chapter in the Squid FAQ (http://squid.nlanr.net/Squid/FAQ/).
This option is to be set only if you want to RECEIVE multicast queries.
ICP replies are always sent via unicast, so this option does not affect whether or not you will receive replies from multicast group members.
Be sure you understand the difference between an ICP _query_ and an ICP _reply_.
Use cache_peer Directive for sending ICP queries.
| Default | none By default, Squid doesn’t listen on any multicast groups |
Example
mcast_groups 239.128.16.128 224.0.1.20
Caution
Should not use a multicast address, which is already in use by another group of caches. We should not set this option to SEND multicast ICP.
