Allied Telesis AR400 - Manual (Page 14)

Page 14 | AlliedWare™ OS How To Note: IGMP
IGMP snooping > Explanation of IGMP snooping
Finally, look at the output of the command show igmpsnooping on the Querier. Even
though switch 1 is the Querier for this network instead of a Snooper, this command shows
that a client for group 224.12.13.14 is reached out port 49.
When a client leaves a group
When a client wants to stop receiving a group’s multicast stream, it sends an IGMP Leave
message with a destination address of the group. The Snooper forwards the Leave message
out its All Groups port, so the message arrives at the IGMP Querier. At this point, the IGMP
Querier sends a series of Specific Queries (2 by default) to see if anybody else is still listening
to this group.
If the Snooper receives a response to the Specific Queries, it forwards the response to the
Querier and continues to forward the multicast stream to the ports that want to receive it. If
the Snooper does not receive a response to the Specific Queries, it stops forwarding the
stream.
For a detailed description of how the leave process works, see "How clients leave groups:
queries and timers" on page 58 .
Manager Switch 1> show igmpsnooping
IGMP Snooping
------------------------------------------------------------------------
Status ........................... Enabled
Disabled All-groups ports ........ None
Vlan Name (vlan id) ..... default (1)
Fast Leave .............. Off
Group List ..............
No group memberships.
Vlan Name (vlan id) ..... vlan100 (100)
Fast Leave .............. Off
Group List ..............
Group. 224.12.13.14 Entry timeout 247 secs
Ports 49
------------------------------------------------------------------------