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Alteon OS Application Guide
168
Chapter 10: IGMP 42C4911, January 2007
Additional IGMP Features
The following topics are discussed in this section:
“FastLeave” on page 168
“IGMP Filtering” on page 168
FastLeave
In normal IGMP operation, when the receives an IGMPv2 leave message, it sends a Group-
Specific Query to determine if any other devices in the same group (and on the same port) are
still interested in the specified multicast group traffic. The switch removes the affiliated port
from that particular group, if the following conditions apply:
If the switch does not receive an IGMP Membership Report within the query-response-
interval.
If no multicast routers have been learned on that port.
With FastLeave enabled on the VLAN, a port can be removed immediately from the port list of
the group entry when the IGMP Leave message is received, unless a multicast router was
learned on the port.
Enable FastLeave only on VLANs that have only one host connected to each physical port.
IGMP Filtering
With IGMP Filtering, you can allow or deny a port to send and receive multicast traffic to cer-
tain multicast groups. Unauthorized users are restricted from streaming multicast traffic across
the network.
If access to a multicast group is denied, IGMP Membership Reports from the port are dropped,
and the port is not allowed to receive IP multicast traffic from that group. If access to the mul-
ticast group is allowed, Membership Reports from the port are forwarded for normal process-
ing.
To configure IGMP Filtering, you must globally enable IGMP filtering, define an IGMP filter,
assign the filter to a port, and enable IGMP Filtering on the port. To define an IGMP filter, you
must configure a range of IP multicast groups, choose whether the filter will allow or deny
multicast traffic for groups within the range, and enable the filter.
Configuring the Range