Multimedia Traffic Control with IP Multicast (IGMP)
How IGMP Operates
4-2.Switches Supported for IGMP Features
Switch Model Data- IGMP Fast- Default IGMP Behavior
or Series Driven Leave Setting
IGMP
Included?
Switch 8212zl
Yes Always Drops unjoined mulitcast traffic except for
Switch 6400cl
Enabled always-fowarded traffic toward the Querier or
Switch 6200yl
Switch 5400zl
multicast routers, and out of IGMP-forward
ports. Selectively forwards joined multicast
traffic.
Switch 5300xl
Switch 4200vl
Switch 3500yl
Switch 3400cl
Switch 2610
Switch 2610-
PWR
Switch 2500
Switch 2600
No Disabled in IGMP Fast-Leave disabled in the default
Switch 2600-
the Default configuration. Floods unjoined multicast traffic
PWR
Configuration to all ports. Selectively forwards joined
Switch 4100gl
multicast traffic.
Switch 6108
On switches that do not support Data-Driven IGMP, unregistered multicast
groups are flooded to the VLAN rather than pruned. In this scenario, Fast-
Leave IGMP can actually increase the problem of multicast flooding by
removing the IGMP group filter before the Querier has recognized the IGMP
Leave. The Querier will continue to transmit the multicast group during this
short time, and because the group is no longer registered the switch will then
flood the multicast group to all ports.
The switches covered in this guide support Data-Driven IGMP (“Smart”
IGMP), which is enabled by default. Data-Driven IGMP prunes off any
unregistered IGMP streams detected on the switch. Thus, the sooner the IGMP
Leave is processed, the sooner this multicast traffic stops flowing.
Because of the multicast flooding problem mentioned above, the IGMP
FastLeave feature is disabled by default on all ProCurve switches that do not
support Data-Driven IGMP. (See table 4-2, above.) The feature can be enabled
on these switches via an SNMP set of this object:
hpSwitchIgmpPortForceLeaveState.< vid >.< port number >
However, this is not recommended as this will increase the amount of
multicast flooding during the period between the client's IGMP Leave and the
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