HP ProCurve Series 6120 Blade Switches Multicast and Routing Guide

Multimedia Traffic Control with IP Multicast (IGMP)
How IGMP Operates
IGMP Function Available With IP Addressing
Configured on the VLAN
Available
Without IP
Addressing?
Operating Differences Without an IP Address
Configure IGMP traffic forwarding to normal or Yes None
high-priority forwarding.
Age-Out IGMP group addresses when the last
IGMP client on a port in the VLAN leaves the
group.
Support Fast-Leave IGMP and Forced Fast-
Leave IGMP (below).
Yes
Yes
Requires that another IGMP device in the VLAN has an IP
address and can operate as Querier. This can be a multi-
cast router or another switch configured for IGMP oper-
ation. (ProCurve recommends that the VLAN also include
a device operating as a backup Querier in case the device
operating as the primary Querier fails for any reason.
Support automatic Querier election. No Querier operation not available.
Operate as the Querier. No Querier operation not available.
Available as a backup Querier. No Querier operation not available.
Automatic Fast-Leave IGMP
Fast-Leave IGMP. The switches support Data-Driven IGMP (“Smart” IGMP),
and Fast-Leave is enabled in the default configuration. They drop unjoined
mulitcast traffic except for always-forwarded traffic toward the Querier or
multicast routers, and out of IGMP-forward ports. These switches electively
forward joined multicast traffic.
When unregistered multicasts are received the switch automatically filters
(drops) them. Thus, the sooner the IGMP Leave is processed, the sooner this
multicast traffic stops flowing.
Automatic Fast-Leave Operation. If a switch port has the following char-
acteristics, then the Fast-Leave operation will apply:
1. Connected to only one end node
2. The end node currently belongs to a multicast group; i.e. is an IGMP client
3. The end node subsequently leaves the multicast group
Then the switch does not need to wait for the Querier status update interval,
but instead immediately removes the IGMP client from its IGMP table and
ceases transmitting IGMP traffic to the client. (If the switch detects multiple
end nodes on the port, automatic Fast-Leave does not activate—regardless of
whether one or more of these end nodes are IGMP clients.)
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