Operation With Or Without Ip Addressing; Automatic Fast-Leave Igmp - HP 2920 Series Multicast And Routing Manual

To display IGMP data showing active group addresses, reports, queries, querier access port, and
active group address data (port, type, and access), see section "Internet Group Management
Protocol (IGMP) Status" in appendix B, "Monitoring and Analyzing Switch Operation" of the
Management and Configuration Guide for your switch.

Operation with or without IP addressing

You can configure IGMP on VLANs that do not have IP addressing. The benefit of IGMP without
IP addressing is a reduction in the number of IP addresses you have to use and configure. This can
be significant in a network with a large number of VLANs. The limitation on IGMP without IP
addressing is that the switch cannot become Querier on any VLANs for which it has no IP
address—so the network administrator must ensure that another IGMP device will act as Querier.
It is also advisable to have an additional IGMP device available as a backup Querier. See
Table 1 Comparison of IGMP operation with and without IP addressing
IGMP function available with IP addressing
configured on the VLAN
Forward multicast group traffic to any port on
the VLAN that has received a join request for
that multicast group.
Forward join requests (reports) to the Querier.
Configure individual ports in the VLAN to Auto
(the default)/Blocked, or Forward.
Configure IGMP traffic forwarding to normal
or 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.)
Support automatic Querier election.
Operate as the Querier.
Available as a backup Querier.

Automatic fast-leave IGMP

Depending on the switch model, fast-leave is enabled or disabled in the default configuration.
Switch model or series
Switch 8200zl
Switch 6600
Switch 6400cl
Available without IP
Data-driven IGMP IGMP fast-leave
included? setting
Yes Always Enabled
Operating differences without an IP address
addressing?
Yes
Yes
Yes
Yes
Yes Requires that another IGMP device in the VLAN
has an IP address and can operate as Querier.
This can be a multicast router or another switch
configured for IGMP operation. (HP
Yes
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.)
No Querier operation not available.
No Querier operation not available.
No Querier operation not available.
Default IGMP behavior
Drops unjoined mulitcast traffic except for
always-fowarded traffic toward the Querier or
multicast routers and out of IGMP-forward
ports. Selectively forwards joined multicast
Table 1.
None
None
None
None
How IGMP operates 15