Operation With Or Without Ip Addressing; Automatic Fast-Leave Igmp - HP ProCurve Series 4100GL Management And Configuration Manual

Table 13-1.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 (below) and Forced
Fast-Leave IGMP (page 13-13).
Support automatic Querier election.
Operate as the Querier.
Available as a backup Querier.

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 the following table.
Available
Without IP
Addressing?
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No

Automatic Fast-Leave IGMP

IGMP Operation Presents a "Delayed Leave" Problem. Where multiple
IGMP clients are connected to the same port on an IGMP device (switch or
router), if only one IGMP client joins a given multicast group, then later sends
a Leave Group message and ceases to belong to that group, the IGMP device
retains that IGMP client in its IGMP table and continues forwarding IGMP
traffic to the IGMP client until the Querier triggers confirmation that no other
Multimedia Traffic Control with IP Multicast (IGMP)
Operating Differences
Without an IP Address
None
None
None
None
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. (HP 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.
Querier operation not available.
Querier operation not available.
Querier operation not available.
How IGMP Operates
13-13