Operating Features; Operation With Or Without Ip Addressing - HP procurve 8100fl series Management And Configuration Manual

Multimedia Traffic Control with IP Multicast (IGMP)
How IGMP Operates
10-10
When a networking device with IGMP enabled receives the join request
■
for a specific group, it forwards any IP multicast traffic it receives for that
group through the port on which the join request was received.
■ When the client is ready to leave the multicast group, it sends a Leave
Group message to the network and ceases to be a group member.
When the leave request is detected, the appropriate IGMP device will
■
cease transmitting traffic for the designated multicast group through the
port on which the leave request was received (as long as there are no other
current members of that group on the affected port).

Operating Features

The following IGMP operations and features are supported on the 8100fl
switch:
Operation With or Without IP Addressing: This feature helps to
■
conserve IP addresses by enabling IGMP to run on VLANs that do not have
an IP address. See "Operation With or Without IP Addressing" on page
10-10.
■ Querier Capability: The switch performs this function for IGMP on
VLANs having an IP address when there is no other device in the VLAN
acting as querier. See "Using the Switch as Querier" on page 10-14.
Automatic Fast-Leave IGMP: Fast-Leave is enabled in the default
■
configuration. This feature drops unjoined mulitcast traffic except for
always-fowarded traffic toward the Querier or multicast routers, and out
of IGMP-forward ports. See "Automatic Fast-Leave IGMP" on page 10-11.
■ Forced Fast-Leave IGMP: This feature speeds up the process of block­
ing unnecessary IGMP traffic to a switch port that is connected to multiple
end nodes. See "Forced Fast-Leave IGMP" on page 10-13.

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.