Filter
Top Products
Multimedia Traffic Control with IP Multicast (IGMP)
More on IGMP Operation
IGMP Function Available With IP Addressing
Configured on the VLAN
Available
Without IP
Addressing?
Operating Differences Without an IP Address
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 18).
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. (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.
Support automatic Querier election. No Querier operation not available.
Operate as the Querier. No Querier operation not available.
Provide a backup Querier. No Querier operation not available.
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
group members exist on the same port. This means that the switch continues
to transmit unnecessary multicast traffic through the port until the Querier
renews multicast group status.
Fast-Leave IGMP Reduces Leave Delays. Fast-Leave IGMP operates on a
port if an IGMP client connects to the port and there are no other end nodes
detected on that port. In this case, when the client leaves a multicast group,
Fast-Leave IGMP automatically accelerates the blocking of further, unneces-
sary multicast traffic from that group to the former IGMP client. This improves
performance by reducing the amount of multicast traffic going through the
port to the IGMP client after the client leaves a multicast group. IGMP in the
Series 5300XL switches automatically uses this Fast-Leave feature.
Automatic Fast-Leave Operation. If a Series 5300XL switch port is:
a. Connected to only one end node
b. The end node currently belongs to a multicast group; i.e. is an IGMP
client
c. The end node subsequently leaves the multicast group
12-16