HP procurve 2500 Manuale Utente
210
Enhancements in Release F.02.02
Operation and Enhancements for Multimedia Traffic Control (IGMP)
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.
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,
client leaves a multicast group, Fast-Leave IGMP automatically accelerates the blocking of further,
IGMP Function Available With IP Addressing
Configured on the VLAN
Configured on the VLAN
Available
Without IP
Addressing?
Without IP
Addressing?
Operating Differences Without an IP Address
Drop multicast group traffic for which there
have been no join requests from IGMP clients
connected to ports on the VLAN.
have been no join requests from IGMP clients
connected to ports on the VLAN.
Yes
None
Forward multicast group traffic to any port on
the VLAN that has received a join request for
that multicast group.
the VLAN that has received a join request for
that multicast group.
Yes
None
Forward join requests (reports) to the Querier.
Yes
None
Configure individual ports in the VLAN to Auto
(the default)/Blocked, or Forward.
(the default)/Blocked, or Forward.
Yes
None
Configure IGMP traffic forwarding to normal or
high-priority forwarding.
high-priority forwarding.
Yes
None
Age-Out IGMP group addresses when the last
IGMP client on a port in the VLAN leaves the
group.
IGMP client on a port in the VLAN leaves the
group.
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.
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 Fast-Leave IGMP (below) and Forced
Fast-Leave IGMP (page 212).
Fast-Leave IGMP (page 212).
Yes
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.