Brocade TurboIron 24X Series Configuration Guide - Manual (Page 891)

Brocade TurboIron 24X Series Configuration Guide 857
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IGMP V3
Enabling membership tracking and fast leave
IGMP V3 provides membership tracking and fast leave to clients. In IGMP V2, only one client on an
interface needs to respond to a router queries; therefore, some of the clients may be invisible to
the router, making it impossible for the router to track the membership of all clients in a group.
Also, when a client leaves the group, the router sends group specific queries to the interface to see
if other clients on that interface need the data stream of the client who is leaving. If no client
responds, the router waits three seconds before it stops the traffic.
IGMP V3 contains the tracking and fast leave feature that you enable on virtual routing interfaces.
Once enabled, all physical ports on that virtual routing interface will have the feature enabled.
IGMP V3 requires all clients to respond to general and group specific queries so that all clients on
an interface can be tracked. Fast leave allows clients to leave the group without the three second
waiting period, if the following conditions are met:
• If the interface, to which the client belongs, has IGMP V3 clients only. Therefore, all physical
ports on a virtual routing interface must have IGMP V3 enabled and no IGMP V1 or V2 clients
can be on the interface. (Although IGMP V3 can handle V1 and V2 clients, these two clients
cannot be on the interface in order for fast leave to take effect.)
• No other client on the interface is receiving traffic from the group to which the client belongs.
Every group on the physical interface of a virtual routing interface keeps its own tracking
record. However, it can track group membership only; it cannot track by (source, group).
For example, two clients (Client A and Client B) belong to group1 but each is receiving traffic
streams from different sources. Client A receives a stream from (source_1, group1) and Client B
receives it from (source_2, group1). The router still waits for three seconds before it stops the
traffic because the two clients are in the same group. If the clients are in different groups, then the
three second waiting period is not applied and traffic is stopped immediately. The show ip igmp
group tracking command displays that clients in a group that are being tracked.
If a client sends a leave message, the client is immediately removed from the group. If a client does
not send a report during the the specified group membership time (the default is 140 seconds),
that client is removed from the tracking list.
Using the CLI
To enable the tracking and fast leave feature, enter commands such as the following.
TurboIron(config)#interface ve 13
TurboIron(config-vif-13)#ip igmp tracking
Syntax: ip igmp tracking
Setting the query interval
The IGMP query interval period defines how often a router will query an interface for group
membership. Possible values are 10 – 3,600 seconds and the default value is 60 seconds, but
the value you enter must be a little more than twice the group membership time.
To modify the default value for the IGMP query interval, enter the following.
TurboIron(config)#ip igmp query-interval 120
Syntax: ip igmp query-interval <10-3600>
The interval must be a little more than two times the group membership time.