Configuration Guide User guide

FastIron Configuration Guide 1641
53-1002494-02
MLD snooping configuration
Enabling MLDv2 membership tracking and fast leave
for the VLAN
MLDv2 provides membership tracking and fast leave services to clients. In MLDv1, only one client
per interface must respond to a router queries; leaving some clients invisible to the router, which
makes it impossible for the device to track the membership of all clients in a group. In addition,
when a client leaves the group, the device 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 device waits a few seconds before stopping the traffic. You can configure the wait
time with the ipv6 mld-snooping leave-wait-time command.
MLDv2 requires that every client respond to queries, allowing the device is able to track every
client. When the tracking feature is enabled, the device immediately stops forwarding traffic to the
interface if an MLDv2 client sends a leave message, and there is no other client. This feature
requires the entire VLAN to be configured for MLDv2 and have no MLDv1 clients. If a client does
not send a report during the specified group membership time (the default is 140 seconds), that
client is removed from the tracking list.
Every group on a physical port keeps its own tracking record. However, it can track group
membership only; it cannot track by (source, group). For example, Client A and Client B belong to
group1 but each is receiving traffic from different sources. Client A receives a traffic stream from
(source_1, group1) and Client B receives a traffic stream from (source_2, group1). The device waits
for the configured leave-wait-time before it stops the traffic because the two clients are in the same
group. If the clients are in different groups, the waiting period is ignored and traffic is stopped
immediately.
To enable tracking and fast leave for VLAN 20, enter the following commands.
Brocade(config)#vlan 20
Brocade(config-vlan-20)#mld-snooping tracking
Syntax: [no] mld-snooping tracking
The membership tracking and fast leave features are supported for MLDv2 only. If a port or client is
not configured for MLDv2, the mld-snooping tracking command is ignored.
Configuring fast leave for MLDv1
When a device receives an MLDv1 leave message, it sends out multiple group-specific queries. If
no other client replies within the waiting period, the device stops forwarding traffic to this port.
Configuring fast-leave-v1 allows the device to stop forwarding traffic to a port immediately upon
receiving a leave message. The device does not send group-specific queries. It is important that no
snooping ports have multiple clients. When two devices connect, the querier device should not be
configured for fast-leave-v1 because the port to the non-querier device could have multiple clients.
The number of queries and the waiting period (in seconds) can be configured using the ipv6
mld-snooping leave-wait-time command. The default is 2 seconds. To configure fast leave for
MLDv1, use commands such as the following.
Brocade(config)#vlan 20
Brocade(config-vlan-20)#mld-snooping fast-leave-v1
Syntax: [no] mld-snooping fast-leave-v1