Brocade Communications Systems IPMC5000PEF manual Configuring fast leave for MLDv1

Enabling MLDv2 membership tracking and fast leave for the VLAN

Syntax: [no] multicast6 proxy-off

By default, MLD snooping proxy is enabled.

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 multicast6 leave- wait-timecommand. See Enabling or disabling PIM6 SM snooping for more information.

MLDv2 requires that every client respond to queries, allowing the device 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-timebefore 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.

device(config)#vlan 20 device(config-vlan-20)#multicast6 tracking

Syntax: [no] multicast6 tracking

The membership tracking and fast leave features are supported for MLDv2 only. If a port or client is not configured for MLDv2, the multicast6 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. When fast-leave-v1 is configured on a VLAN, make sure you do not have multiple clients on any port that is part of the VLAN. In a scenario where two devices connect, the querier device should not be configured for fast-leave-v1, because the port might have multiple clients through the non-querier. The number of queries and the waiting period (in seconds) can be configured using the ipv6 multicast leave-wait-timecommand. See Enabling or disabling PIM6 SM snooping for more information.

To configure fast leave for MLDv1, use commands such as the following.

device(config)#vlan 20 device(config-vlan-20)#multicast6 fast-leave-v1

Syntax: [no] multicast6 fast-leave-v1

54	FastIron Ethernet Switch IP Multicast Configuration Guide
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