mld-snooping

List of Syntax

Syntax (ACX Series, EX9200, and MX Series)

Syntax (EX Series and SRX Series)

Syntax (QFX Series)

Hierarchy Level

Release Information

Statement introduced in Junos OS Release 12.1.

Description

Enable and configure Multicast Listener Discovery (MLD) snooping. MLD snooping constrains IPv6 multicast traffic at Layer 2 by configuring Layer 2 LAN ports dynamically to forward IPv6 multicast traffic only to those ports that want to receive it.

MLD is a protocol built on ICMPv6 and used by IPv6 routers and hosts to discover and indicate interest in a multicast group, similar to how IGMP manages multicast group membership for IPv4 multicast traffic. There are two versions, MLDv1 (RFC 2710), which is equivalent to IGMP version 2 (IGMPv2), and MLDv2 (RFC 3810), which is equivalent to IGMP version 3 (IGMPv3). Like IGMP, both MLDv1 and MLDv2 support Query, Report and Done messages. MLDv2 further supports source-specific Query messages (reports) and multi-record reports. MLD configuration options are similar to those for IGMP snooping.

MLD restricts forwarding IPv6 multicast traffic to only those interfaces in a bridge-domain, VLAN, or VPLS that have interested listeners, rather than flooding the traffic to all interfaces in the bridge-domain, VLAN, or VPLS. The device finds the interfaces with interested listeners using the following steps:

• Snoops or monitors MLD control packets.

• Identifies the set of outgoing interfaces for a multicast stream.

• Builds the forwarding state accordingly.

The device snoops Query messages and floods them to all ports. The device snoops Report and Done messages and selectively forwards them only to multicast router ports.

The remaining statements are explained separately. See CLI Explorer.

Default

MLD snooping is disabled.

Required Privilege Level

routing—To view this statement in the configuration.

routing-control—To add this statement to the configuration.