By default, unregistered multicast data packets are flooded to all ports in the VLAN.
By creating static Layer 2 multicast forwarding entries, multicast groups can be registered, and data can
be forwarded only to selected ports.
Version Compatibility
The following table outlines the
/MLD versions the 200 Series snooping switch supports.
Table 323: IGMP/MLD Version Support
Protocol Version
Support
IGMPv1
Yes
IGMPv2
Yes
IGMPv3
No
MLDv1
Yes
MLDv2
No
Snooping Switch Restrictions
This section describes the
and MLD Snooping implementation on a 200 Series-based snooping
switch.
MAC Address-Based Multicast Group
The L2 multicast forwarding table (built using IGMPV2/V1 reports) consists of the IP Multicast group
MAC address. For IPv4 multicast groups, 16 IP multicast group addresses map to the same multicast
MAC address. For example, 224.1.1.1 and 225.1.1.1 map to the MAC address 01:00:5E:01:01:01, and IP
addresses in the range [224-239].3.3.3 map to 01:00:5E:03:03:03. As a result, if a host requests 225.1.1.1
using IGMPv2 or IGMPv1, then it might receive multicast traffic of group 226.1.1.1 as well.
IGMP Snooping in a Multicast Router
snooping is a Layer 2 feature and is achieved by using the Layer 2 multicast forwarding table.
However when multicast routing is enabled on a 200 Series switch, Layer 2 multicast forwarding entries
do not affect multicast data forwarding. Instead, corresponding IP multicast table entries need to be
created to achieve similar behavior.
On a multicast router, for IGMP snooping to be functional, any multicast routing protocol needs to be
operationally enabled on the routing interface. IGMP snooping also needs to be enabled on the VLAN
corresponding to the routing interface. Note that IGMP snooping behavior will not be functional on
VLANs that are not enabled for VLAN routing.
Configuring IGMP and MLD Snooping
The command-line interface (CLI) includes several commands that are used to configure the
MLD snooping features. For more information about each command, and for information about
Configuration Examples
ExtremeSwitching 200 Series: Administration Guide
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