27
IGMP Snooping Configuration
Wh n configuring IGMP snooping
e
IGMP Snooping Overview
Configuring IGMP Snooping
Displaying and Maintaining IGMP Snooping
IGMP Snooping Configuration Examples
Troubleshooting IGMP Snooping
In this manual, the term "router" refers to a router in the generic sense or a Layer 3 Ethernet switch
ru
nning an IP multicast protocol.
IGM
P Snooping Overview
Internet Group Management Protocol Snooping (IGMP Snooping) is a multicast constraining
mechanism that runs on Layer
Princ
iple of IGMP Snooping
By analyzin
g received IGMP messages, a Layer 2 device running IGMP Snooping establishes
mappings between ports and multicast MAC addresses and forwards multicast data based on these
mappings.
As shown in
Figure
broadcast to all devices at Layer 2. When IGMP Snooping is running on the switch, multicast packets for
known multicast groups are multicast to the receivers, rather than broadcast to all hosts, at Layer 2.
However, multicast packets for unknown multicast groups are still broadcast at Layer 2.
, go to these sections for information you are interested in:
2 devices to manage and control multicast groups.
27-1, when IGMP Snooping is not running on the switch, multicast packets are
27-1