Hirschmann GREYHOUND GRS1020, Reference Manual

Page: 155 / 619

Switching
[ Switching > IGMP Snooping ]
154
RM GUI GRS
Release 8.0 09/2019
5.4 IGMP Snooping
[ Switching > IGMP Snooping ]
The Internet Group Management Protocol (IGMP) is a protocol for dynamically managing Multicast
groups. The protocol describes the distribution of Multicast data packets between routers and end
devices on Layer 3.
The device lets you use the IGMP Snooping function to also use the IGMP mechanisms on Layer 2:

Without IGMP Snooping, the device transmits the Multicast data packets to every port.

With the activated IGMP Snooping function, the device transmits the Multicast data packets only
on ports to which Multicast receivers are connected. This reduces the network load. The device
evaluates the IGMP data packets transmitted on Layer 3 and uses the information on Layer 2.

Activate the IGMP Snooping function not until the following conditions are fulfilled:
– There is a Multicast router in the network that creates IGMP queries (periodic queries).
– The devices participating in IGMP Snooping forward the IGMP queries.
The device links the IGMP reports with the entries in its address table. When a multicast receiver
joins a multicast group, the device creates a table entry for this port in the
Switching > Filter for MAC
Addresses
dialog. When the multicast receiver leaves the multicast group, the device removes the
table entry.
The menu contains the following dialogs:

IGMP Snooping Global

IGMP Snooping Configuration

IGMP Snooping Enhancements

IGMP Snooping Querier

IGMP Snooping Multicasts