User Documentation

User Manual Managed Switches

IGMP Version

Main Features

Reference

Periodic query

RFC-1112

Compatible with V1 and adds:

• Group-specific query

• Leave group messages

• Resends specific queries to verify leave message was the

last one in the group

• Querier election

RFC-2236

GMRP (GARP Multicast Registration Protocol)

Weidmüller managed switches support IEEE 802.1D-1998 GMRP (GARP Multicast Registration

Protocol), which differs from IGMP (Internet Group Management Protocol). GMRP is a MAC-based

multicast management protocol, whereas IGMP is IP-based. GMRP provides a mechanism that

allows bridges and end stations to register or de-register Group membership information dynamically.

GMRP functions similarly to GVRP, except that GMRP registers multicast addresses on ports. When

a port receives a GMRP-join message, it will register the multicast address to its database if the

multicast address is not registered, and all the multicast packets with that multicast address are able

to be forwarded from this port. When a port receives a GMRP-leave message, it will de-register the

multicast address from its database, and all the multicast packets with this multicast address are not

able to be forwarded from this port.

Static Multicast MAC

Some devices may only support multicast packets, but not support either IGMP Snooping or GMRP.

The Weidmüller switch supports adding multicast groups manually to enable multicast filtering.

Enabling Multicast Filtering

Use the serial console or web interface to enable or disable IGMP Snooping and IGMP querying. If

IGMP Snooping is not enabled, then IP multicast traffic is always forwarded, flooding the network.

3.8.2 Configuring IGMP Snooping

IGMP Snooping provides the ability to prune multicast traffic so that it travels only to those end

destinations that require that traffic, thereby reducing the amount of traffic on the Ethernet LAN.