Wavetronix Click 342 (lean managed ethernet switch) (CLK-342) - Managed Switches User Guide - Manual (Page 70)

CHAPTER 7 • MULTICAST FILTERING 69
General Multicast Configuration Website
The General Multicast Configuration website provides global settings for multicast support.
Here, IGMP snooping can be enabled and an aging time can be specified for IGMP snoop-
ing information (see Figure 7.1).
Figure 7.1 – General Multicast Configuration Website
Note
The switch supports 50 multicast groups at the same time.
˽ IGMP snooping – In IGMP snooping, the switch passively listens in on the IGMP mes-
sages that are sent over the network and dynamically creates the appropriate groups.
These groups are not stored and will be lost with every power-down or when switching
off the snooping function.
˽ IGMP Query – A managed switch with activated query function actively transmits que-
ries at intervals and evaluates the received reports. The switch only sends IGMP query
reports if IGMP snooping is enabled.
GMRP (GARP Multicast Registration Protocol) is a GARP (Generic Attribute Registration
Protocol) application that allows the distribution of multicast group destination addresses
to layer two devices that don’t support IGMP snooping. After a multicast participant has
registered with the switch (e.g. through an IGMP report), the switch sends a GMRP broad-
cast packet to all GARP participating switches with the Multicast Group Destination Ad-
dress and whether the switch is joining or leaving. This allows the other switches to create
their own multicast groups and add the receiving port to the group. By default GMRP is
enabled when IGMP snooping is enabled. The receiving switches do not need to support
IGMP snooping to receive and understand the GMRP packets they receive.