July 2021
43
PWVIA RM P12 Ethernet Switches - Manual
NOTES ON IGMP
The IGMP Querier establishes a table of active multicast groups by querying connected devices about which multicast
groups each device wishes to join. For example, a gateway will request the multicast groups associated with the sACN
universes that the gateway is patched to.
Each switch operating an IGMP Querier on a VLAN must have valid IP settings on that VLAN. The IP settings may be static
or dynamically established using the DHCP.
IMPORTANT:
Two IGMP queriers should be active on each VLAN using multicast filtering. If no querier is active, the
groupings table will fail after approximately five minutes and filtering will only work erratically or will fail altogether. IGMP
should not be enabled on more than four VLANs per switch.
The IGMP Snooper allows the switch to more efficiently route multicast traffic by applying the multicast groupings as a filter.
Multicast traffic is only directed to only those ports, i.e. end devices, that have requested to receive that traffic.
Watch the following video on Pathway’s YouTube channel for a detailed explanation of IGMP Snooping:
https://www.youtube.com/watch?v=0MVE22JCIt4
And the following video for a real-world example.
Summary of Contents for VIA PWVIA RM P12
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