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PT-G7828/G7728
Featured Functions
3-53
IGMP version 3 supports “source filtering,” which allows the system to define how to treat packets from
specified source addresses. The system can either white-list or black-list specified sources.
IGMP version comparison
IGMP Version
Main Features
Reference
V1
Periodic query
RFC-1112
V2
Compatible with V1 and adds:
a. Group-specific query
b. Leave group messages
c. Resends specific queries to verify leave message was the last one in
the group
d. Querier election
RFC-2236
V3
Compatible with V1, V2, and adds:
Source filtering
- accept multicast traffic from specified source
- accept multicast traffic from any source except the specified source
RFC-3376
GMRP (GARP Multicast Registration Protocol)
Moxa switches support IEEE 802.1D-1998 GMRP (GARP Multicast Registration Protocol), which is different 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
will not be 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 Moxa
switch supports adding multicast groups manually to enable multicast filtering.
Enabling Multicast Filtering
Use the USB 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.
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.
NOTE
IGMP Snooping will be disabled when Port-Based VLAN is enabed.
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