ToughNet NAT Router User's Manual
TN-5916 Series Features and Functions
3-19
Network without multicast filtering
All hosts receive the multicast
traffic, even if they don’t need it.
Network with multicast filtering
Hosts only receive dedicated
traffic from other hosts
belonging to the same group.
Multicast Filtering and Moxa’s ToughNet NAT Routers
The Moxa ToughNet NAT Router has two ways to achieve multicast filtering: IGMP (Internet Group
Management Protocol) Snooping and adding a static multicast MAC manually to filter multicast traffic
automatically.
Snooping Mode
Snooping Mode allows your ToughNet NAT Router to forward multicast packets only to the appropriate ports.
The router
snoops
on exchanges between hosts and an IGMP device to find those ports that want to join a
multicast group, and then configures its filters accordingly.
Query Mode
Query mode allows the Moxa router to work as the Querier if it has the lowest IP address on the subnetwork to
which it belongs.
IGMP querying is enabled by default on the Moxa router to ensure proceeding query election. Enable query
mode to run multicast sessions on a network that does not contain IGMP routers (or queriers). Query mode
allows users to enable IGMP snooping by VLAN ID. Moxa ToughNet NAT Router support IGMP snooping version
1 and version 2. Version 2 is compatible with version 1.The default setting is IGMP V1/V2. "
IGMP Multicast Filtering
IGMP is used by IP-supporting network devices to register hosts with multicast groups. It can be used on all
LANs and VLANs that contain a multicast capable IP router, and on other network devices that support
multicast filtering. Moxa switches support IGMP version 1 and 2. IGMP version 1 and 2 work as follows::
