User`s manual
IKS-6726 Featured Functions
3-47
Network with multicast filtering
IGMP Group2
Group 1 Multicast Stream Group 2 Multicast Stream
IGMP Group1 IGMP Group2 IGMP Group1
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24
57
68
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5
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TX RX
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M2
M1
IKS-6726
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TX RX
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TX RX
STAT
FAULT
PWR1
MASTER
PWR2
COUPLER
LNK/ACT SPEED FDX/HDX
RING PORT
COMUPLER
PORT
MODE
1
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68
M1
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Hosts only receive dedicated traffic from other hosts belonging to the same group.
Multicast Filtering and Moxa’s Industrial Rackmount switches
The IKS-6726 has three ways to achieve multicast filtering: IGMP (Internet Group Management Protocol)
Snooping, GMRP (GARP Multicast Registration Protocol), and adding a static multicast MAC manually to filter
multicast traffic automatically.
IGMP (Internet Group Management Protocol)
Snooping Mode
Snooping Mode allows your switch to forward multicast packets only to the appropriate ports. The switch
snoops on exchanges between hosts and an IGMP device, such as a router, to find those ports that want to join
a multicast group, and then configures its filters accordingly.
IGMP Snooping Enhanced Mode
Snooping Enhanced Mode allows your switch to forward multicast packets to the IKS-6726’s member port only.
If you disable Enhanced Mode, data streams will run to the querier port as well as the member port.
Query Mode
Query mode allows the IKS-6726 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 IKS-6726 to help prevent interoperability issues
with some multicast routers that may not follow the lowest IP address election method. Enable query mode to
run multicast sessions on a network that does not contain IGMP routers (or queriers).
NOTE IKS-6726 is compatible with any device that conforms to the IGMP v2 and IGMP v3 device protocol.
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. IGMP works as follows:
The IP router (or querier) periodically sends query packets to all end-stations on the LANs or VLANs that are
connected to it. For networks with more than one IP router, the router with the lowest IP address is the querier.
A switch with IP address lower than the IP address of any other IGMP queriers connected to the LAN or VLAN
can become the IGMP querier.
When an IP host receives a query packet, it sends a report packet back that identifies the multicast group that
the end-station would like to join.