Siemens SLI-5310 User Manual page 83

Now suppose the video server is the multicast transmitter and host A and D are
multicast receivers. If we do not turn on the IGMP snooping function, the router will
forward the multicast traffic to all hosts connecting to this router and consequently
block and interrupt the traffic of the other users who do not want to receive the
multicast service, shown as the following figure.
When IGMP snooping is invoked, it makes the system aware to establish the best
path for multicast service to save LAN bandwidth. Refer the figure below, just as
desired, only host A and D will actually receive multicast traffic when IGMP snooping
is enabled.
While IGMP snooping is enabled, the
IGMP packets will be monitored, the
membership information will be
recorded and processed, and the
multicast traffic will only be forwarded
to those LAN interfaces, such as
Ethernet and USB, which are bonded
to the subscribed multicast groups.
Thus it helps to save the bandwidth
and helps the devices to perform
more effectively.
Check Enable IGMP Snooping and
click Apply to invoke this function.
If the PVC you're using is NAT
enabled, remember to turn on the
IGMP Proxy at the same time.
Please refer to Internet – IGMP
Proxy for more information.
Chapter 4: Web Configuration
Note that the IGMP proxy must be
enabled first. If the IGMP Snooping
function is not available as shown in the
following figure, you have to enable the
IGMP Proxy first.
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