KYLAND Technology SICOM3024P, Web Operation Manual

Page: 61 / 147

Advanced Configuration
54
6.8.5 Typical Configuration Example
As shown in the following figure, IGMP Snooping is enabled on Switch 1, Switch 2, and
Switch 3. Auto query is enabled on Switch 2 and Switch 3. The IP address of Switch 2 is
192.168.1.2 and that of Switch 3 is 192.168.0.2.Therefore, Switch 3 is elected as the querier.
1.Enable IGMP Snooping on Switch 1.
2.Enable IGMP Snooping and auto query on Switch 2.
3.Enable IGMP Snooping and auto query on Switch 3.
Figure 56 IGMP Snooping Configuration Example

Switch 3 as the querier periodically sends general query packets. Port 4 of Switch 2
receives the packets and is thus elected as the routing port. Switch 2 forwards the packets
through port 3. Then port 2 of Switch 1 receives the packets and is thus elected as the
routing port.

When PC 1 is added to multicast group 225.1.1.1 and sends IGMP report packets, port 1
and port 2 (routing port) of Switch 1 are added to multicast group 225.1.1.1. IGMP report
packets are forwarded to Switch 2 through port 2. Then port 3 and port 4 of Switch 2 are
also added to multicast group 225.1.1.1. Switch 2 forwards the report packets to Switch 3
through port 4. As a result, port 5 of Switch 3 is also added to multicast group 225.1.1.1.

When receiving multicast data, Switch 1 forwards the data to PC 1 through port 1. As port
2 is also a multicast group member, it also forwards multicast data. As the process
proceeds, multicast data finally reaches port 5 of Switch 3 because no further receiver is
available. If PC 2 is also added to multicast group 225.1.1.1, multicast data is also
forwarded to PC 2.