User Manual
Scion Tech
SC08.MX2000
Tel: +44 (0) 1635 862484
www.scion-tech.co.uk
Page 11
In
Diagram 2
, all switches have IGMP snooping turned on and the backbone switch has IGMP query
turned on and the network is multicast enabled. Again, the backbone switch has a total of 12 Mbps of
streaming traffic coming into it from the IPTV Encoders.
Switch 1 will only have 8 Mbps of traffic reaching it as a result of the two users who have requested the
same red stream (4 Mbps) and a third user who has selected the green stream (4 Mbps). This is the
distinct advantage of multicasting - the bandwidth used is per stream and not per user.
Switch 2 will only have 4 Mbps of traffic reaching it since only the blue stream has been requested by a
user. There will be no streaming traffic on the port where there is no request for a stream. Switch 3 will
have no streaming traffic since none of the users connected to the switch have requested any streams.
Encoders
Core Switch
Switch 3
Switch 2
Switch 1
Decoders
Diagram 2
