Hey Guys... How are you doing today ?
Ever wondered when our traditional broadcasting based television telecast system is working fine then why do we need IPTV ?? Why the whole world is going mad after this upcoming technology. Probably you might never had thought about this. Okie... lets talk about IPTV and roles of multicasting in this technology.
So, What is IPTV ?
IPTV (Internet Protocol Television) delivers television programming to households via a broadband
connection using Internet protocols. It requires a subscription and
IPTV set-top box, and offers key advantages over existing TV cable and satellite technologies. IPTV is typically bundled with other services like Video on Demand (VOD), voice over IP (VOIP) or digital phone, and Web access, collectively referred to as Triple Play.
Why do we need IPTV ?
Just because big guys like Cisco, HP, IBM, Avaya are developing a complete product range for this... Well thats not true...
Okie... In traditional broadcast based system, backend devices broadcast all the channels (Video streams) to your TV or set-top box, after which there is barely any bandwidth left to run any other value added services. Secondly typical broadcast network is a one way media streaming system, So there is no scope for interactive services, with IPTV we would be able to use multiple services like - Internet, TV, telephony, zigby etc on a single cable.
Okie... In traditional broadcast based system, backend devices broadcast all the channels (Video streams) to your TV or set-top box, after which there is barely any bandwidth left to run any other value added services. Secondly typical broadcast network is a one way media streaming system, So there is no scope for interactive services, with IPTV we would be able to use multiple services like - Internet, TV, telephony, zigby etc on a single cable.
Lets see how multicast (Instead of broadcast) helps us in conserving network bandwidth and allow us to use the same for other services (Thanks to Klicktv)-
In diagram 1, none of the network switches have IGMP snooping or
querying turned on and so the network is not multicast enabled. The
backbone switch has all the streaming traffic coming into it from the
MPEG IP Encoders. If we assume each stream is 4 Mbps the backbone
switch will carry 4 Mbps x 3 streams = 12 Mbps of streaming traffic.
As the switches don’t have IGMP turned on, the streaming
traffic will flood the entire network regardless of whether the user
requests a particular stream or not.
In diagram 2, all switches have IGMP snooping turned on and
the backbone switch has IGMP query turned on. Again, the backbone
switch has a total of 12 Mbps of streaming traffic coming into it from
the MPEG IP 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.
In calculating the bandwidth requirement for IPTV, it should
be assumed that all streams will be present on the backbone but, at
most, only one stream will be present on a user port.
Okie... i beleive this explains everything, Furthermore lets have a look at this brilliant video, explaining how the data would flow on IPTV network -
So guys, gear up for this latest and upcoming technology and enjoy multiple technologies on a single pair of cable.
Sayonara for now... We will catch you soon with another post on Fibre to Home Technology.
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