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IPTV Technical Info
Network Requirement
To be suitable for IPTV operation, your data network must meet the following requirements:- Backbone bandwidth requirement is calculated as the number of channels streamed x bandwidth per channel. Typically channels are streamed at 4 Mbps each for MPEG2. eg for 12 channels the total bandwidth requirement on the backbone is 12x4= 48Mbps.
- At least one network switch is required to have IGMP Querier functionality.
- All switches must be multicast enabled- IGMP V2 capability
- All switches must be capable of using PIM (Sparse & Dense mode) if VLAN routing is to be implemented
- The network equipment should be capable of running QoS if other traffic on the network is likely to threaten the real time delivery of the IPTV data streams
- Static IP addresses are preferred for the IPTV equipment. A 100Mbps port is required for each MPEG2 encoder and 3x 100Mbps ports are required for a TV Gateway.
IPTV Benefits
IPTV leverages the investment in your data network to produce a TV and video reception and distribution solution with an unmatched combination of scalability, flexibility and value. Distributes live or prerecorded TV and video/audio over existing data networkUnlimited distribution to every network connected TV / PC
Capacity for hundreds of TV and video sources
Digital quality consistent across all viewing points
Managerial control over individual viewing
Flexible, controllable signage and corporate branding
No additional hardware, cabling or power required at PC viewing points
Office moves and changes become simple, quick and non technical
No distance limitations on viewing points
Dispenses with Freeview Set Top Boxes and video recorders
Manageable bandwidth requirements
Does not compromise network security
Industry standards based
Highly modular and readily expandable at any stage
Space saving professional equipment installation
Facility for live or scheduled recording of live TV provides the functionality of a video recorder with hard disk storage (Personnal Video Recorder)
Costs, space and energy are saved by dispensing with Freeview Set Top Boxes, video recorders and even TVs where PC viewing is adopted
Distribute channels over WAN links for viewing at remote sites
Create your own Video On Demand library for training and reference
High Definition TV (HDTV) support
IPTV Multicasting
MulticastingInternet Protocol (IP) multicast is a bandwidth-conserving mechanism for reducing data network traffic by simultaneously delivering a single stream of information to thousands of recipients. Multicasting is fundamental to the implementation of IPTV. This is how it works.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.
IPTV and HDTV
As High Definition TV (HDTV) gains momentum in the UK with HD transmissions via Freesat, Klicktv IPTV distribution systems demonstrate their seamless transition to the new standard with an unmatched ability to deliver faultless, as broadcast, HD transmissions right to the TV screen.
When the same HDTV transmissions are broadcast on terrestrial Freeview (expected in 2012) the situation will be the same - a terrestrial IPTV gateway installed today has the capability to deliver terrestrial HDTV broadcasts when they arrive.
Because HD IPTV products can coexist with Standard Definition products within the same IPTV system, there is wide scope for the design of systems which offer the optimum cost/ benefit balance for a given requirement.
