Becta have made some information about HD Video and its implications for network load etc… See the following link
This states that HD video requires about 1Gbps to transmit HD Video uncompressed in real time. There are of course compression techniques which reduce the bps required. In a school situation where it can be expected that there will be significant concurrent demands to consume HD resources as they become more available. The Glow project in Scotland is an example of a national Intranet for school users which could serve HD content. This content would be stored on a central server at the Glow Data Centre and would be accessible in any school in Scotland – and of course to users when accessing the service from home.
One essential link between the national data centre and the school is the link between the school and the Local Authority network. This could be anywhere between 2 and 100 Mbps in capacity. the uplink form a Local authority could be between 45 Mbps and 1Gbps. Clearly many concurrent streams of even compressed HD video could result in these links becoming congested to the extent that the network will slow down greatly. One strategy to overcome this problem for the Local Authority to block video traffic – and there are certainly some LAs that will already have implement such a traffic policy.
One has to reflect on the impact that this will have on the underlying network as use of HD video starts to take of. I am of the view that school users will want to use HD video resources to enhance the current range of online resources which are available for teaching and learning! Imagine the possible impact when lots of people, pupils and teachers using their Flip camera to capture HD video and then sharing them online!
One technology which can provide some essential support in this context is to implement a Content Delivery Network. This is a series of devices with one positioned in each school which has the facility to have HD assets pre-positioned on a built in disc during periods of low network usage – such as over night. If this is the case, each time a user in the school accesses a HD video and it has been pre-positioned on the local content engine, the video will be served via the schools Local Area Network. Which can be based on Gigabit Ethernet technology!
Thankfully the Scottish Government had the fore-sight a number of years ago to invest in such a network for all of Scotland schools which has the capability to pre-position network based content which cannot be delivered in real time. Of course it is also possible to increase the capacity of the network elements but I would suggest that this is a less viable strategy in view of the fact that wide area bandwidth still comes at a relativity high cost.