Best Bandwidth Solution(s) For Video ?

I was recently asked the following: What Are The Best Bandwidth Solution(s) For Video Conferencing & Multi-Media Applications? What bandwidth solution (T1, DS3, OCx/Sonet, etc.) would you recommend for a small, medium, and large size business ... and why .... to cover videoconferencing and multi-media applications? No other specifics to offer ...Rather I want your thoughts and recommendations for what a company should plan to (small, medium, and large).

All I could rake up from the depths of the foggyness of my mind is the following: Without knowing the specifics, it is hard to provide a precise answer, but, one can still grope around for a systematic method for calculating required bandwidth. Once you know the bandwidth requirement, then it is all about the balancing act between budget restrictions and providing the required performance. Rule of thumb, as I know it is as follows:

1. Calculate the peak external link bandwidth requirements (inter-office data transfer, video conferencing, email transfers. With attachments running in tens of megabytes, email traffic can’t be ignored these days.).

2. Real time applications being most jitter and delay sensitive - so you have to make sure that you will have enough bandwidth when they need it. The bandwidth of video depends on the mpeg profiles used (without going into specific, generally 1.5 Mbps can give you very good video on a PC (equal to VCD quality). HDTV images can take about 20 Mbps – but that is domain more reserved for IP TV service providers). Most current users of interactive video communications will be happy with the images coded and transmitted @ 512 Kbps. This includes audio and video as well as control signaling. So, one should provision at least 512 Kbps per video stream, and more the better (I would say 1.5 Mbps is the good if you are a big organization and use a large TV for video conferences)). So, multiply bandwidth for a single stream with number of parallel streams required. Now that determines the total peak real time usage.

3. There is no specific rule but wise men with experience advise to keep the peak real time within 60 to 75% of network bandwidth available leaving remaining capacity for background traffic. In a small organization of 5 people - it is easy to tell people not to download gigabyte attachments when video conferencing is going on , but in larger organization it is hard to enforce such things except with router policies (assuming they have QoS support), and you can deal with occasional unhappy users.

4. Now, once you know your bandwidth requirements, it is time to talk to the network operator how they can provide that bandwidth in the most cost effective way.

I'd say it also dedends on what kind of service and QoS you are looking at. For example, when you say "video" I suppose you mean video conferencing and not something like VoD. The Bandwidth requirements will vary according to your service requirements.

For example: For IPTV services, the image quality depends on the encoding deployed: MPEG-2 consumes approx. 3.75 Mbps, whereas MPEG-4 needs approx. 2 Mbps for the same high-quality image production. Also broadcast TV is delivered using IP Multicast which makes the bandwidth required dependent on the number of channels offered and the encoding rate. 200 channels of MPEG-2 in standard definition will take approx. 750 Mbps of bandwidth. VoD, on the other hand, is a unicast per-viewer channel. 1000 standard definition VoD users will need appro. 3.75 Mbps.

The QoS requirements for video conferencing using H.323 ( SIP could be different again) can be planned on the "Rule of 75" as follows: Calculate the minimum bandwidth required b each of your application( e.g., video, voice, data). The total of this badnwidth is the minimum requirement for any given link and it should consume NO MORE than 75% of the total available bandwidth on the link. The 75% rule makes allowances for bandwidth required for over head traffic, such as routing, Layer 2 keepalives and other applications, such as, email, HTTP etc.

So, Capacity planning for H.323, should look like something as follows:

Video data + 20% = bandwidth required.

Example Video data rate: Bandwidth Required: 512 kbps = 614 kbps ; 1.5Mbps = 1.8 Mbps ...

For issues such as number of concurent users and more stuff on video conferencing you can perhaps consider looking into Cisco's solutions offered and also TANDBERG boxes.