Your business intends to make extensive use of video conferencing and multimedia applications. How do you determine what bandwidth solution (T1, DS3, OCx/Sonet, etc.) would best meet your needs and incorporate that decision into your network to cover these applications Your business intends to make expansive use of videotape conferencing and multi-media operations.
Determining and Integrating the Right Bandwidth Solution
How do you determine what band width result( T1, DS3, OCx SONET, etc.) would best meet your requirements and incorporate that decision into your network to cover these operations?
I’d say that it depends on what kind of service and QoS you’re looking at. For illustration, when you say” videotape” you mean videotape conferencing and not a commodity like VoD. The Bandwidth conditions will vary according to your service conditions.
For illustration For IPTV services, the image quality depends on the garbling stationed MPEG- 2 consumes approx.3.75 Mbps, whereas MPEG- 4 needs approx. 2 Mbps for the same high-quality image product.
Also, broadcast television is delivered using IP Multicast which makes the bandwidth needed to depend on the number of channels offered and the garbling rate. 200 channels of MPEG- 2 in the standard description will take approx. 750 Mbps of bandwidth.
VoD, on the other hand, is unicast per bystander channel. 1000 standard description VoD druggies will need appro.3.75 Mbps.
The QoS conditions for videotape conferencing using H.323( draft could be different again) can be planned on the” Rule of 75″ as follows Calculate the minimal bandwidth needed by each of your operations(e.g., videotape, voice, data).
The aggregate of this bandwidth is the minimal demand for any given link and it should consume NO further than 75 of the total available bandwidth on the link.
Capacity Planning and Bandwidth Allocation for H.323 and QoS
The 75 rule makes allowances for the bandwidth needed for overhead business, similar to routing, Subcaste 2 keepalives, and other operations, similar to, dispatch, HTTP, etc.
So, Capacity planning forH.323, should look like a commodity as follows
videotape data 20 = bandwidth needed.
Illustration
videotape data rate Bandwidth needed
512 kbps = 614 kbps
Mbps = 1.8 Mbps.
For issues similar to a number of concurrent druggies and further stuff on videotape conferencing you can maybe consider looking into Cisco’s results offered and also TANDBERG boxes.
Cisco considers anything 766Kb to be a” slow link” for VOIP. Also, you need to consider the criticality of the spots so you may need two separate connections. All multi-media operations run on top of your other operations so QoS only allows a preference of who goes first.
You need a good birth ofnon-multi-media operations( VOIP). So bandwidth needs to be suitable to handle all necessary operations in the network.
Also, you will need to a flashback that the bandwidth aggregation at the Data Center needs to meet or exceed all inbound remote point business. In other words, if I’ve three remote spots all with T1s. I will need further than one T1 at the Data Center to manage the business. Flashback unless this is a greenfield also birth, birth, birth!
Bandwidth Requirements for Streaming Video and Real-Time Operations
When it comes to streaming videotape, bi-directional- you’re going to have to consider the quality of the contraction you’re planning to use. If you’re planning on using high description videotape 1 direction it’s recommended to have at least 2 MB in the direction of the videotape being penetrated.
So if you’re streaming videotape to your computer also you need to make sure that you get 2 MB download capacity. Also, another thing to keep in mind is quiescence and loss of packets. I would recommend staying down from wireless for this type of operation as it’ll add quiescence and beget issues latterly. DS3 bandwidth and anything advanced may be overkill, but would fluently be suitable to handle your demands.
Without knowing specifics, it’s hard to give a precise answer, but, one can still specify a methodical system for calculating needed bandwidth. Once you know the bandwidth demand, also it’s all about negotiating the most provident way to order that bandwidth from a network provider in the area.
Then‘s what I would suggest
1. Calculate the peak external link bandwidth conditions(inter-office data transfer, videotape conferencing, dispatch transfers. With attachments running in knockouts of megabytes, dispatch business can not be ignored these days.).
2. Real-time operations are substantially jitter and detention sensitive– so you have to make sure that you’ll have enough bandwidth when they need it. The bandwidth of videotape depends on the MPEG biographies used( without going into specific, generally 1.5 Mbps can give you veritably good videotape on a PC( equal to VCD quality).
HDTV images can take about 20 Mbps but that’s sphere more reticent for IP television service providers). utmost current druggies of interactive videotape dispatches will be happy with the images enciphered and transmitted@ at 512 Kbps. This includes audio and videotape as well as control signaling.
So, one should provision at least 512 Kbps per videotape sluice, and the more the better( I would say 1.5 Mbps is good if you’re a big association and use a large television for videotape conferences)). So, multiply bandwidth for a single sluice by the number of resemblant aqueducts needed. Now that determines the total peak real-time operation.
3. There’s no specific rule– but wise men with experience advise to keep the peak real-time within 60 to 75 of the network bandwidth available leaving the remaining capacity for background business.
In a small association of 5 people- it’s easy to tell people not to download gigabyte attachments when videotape conferencing is going on, but in larger associations, it’s hard to apply similar effects except with router programs( assuming they’ve QoS support), and you can deal with occasional unhappy druggies.
4. Now, once you know your bandwidth conditions, it’s time to talk to the network driver about how they can give that bandwidth in the most cost-effective way.
Bandwidth Needs for Video and QoS Requirements
I’d say that it depends on what kind of service and QoS you are looking at. For example, when you say “video” 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 to depend 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 by each of your applications ( e.g., video, voice, data). The total of this bandwidth 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 overhead 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 …
Best Practices for Video Conferencing and Bandwidth Management
For issues such as the number of concurrent users and more stuff on video conferencing, you can perhaps consider looking into Cisco’s solutions offered and also TANDBERG boxes.
Cisco considers anything 766Kb to be a “slow link” for VOIP. Also, you need to consider the criticality of the sites so you may need two separate connections. All multi-media applications run on top of your other applications so QoS only allows a preference of who goes first.
You need a good baseline of non-multi-media applications (VOIP). So bandwidth needs to be able to handle all necessary applications in the network.
Also, you’ll need to remember that the bandwidth aggregation at the Data Center needs to meet or exceed all inbound remote site traffic. In other words, if I have three remote sites all with T1s. I’ll need more than one T1 at the Data Center to manage the traffic. Remember unless this is a greenfield then baseline, baseline, baseline!
When it comes to streaming video, bi-directional – you are going to have to consider the quality of the compression you are planning to use. If you are planning on using high-definition video 1 direction it is recommended to have at least 2MB in the direction in which the video is accessed.
So if you are streaming video to your computer then you need to make sure that you get a 2MB download capacity.
Also, another thing to keep in mind is latency and loss of packets. I would recommend staying away from wireless for this type of application as it will add latency and cause issues later. DS3 bandwidth and anything higher may be overkill, but would easily be able to handle your demands.
Without knowing specifics, it is hard to provide a precise answer, but, one can still specify a systematic method for calculating the required bandwidth. Once you know the bandwidth requirement, then it is all about negotiating the most economical way to order that bandwidth from a network provider in the area.
Here is what I would suggest:
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 are mostly 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 specifics, 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 a 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 the more the better (I would say 1.5 Mbps is good if you are a big organization and use a large TV for video conferences)). So, multiply the bandwidth for a single stream by the 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 the 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 organizations, 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 about how they can provide that bandwidth in the most cost-effective way.
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