| Network Recommendations This guidance is designed to help you configure your local area network, wide area network, and internet connectivity to achieve high quality video communication between classrooms. It is highly recommended that you consider the best solution to provide students and teachers a high quality video learning environment. Opting for the least expensive solution may not always be the best solution. The end users must be considered first when building your network. Latency, jitter, packet loss and delay on network connections add up and can degrade the end to end video session reducing the quality and usability of your session. Many different connectivity solutions are available to you from the State of North Carolina, large Telcos , and smaller LEA internet service providers. Videoconferencing applications require a network with few errors optimum conditions in order to transmit high quality video. Ideally, if you use a video conferencing classroom to provide distance learning you should strive to optimize your network for video conferencing. Data transmission through your network will also operate more efficiently if your network is optimized. So you gain not only high quality video transmission but higher quality data transmission by building a more complex and manageable network infrastructure. For the purpose of this discussion and to aid in understanding we need to separate the two types of services that you may be purchasing from network providers. The Circuit Provider First, to connect your site to the rest of the world you will need a circuit terminated at your site. This connection is typically provided by a local telephone company or broadband cable company. This is the copper or fiber connection that allows your site to connect to other sites and to the internet service provider. Circuits are offered by local regional telephone companies and broadband providers, large Telcos and broadband providers, and the Office of Information Technology Services, among others. The Internet Service Provider Secondly, there will have to be an internet service provider that will supply your site with a gateway to the internet. The company that provides the circuit into your site and that provides the Internet gateway connectivity may or may not be the same company. Typically, smaller localized telephone and broadband companies lease internet services from larger companies that have a nationwide internet backbone. This means that a session over the internet may have to pass through many facilities and (hops) to get to the internet and then with a video session, ultimately to ITS. Larger Telco’s and broadband providers may be able to also provide internet access. These larger companies may have their own internet backbone and would not have to lease connectivity from another company. The Office of Information Technology Services for the State of North Carolina offers both a circuit to connect your site to the states network and internet service to connect your site to the states network and the worldwide internet. A managed service is available and is recommended. Selecting the Circuit Provider. In your geographic area there is usually one Telephone Company that can provide your sites circuit or (last mile) connectivity. Today you also have the choice of selecting a broadband company that serves your area who can also provide connectivity to your site. Currently some Telcos and broadband providers offer a basic service or an enhanced or managed service between your site and other local sites or to the internet. In Option 1 diagram below we show a managed service which gives each site Quality of Service and VLAN capability. It is important to be aware of the level of service your provider can guarantee when purchasing site connectivity. Usually an enhanced or managed service is more complex, more reliable, and therefore more costly. When ordering your site's connectivity you should always analyze your total bandwidth requirements and ensure that you order adequate bandwidth for future growth. For a site that utilizes both video and data bandwidth pay careful attention to the potential peak usage during busy times of the day. You should always add a buffer of at least 20 percent above your peak estimated simultaneous bandwidth usage of both video and data at your site. Selecting Internet Service Providers. The internet service provider is one of the most critical parts of your network configuration. This network component can make or break a real-time video session. Implementing a lower cost solution will mean that your video session may have to traverse many hops or links prior to packets arriving at their destination. It is important to find out if the company that provides your circuit connectivity can also supply the internet gateway connection. If not then they will more than likely be able to lease internet access and resell it to you. This is where it is important to know what level of service they can provide to your site. A more managed solution can help to reduce the number of hops used between source and destination. An enhanced solution with quality of service can reduce the adverse conditions associated with best effort data transmission. When purchasing internet connectivity from a local Telco or broadband provider they should be able to provide a rough description of how many links (hops) you will be traversing on average with any internet video session. Some trace routes that have been performed from the ITS video bridge out to sites that have private ISPs have shown as many as 25 to 30 hops between the source and destination. This means that between your videoconferencing system and the ITS video bridge your session packets may be traveling across the country before being sent Raleigh, North Carolina. These multiple hops introduce packet loss, delay, latency, and jitter into the end to end video session. The key is to minimize the number of hops between your site and the site you are calling. In the diagram below we recommend that for the highest possible level of quality and service for videoconferencing you consider a managed connectivity solution from ITS. This also includes a 24 x 7 Customer Support Center along with video centric technicians and engineers that understand your distance learning application. |
|
|
|
|
|
|