Architecture of WTJU Streaming Service

[Nov 23, 2009 14:09] Web access to Microsoft Live@edu accounts now works.

This page is a description of the WTJU streaming architecture, including an explanation of network multicasting.

This system was built using Dell computers and the Microsoft Windows Media Encoder and the Microsoft Windows Media component of the Windows 2003 Server operating system.

The operating system on the encoder PC is Windows XP Pro. The server for on-grounds uses multicast, so the Enterprise version of Windows Server 2003 had to be used. The unicast server for off-grounds uses the standard version.

Equipment requirements are listed on the Microsoft site. Systems using Real Networks software or QuickTime software can be constructed to accomplish the same sort of service.

Diagram of WTJU service

The WTJU signal is fed into a Creative SoundBlaster PCI card and encoded by the Windows Media Encoder software. The high bandwidth stream is made available on one port, whule the lower bandwidth stream is made available on another. The on-grounds server, wtju-l.eservices.virginia.edu, is accessible only by machines on the local UVa network. The off-grounds server, wtju–r.eservices.virginia.edu, can be accessed by a machine on any network.

Multicast vs Unicast

A unicast connection is a standard client/server network connection. A dedicated stream of data packets is directed from the server to the client software. If there are 10 unicast clients, there are 10 streams of data leaving the server. A multicast connection includes intelligent routing hardware along the data path that will send only a single of stream of data along to the next router rather than sending duplicate streams.

Example 1 (below) : Multicast-enabled network. There are eight clients on a network where all five routers have been enabled for multicast. The server only transmits one stream of data for these eight clients.

Multicast Diagram

Example 2 (below) : Mixed multicast/unicast network.Two of the eight clients are attached to the network via a router without the ability to multicast. Those clients each require a stream of data from the server. The server must provide three streams of data to serve eight clients.

Mixed multi- and unicast

The on-grounds server is configured to multicast whenever possible. When a multicast connection is not possible, a unicast connection is established. This conserves network bandwidth.

 

© 2009 by the Rector and Visitors of the University of Virginia.

The information contained on the University of Virginia’s Department of Information Technology and Communication (ITC) website is provided as a public service with the understanding that ITC makes no representations or warranties, either expressed or implied, concerning the accuracy, completeness, reliability or suitability of the information, including warrantees of title, non-infringement of copyright or patent rights of others. These pages are expected to represent the University of Virginia community and the State of Virginia in a professional manner in accordance with the University of Virginia’s Computing Policies.