Scenario: Deployment with a Windows Media server

About this scenario

This scenario provides two examples of the deployment of a streaming media cache and a Windows Media streaming server. In both examples, the deployment is nontransparent; that is, no L4 or L7 switch, WCCP router, or policy-based router is deployed to pass requests to the streaming media cache. Instead, Windows Media metafile rewriting is used to pass requests to the streaming media cache. The scenarios in this section illustrate the use of Windows Media metafile rewriting in two nontransparent streaming media deployments.

Network Appliance recommends deploying streaming media service by using transparent proxying.

Note
An alternative to the deployment examples in this scenario is described in Scenario: ISP adding streaming media caches and Scenario: Distributed streaming media caches for RTSP-based transparent streaming.

Windows Media metafile rewriting enables the request to be sent to the cache

Streams on a Windows Media server running are contained in one of a few types multimedia files--.asf, .wmv., or .wma. A text file (.asx, .wmx, or .wax) acts as a link from a Web page to the .asf, .wmv., or .wma file on a Windows Media server. Clicking an .asx, .wmx, or .wax file link on a Web page transfers control of the data from the Web browser to the Windows Media player so that the data can stream. An example of an ASX file follows:

<asx version = "3.0"> <ref href = "mms://server/content/movie.asf"/> </asx>

For a streaming media cache to be able to intercept a nontransparent MMS streaming request when transparent proxying is not deployed, the origin address in the text file must be changed to the address of the cache.

The NetCache Windows Media metafile rewriting feature, used for a nontransparent streaming media deployment with a Windows Media server, prepends the IP address of the streaming media cache to the origin address.

After NetCache applies Windows Media metafile rewriting to the previous ASX file, the following entries are displayed.

<asx version = "3.0"> <ref href = "mms://streaming-cache-ip/server/content/movie.asf"/> <ref href = "mms://server/content/movie.asf"/> </asx>

Note
The NetCache Windows Media metafile rewriting feature is necessary for Windows Media media players prior to version 7 but can be used with later versions.

About the company in this scenario

ABC, Inc., is a small company with offices that are close geographically. Currently, the company has one NetCache appliance running as a Web cache. Client browsers are manually configured to point to the Web cache; the company is not interested in using transparent proxying for client access to the NetCache appliance.

The managers are interested in providing their employees with access to streaming media. They have purchased a Windows NT server that is to function as a Windows Media streaming server.

Company requirements

The company's requirements are as follows:

Provide good quality streaming media presentations
Protect the streaming server from becoming overloaded with too many connections
Do not add any network hardware other than a NetCache appliance and the Windows Media server.

Providing client access to the streaming media cache

The key points to understand about setting up a nontransparent deployment with a Windows Media server are as follows:

The streaming request must be sent to a Web cache first.
Windows Media software prior to version 7 does not provide any way to point a Windows Media media player to a cache. Therefore, in a nontransparent streaming media deployment with a Windows Media server, client Web browsers must be configured to point to the Web cache.
The Web cache must pass the streaming request to the streaming media cache.
The Web cache must rewrite the origin server address to that of the streaming media cache so that the streaming request can reach the cache. The Web cache rewrites the address through Windows Media metafile rewriting.
You must configure the information that the Web cache needs to rewrite the origin server address to that of the streaming media cache.
Windows Media metafile rewriting works whether you are deploying a single NetCache appliance configured to run as both a Web cache and a streaming media cache or whether you are deploying a dedicated streaming media cache.
Configuration is slightly different in these two types of deployments, as described in the examples in the following section.

Note
Network Appliance recommends deploying dedicated NetCache appliances. However, small organizations might find that one NetCache appliance can handle the traffic for multiple protocols.

Deployment examples illustrated

This section contains the two examples of nontransparent streaming media deployments in which a Windows Media server running pre-version 7 software is deployed, as follows:

Example 1 shows a NetCache appliance that is configured as both a Web cache and a streaming media cache.
Example 2 shows one NetCache appliance deployed as a dedicated Web cache and another NetCache appliance deployed as a dedicated streaming media cache.

Example 1: a single NetCache appliance configured as both a Web cache and a streaming media cache

In the following example, client browsers are configured to point to the Web cache, which in this case is on the same NetCache appliance as the streaming media cache.

In the preceding example, notice that NetCache handles the HTTP and MMS protocols separately. The Web cache side of the NetCache appliance must communicate with the Web server to obtain the ASX file that NetCache needs to translate the origin server address of the streaming server to the origin server address of the streaming media cache.

After the Web cache rewrites the origin server address, the Web browser passes the request to the Windows Media player on the client, which then passes the request to the streaming media cache. The streaming media cache connects to the Windows Media server for any requested streams that it is not already delivering.

Example 2: dedicated NetCache appliances

The following example shows two dedicated NetCache appliances. One is configured as a Web cache and the other is configured as a streaming media cache.

As in Example 1, client browsers must be configured to point to the Web cache. The handling of the request from the Web cache to the streaming server is exactly the same as the process described in Example 1. The difference between this example and Example 1 is where you configure Windows Media metafile rewriting. In this example, you must configure Windows Media metafile rewriting on the dedicated Web cache. Doing so enables the Web cache to rewrite the IP address of the streaming server to the IP address of the dedicated streaming media cache.