Streaming Media Supplement sa2150 and sa2250

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Chapter 8 Configuring Media-IXT for WMT
See the description of url_regex in the section about filter.config above; use of url_regex with
cache.config works the same way.
In the example below, the rule allows WMT content from 11.11.11.11 to be cached.
dest_ip=11.11.11.11 scheme=mms action=standard-cache
Differences between forward and reverse proxy selective caching
For a reverse proxy deployment, selective caching rules must be written differently than for a forward proxy
deployment. That is because rules must be based on requested URLs after remapping has been applied. In a
forward proxy clients request the origin server hostname. In reverse proxy clients request the advertised name
of the website, which Media-IXT then remaps to the origin server hostname. Observe the differences in the two
examples that follow.
A forward proxy cache.config example
Here is an example rule:
dest_ip=11.21.31.41 scheme=mms action=never-cache
This rule prevents Media-IXT from caching WMT content hosted on the origin server whose IP address is
11.21.31.41.
A reverse proxy cache.config example
Here is an example rule:
dest_ip=11.21.31.41 scheme=mms action=never-cache
Let us assume that:
• the advertised name of the website is foo.bar.com;
• Media-IXT answers requests for foo.bar.com at 55.55.55.55
• Media-IXT performs reverse proxy for the origin server back.door.com, whose IP address is
11.21.31.41.
What happens to make this rule work?
1. The Windows Media client sends a request for content at the advertised website name, foo.bar.com,
which resolves to 55.55.55.55;
2. Media-IXT answers the request, remapping 55.55.55.55 to 11.21.31.41, the origin server
according to its rules in remap.config;
3. Media-IXT applies cache.config to the request after remap.config has been applied; the rule
matches the destination IP address in the request, which is 11.21.31.41;
4. Media-IXT, following the rule, does not cache content hosted on 11.21.31.41.