Streaming Media Supplement sa2150 and sa2250

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Chapter 4 Understanding Media-IXT and WMT
Beyond simple forward proxy, reverse proxy, and transparency for WMT
This section describes three scenarios that have special configuration requirements for deployments which
stream WMT content.
Simultaneous forward and reverse proxy caching for WMT
For WMT, Media-IXT can:
• perform forward proxy and reverse proxy simultaneously,
- OR -
• be restricted to perform forward proxy exclusively,
- OR -
• be restricted to perform reverse proxy exclusively.
This is controlled by the combination of two variables, proxy.config.reverse_proxy.enabled and
proxy.config.url_remap.remap_required.
The following table summarizes the possibilities for WMT. Aside from setting the desired variables, you must
add the correct map and reverse_map rules to remap.config if you wish to enable reverse proxy
caching.
Configure both variables in a given column to achieve the effect described by the heading of that column.
Exclusive reverse proxy configuration for WMT
WMT streaming uses both HTTP servers, where WMT metafiles reside, and WMT origin servers, which host
WMT streaming content files. This section concerns the case where:
• Media-IXT is deployed for reverse proxy, and
• an HTTP server which Media-IXT does reverse proxy has links to WMT streaming content files on an
origin WMT server that Media-IXT does not reverse proxy.
Here is an example of how and why this could happen:
First, we assume that reverse proxy is enabled.
Secondly, the HTTP server is accounted for in remap.config, so it is being reverse proxied; it probably has
some links to WMT content on origin WMT servers which Media-IXT does proxy.
Finally, the Traffic Server config variable proxy.config.url_remap.remap_required in
records.config is set to true (1). This means that unless there is a remapping rule for a URL in
remap.config, Media-IXT does not rewrite that URL.
When a client sends a request for a WMT metafile which contains a streaming content URL for the origin WMT
server that Media-IXT does not reverse proxy, Media-IXT sends the WMT metafile file back to the client
without altering the streaming content URL. The client then contacts the origin WMT server correctly, without
involving Media-IXT.
About server farms There is no need for special treatment for servers behind a load-balancing
switch.
Variables
Forward
proxy
caching only
Simultaneous
forward and reverse
proxy caching
Reverse
proxy
caching only
proxy.config.reverse_proxy.enabled false true true
proxy.config.url_remap.remap_
required
false false true