Streaming Media Supplement sa2150 and sa2250

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Chapter 4 Understanding Media-IXT and WMT
Understanding selective caching and WMT
Using selective caching, you can specify criteria to determine whether content is proxyable or not, and
cacheable or not.
When content is not proxyable, Media-IXT denies the client connection, with an appropriate message to the
client (if possible).
When content is not cacheable, Media-IXT goes into passthrough mode and proxies, but does not cache, the
content.
See the HP Cache Server Appliance Administrator Guide for more information about selective caching.
Two configuration files control selective caching:
• cache.config controls cacheability
• filter.config controls proxyability
You must edit cache.config and filter.config manually, adding selective caching rules to the files.
Always use hostnames (in Fully Qualified Domain Name form), not IP addresses, in selective caching rules.
Rules containing IP addresses are likely to be ignored by Media-IXT.
Understanding authentication and WMT
Of the two types of authentication, LDAP authentication is not supported for WMT streaming.
Proxy authentication through to origin server.
Media-IXT passes the origin server’s challenge to the client,
and passes any response from the client back to the origin server. Then Media-IXT passes traffic between client
and origin server without modification, and without writing the content to cache. In effect, Media-IXT treats
the content in passthrough mode.
In a hierarchical deployment, Media-IXT passes authentication data to the upstream Media-IXT, which in turn
passes it on to the origin server.
Likewise, when configured for reverse proxy, Media-IXT passes authentication to the backing origin server.
The reverse proxy configuration determines the backing origin server; no special configuration is needed for
authentication.
Understanding firewalls and WMT
Media-IXT is being used, at various sites
• with both application-level and network-level firewalls,
• in explicit and transparent forward proxy deployments,
• for RealNetworks, WMT, and QuickTime streaming formats,
• for both on-demand and live content.
Some deployments use both an application-level and a network-level firewall (running on separate hosts) with
Media-IXT. Note that the popular Gauntlet Firewall v5.5 can run both as an application-level firewall (proxy
mode), and as a packet filter (packet filter mode).
See “Understanding firewalls” on page 16.
That said, firewall support as a Media-IXT feature is still under development. Streaming WMT content across
a firewall has not been tested and is not supported by HP for Media-IXT 4.x.
Media-IXT always uses TCP as the underlying transport protocol between itself and an origin WMT server for
splitting of live streams. So, UDP packets not being permitted through the firewall is not necessarily an issue
for WMT streaming across a firewall.