Streaming Media Supplement sa2150 and sa2250

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Chapter 5 Understanding Media-IXT and QuickTime
Understanding forward, explicit proxy caching for QuickTime
In explicit caching, end users must configure their QuickTime Players to send requests directly to a proxy cache,
namely the Media-IXT host.
Forward, explicit proxy caching works like this for QuickTime content:
1. A QuickTime Player client sends a request to Media-IXT, normally on port 1091.
2. Media-IXT opens a TCP connection to the origin QuickTime server, dedicating the connection to the client
which sent the request.
3. Media-IXT determines whether the requested content is in cache, and whether it is fresh.
If the content is in cache but stale, or is not in cache, Media-IXT pulls the requested content from the origin
QuickTime server, and caches the content (if cacheable).
If the content is in cache and is fresh Media-IXT does not need to pull the content from the origin server.
4. Media-IXT streams content to the QuickTime Player client, normally over UDP.
Understanding forward, transparent proxy caching for QuickTime
Transparent, forward proxy caching for the HTTP and NNTP protocols is described in the HP Cache Server
Appliance Administrator Guide. For RTSP, which QuickTime uses for transparent, forward proxy caching,
works a little differently.
For an explanation of transparency devices (layer 4 switches and WCCP2 routers) see Chapter 2‚ Media-IXT
Deployment Scenarios.
The relevant Media-IXT components are:
• the Traffic Server cache
• the Adaptive Redirection Module (ARM)
These general principles apply:
Figure 5-1. QuickTime forward proxy caching example
Me ia-IXTd
Origin
QuickTime
ser v er
Client brow ser w ith QuickTime Player
1
rtsp
port
1091
4
udp
2
tcp
3
A QuickTime Player client sendsa request to Media-IXT, normally on port 1091.
Media-IXT opens a TCP connection to the origin QuickTime server.
Media-IXT det ermines w hether t he request ed content is in cache, and whether it isfresh.
The content isin cache and is fresh, so Media-IXT does not need to pull the content from
the origin server.
Media-IXT streamscontent to QuickTime Player.
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2
3
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