Streaming Media Supplement sa2150 and sa2250

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Chapter 5 Understanding Media-IXT and QuickTime
• Traffic Server’s role is transparent readdressing, proxying, and caching.
• QuickTime Players, like RealPlayers, use RTSP as the control protocol, so they direct RTSP requests to port
554.
• With transparency enabled, Media-IXT redirects QuickTime traffic from port 554 to its QuickTime RTSP
port, which is port 1091.
Here is how forward, transparent proxy caching for QuickTime plays out step by step:
1. A QuickTime Player client sends an RTSP request addressed to the origin QuickTime server on port 554.
2. The layer 4 switch or WCCP2 router intercepts the port 554 traffic and redirects it to Media-IXT.
3. Media-IXT redirects the request internally to port 1091.
(If the request is from a RealPlayer, Media-IXT issues a redirect to the player, so that the player then
communicates with Media-IXT’s RealProxy component on port 9231.)
4. Media-IXT opens a TCP connection to the origin QuickTime server, dedicating the connection to the client
which sent the request.
5. 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 the content is in cache and is fresh Media-IXT does not need to pull the content from the origin server.
6. Media-IXT streams content to the QuickTime Player client over UDP.
Figure 5-2. QuickTime transparent proxy caching example (beginning)
Me ia-IXTd
L4 Sw i t ch
Client brow ser with QuickTime player
rtsp
2
1
A Qui ck Tim e Pl ayer cl
l
ient sends an RTSPrequest addressed to the origin QuickTime Server on port 554.
The ayer 4
switch interceptsthe port 554 traffic and redirectsit to
Media-IXT.
M edia-IXT redirects t he request internally t o port 1091.
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2
3
Origin
QuickTime
ser v er
port
554
port
1091
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