Streaming Media Supplement sa2150 and sa2250

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Chapter 3 Understanding Media-IXT and RealNetworks
Understanding forward, explicit proxy caching for RealNetworks
Media-IXT supports forward, explicit proxy caching for both RTSP and PNA content.
In explicit caching, end users must configure their RealPlayers to send RTSP or PNA requests directly to a
proxy cache, namely the Media-IXT host. Media-IXT receives these requests through its RealProxy component.
Forward, explicit proxy caching works like this for RealNetworks RTSP content:
1. A RealPlayer client sends a request to Media-IXT, normally on port 1091.
2. Media-IXT opens an accounting connection to the origin RealServer, dedicating the connection to the client
which sent the request.
3. If the client is allowed access, Media-IXT opens a TCP connection to the origin RealServer.
4. If not, Media-IXT closes the accounting connection and returns an error to the client; the remaining steps
do not apply in this event.
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
RealServer, 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 RealPlayer client.
Figure 3-1, below, illustrates forward, explicit proxy caching for RealNetworks RTSP content.
Forward, explicit proxy caching for RealNetworks PNA content works the same way, but the port to which
RealPlayer sends its requests is normally port 1090.
Understanding forward, transparent proxy caching for RealNetworks
Forward, transparent proxy caching is supported for both RTSP and PNA content.
Figure 3-1. Forward, explicit proxy caching for RealNetworks
Origin
Re al Se r v e r
with cache plugin
P
L
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G
I
N
1
5
2
3
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RealPlayer sends a request t o M edia-IXT on port 1091.
Media-IXT opensan accounting connection to the origin RealServer.
This client isallowed access, so
p
g
Media-IXT o ens a TCP connect ion t o t he ori in RealServer.
Media-IXT determineswhether the requested content is in cache, and whether it isfresh.
The content isin cache and isfresh, so
Media-IXT doesnot need to pull the content from
the origin server.
M edia-IXT streams cont ent to RealPlayer.
1
2
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4
5
Me ia-IXTd
rtsp
port
1091
accounting
tcp
udp
Client browser with RealPlayer