Streaming Media Supplement sa2150 and sa2250

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Chapter 3 Understanding Media-IXT and RealNetworks
If the content is in cache and is fresh, Media-IXT streams content to RealPlayer, and does not need to pull
the content from the origin server.
Beyond simple forward proxy, reverse proxy, and transparency for RealNetworks
This section describes three scenarios that have special configuration requirements for deployments which
stream RealNetworks content.
Server farms
Several origin servers with some sort of load balancing device, like a layer 4 switch, between them and the
Internet, is a popular form of the server farm.
Media-IXT’s way of communicating with origin RealServers uses the port and IP address information
representing the origin RealServer in such a way that the server farm’s layer 4 switch can disrupt
communications.
Where Media-IXT and the origin RealServers are owned by two different entities, as is the case with most
forward proxy deployments of Media-IXT, there is no fix for this problem.
Figure 3-4. RealNetworks reverse proxy caching example
Me ia-IXTd
http://reallygreatmovies.com/
Client brow ser with
RealPlayer
6
1
rtsp://greatmovies.com:554/epic.rm/.
1
2
3
4
5
6
2
http://www. greatmovies .com/
5
tcp
3
4
rtsp://reallygreatmovies.com:554/epic.rm/
media content URL
rtsp://greatmovies.com:554/epic.rm/
+
map rule:
map rtsp://greatmovies.com/ rtsp://reallygreatmovies.com/RNI
=
rewritten URL:
rtsp://reallygreatmovies.com:554/epic.rm/
Origin
RealServer
map rule locating the origin RealServer:
map rtsp://www.greatmovies.com/ rtsp://www.reallygreatmovies.com/RNI
RTSP request for:
rtsp://greatmovies.com:554/epic.rm/
The RealPlayer sends an RTSP request containing the URL
Media-IXT finds the hostname of the origin RealServer in the map rules contained in
the remap.config configuration file.
Media-IXT rewrites URLs in the client request, replacing the advertised site name with the host-
name of the origin RealServer. Our example URL is rewritten:
Media-IXT opens a TCP connection to the origin RealServer at the rewritten URL.
Media-IXT determines whether the requested content is in cache, and whether it is fresh.
The content is in cache and is fresh, so Media-IXT does not need to pull the content from
the origin server.
Media-IXT streams content to RealPlayer.