Specifications

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Cisco Internet Streamer CDS 2.0-2.3 Software Configuration Guide
OL-13493-04
Chapter 1 Product Overview
Content Delivery System Architecture
Service Router
The Service Router mediates requests from the client devices and redirects the requests to the most
appropriate Service Engine. It monitors the load of the devices and does automatic load balancing.
The Service Router is the authoritative Domain Name System (DNS) server for the routed request for
the Fully Qualified Domain Name (FQDN) of the origin server. In other words, the Service Router
responds to any DNS queries for that domain. The Service Router chooses the Service Engine based on
two scenarios:
• Client is directly connected to the service provider’s network (on-net).
• Client is roaming outside the home network (off-net).
When clients are connected to the service provider’s network, the Service Engine is chosen based on the
requested FQDN, the client’s IP address, and the responsiveness of the Service Engine. The Service
Router compares the source IP address of the client against a table of address ranges assigned to the
Service Engines, known as the Coverage Zone file. The Coverage Zone file provides information on the
proximity of the client to the Service Engine based on each client’s IP address.
If the client is not connected to the service provider’s network and location-based routing is enabled, the
Service Engine that is geographically closest to the client is selected. The Service Router uses a
Geo-Location server to find the geographical location of the client. Geographical distance is calculated
between the client and the Service Engine. The closest Service Engine is chosen based on the distance.
IP-Based Redirection
Note IP-based redirection is a Release 2.3 feature.
In Release 2.3, there are two ways for client requests to get routed to the Service Router and on to the
Service Engine:
• Router Fully Qualified Domain Name (RFQDN) redirection
• IP-based redirection
RFQDN redirection is the default configuration. With RFQDN redirection, client requests are resolved
to the Service Router by the DNS server and the Service Router redirects the request to the Service
Engine based on route tables created from the Coverage Zone file and the current load of the Service
Engines. The redirected URL is http://SENAME.SE.RFQDN/relative_path_of_content, where
SENAME is the hostname of the Service Engine.
Note The redirected URL for Flash Media Streaming requests is
rtmp://SENAME.SE.RFQDN/application_name/encoded (relative_path_of_streamname), where
SENAME is the hostname of the Service Engine.
When IP-based redirection is enabled, the Service Router uses the IP address of the Service Engine in
the URL instead of the hostname. The redirected URL is http://<se ip addr>/ipfwd/<rfqdn>/<path>. The
IP-based redirection method avoids the extra DNS lookup that was required in the RFQDN redirection.