Specifications

1-21
Cisco Internet Streamer CDS 2.0-2.3 Software Configuration Guide
OL-13493-04
Chapter 1 Product Overview
Content Delivery System Architecture
Service Router Workflow
The Service Router workflow for clients connected to the service provider’s network is as follows:
1. The client sends the DNS query for the routed FQDN to the local DNS server.
2. The DNS server replies with the Service Router IP address.
3. The client issues an HTTP or RTSP request to the Service Router.
4. If the Service Router finds the client’s subnet in the Coverage Zone file, the following occurs:
a. The Service Router chooses the appropriate Service Engine and performs a protocol-specific
redirection.
b. The client issues an HTTP or RTSP request to the Service Engine.
c. The Service Engine serves the content.
If the Service Router does not find the client’s subnet in the Coverage Zone file and location-based
routing has been enabled, the following occurs:
a. The Service Router communicates with a Geo-Location server and gets the geographical
coordinates of the client’s IP address.
b. The distance is calculated between the client and the Service Engines, and the Service Engine
closest to the client is selected.
c. The Service Router performs a protocol-specific redirection with the closest Service Engine.
d. The client issues an HTTP or RTSP request to the Service Engine.
e. The Service Engine serves the content.
When a Service Router is registered with the Internet Streaming CDSM, the CDSM propagates the
Service Router’s IP address to all the registered devices. The Service Engine sends a keep-alive message
to the Service Router on a periodic interval, which consists of information about the disk health, whether
the Internet Streamer application is enabled or not, and the load of the Internet Streamer application on
the Service Engine. The Service Router uses the Service Engine’s load and liveness information for
generating the routes.
The Internet Streamer CDS can have more than one Service Router in order to support Service Router
failover. In line with failover, the DNS server should be configured with multiple Service Routers for the
same routed FQDN.
Note DNS entries for all FQDNs must be delegated to the Service Router. In the DNS server’s database file,
a name server record must be entered for each FQDN that routes to the Service Router.
Coverage Zone File
When a Service Engine is registered to the Internet Streaming CDSM, it is assigned a default Coverage
Zone file that is created by the CDSM using the interface IP address of the Service Engine. The default
Coverage Zone file can be unassigned, and a custom coverage zone can be created using the Coverage
Zone file.
A Coverage Zone file is an XML file containing coverage zone entries for each client IP address range,
the Service Engine serving that range, the latitude and longitude of the Service Engine, and a metric
value. The Coverage Zone file can be referenced by a URL and imported into the Internet Streaming
CDSM, or uploaded from a local machine. The Coverage Zone file can be set as the default for a specific
Service Router or for all Service Routers in the CDS network.