Specifications

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Cisco Internet Streamer CDS 2.0-2.3 Software Configuration Guide
OL-13493-04
Chapter 4 Configuring Devices
Configuring the Service Engine
Execution Order of Rule Actions
The order in which the rule actions are executed is as follows:
1. block or allow
Note The allow and block actions carry the same precedence. The order of execution depends on
the order of configuration between allow and block actions. Other actions always take
precedence over allow.
2. redirect (before cache lookup)
3. rewrite (before cache lookup)
4. refresh (after cache lookup, in the case of cache hit)
5. no-cache
6. use-icap-service
7. generate-url-signature
8. validate-url-signature
9. allow
Note When configuring service rules, you must configure the same service rules on all SEs participating in a
delivery service in order for the service rules to be fully implemented. The rule action must be common
for all client requests because the SR may redirect a client request to any SE in a delivery service
depending on threshold conditions.
Configuring ICAP
The Internet Content Adaptation Protocol (ICAP) is an open-standards protocol that can be used for
content adaptation. Content adaptation includes content translation, content filtering, and content
insertion. ICAP specifies how the SE, acting as an HTTP proxy server, can communicate with an external
server, which filters and adapts the requested content. This allows you to set up interoperability with
Camiant PCMM-compliant third-party policy servers to allocate guaranteed bandwidth for authorized
requests of content.
ICAP provides two content-processing modes for HTTP services. These modes define the transactions
that can occur between an SE acting as an ICAP client and the external ICAP server. The two modes are
as follows:
• Request modification (reqmod)—Allows modification of requests as they are sent from the SE to
the ICAP server on their way to the origin server. The ICAP server can modify these requests
depending on the content requested.
• Response modification (respmod)—Allows modification of requests after they return from the
origin server. The ICAP server only acts on requested objects only after they return from the
origin server.
An ICAP service is a collection of attributes that define the service and one or more ICAP servers that
provide the ICAP services. You can configure a maximum of ten ICAP services per Content Engine, with
an upper limit of five ICAP servers per ICAP service. Also, you can choose to apply ICAP services on
all HTTP requests processed by the Content Engine or apply ICAP processing only to requests that
match the Rules Template.