ECS supports the
streamlined ICAP interface to leverage Deep Packet Inspection to enable
external application servers to provide their services without performing DPI,
and without being inserted in the data flow. For example, with an external
Active Content Filtering (ACF) platform.
A high-level view of
the streamlined ICAP interface support for external ACF is shown in the
Figure 4. High-Level View of Streamlined ICAP Interface with External
The system with ECS is
configured to support DPI and the system uses this capability for content
charging as well. WAP and HTTP traffic is content filtered over the ICAP
interface. RTSP traffic that contains adult content can also be content
filtered on the ICAP interface. Only RTSP Request packets will be considered
for content filtering over the ICAP interface.
If a subscriber
initiates a WAP (WAP1.x or WAP2.0) or Web session, the subsequent GET/POST
request is detected by the DPI function. The URL of the GET/POST request is
extracted and passed, along with subscriber identification information and the
subscriber request, in an ICAP message to the application server.
In the case of
Category-based Content Filtering solution, the application server checks the
URL on the basis of its category and other classifications like type, access
level and content category and decides if the request should be authorized,
blocked, or redirected by answering to the GET/POST with:
A 200 OK message
if the request is accepted.
A 302 Redirect
message in case of redirection. This redirect message includes the URL to which
the subscriber should be redirected.
A 403 Denied
message is the request should be blocked.
Depending on the
response received, the system with ECS will either pass the request unmodified,
or discard the message, and respond to the subscriber with the appropriate
redirection or block message.
Content Charging is
performed by the ECS only after the request has been controlled by the
application server. This guarantees the appropriate interworking between the
external application and content-based billing. In particular, this guarantees
that charging will be applied to the appropriate request in case of
redirection, and that potential charging based redirections (i.e. Advice of
Charge, Top Up page, etc.) will not interfere with the decisions taken by the
The ACF performs the
subscriber policies based on the subscriber identity passed in the ICAP
appropriate action (permit, deny, redirect) to take for this type of content
based on subscriber profile.
the action (permit, deny, or redirect) decision for the URL back to the ECS
For information on
configuring the ICAP interface functionality for external ACF servers, see the
Support chapter of the