Cisco ASR 5000 Series, Обзор продукта

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Content Filtering Support Overview
Category-based Content Filtering Support ▀
Cisco ASR 5000 Series Product Overview ▄
OL-22938-02
Static Rating Categorization Database (SRDB)
This is an internal categorization database (periodically synchronized with an external server) that provides ratings for
publicly accessible traditional and mobile Web sites. When the SessMgr passes a URL/URI to internal list server, the
list server returns a list of matching category ratings.
The list server is used to determine whether a Web site has already been classified. When the list server passes back a
category rating to the filtering application, the rating is compared against the Category Policy ID applied for the
subscriber to determine the appropriate action like accept, block, redirect, or replace. If the list server returns a clean
rating, there is no need to perform a real-time analysis of any content delivered by the site.
When a blocked or rejected content rating is returned, the SessMgr can insert data such as a redirect server address into
the bearer data stream. If no rating is returned this means the site is capable of returning either clean or unacceptable
content.
Each SRDB contains a replication object consisting of hash tables that map known Web sites and their subdirectories to
their respective category ratings. The SessCtrl reads the index of SRDB tables with a data structure that associates keys
with URL rating values and loads it onto the SRDB managers.
To boost performance and provide high availability, SRDB Manager provides functionality to load the Optimized
Content Rating Master Database (OPTCMDB) volumes from its peer SRDB task. If the peer SRDB task is not in
loading state then the OPTCMDB loading is done through SessCtrl to the recovered SRDB task.
Rater Package Model Files
The real-time analyzer requires a model file that defines the features which are necessary to classify a Web page as
belonging to a specific category and language. A model file per category is created by analyzing the traits of thousands
of pages of that category and thousands of pages that does not belong to that category. For some categories, a feature
counter file is used to decide whether or not to evaluate the Web page against the respective model file.
When URL Blacklisting solution is the only content filtering enabled on a system, no SRDB tasks are spawned at
startup. Only when either Category-based Content Filtering is enabled in isolation, or with URL Blacklisting, the SRDB
tasks are spawned.
Content Rating Rules Update Server
This is a third-party content rating solution for exporting content filtering rules database information to the Category-
based Content Filtering system. In addition, while exporting database updates, it collects reports of URLs processed by
ECS and Content Filtering services that are reported as unknown in the deployed static rating database. This server
analyzes these URLs and provides the rating in future updates for static rating database.
This server provides the following support to Master Content Rating Database Server (MCRDBS) for the content rating
function:
Provides full Vendor Format Master Database files (VFMDB) to MCRDB server on request from MCRDBS.
Provides incremental Vendor Format Master Static URL Database file (VFMDB-INC) to MCRDBS when any
incremented VFMDB is available and requested from MCRDBS.