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The Cobalt CacheRaQ 4 is a dedicated World Wide Web caching device — it
stores documents that have been retrieved from the Web. Once a document has
been retrieved from the Web, users can obtain it from the CacheRaQ 4 without
having to access the Web again. This reduces the communication load on the
Wide Area Network (WAN) and helps users obtain Web documents much more
quickly.
The Cobalt CacheRaQ 4 can operate in several modes:
•
Traditional Proxy Caching mode. Client Web browsers are configured
explicitly to request documents from the CacheRaQ 4. Either individual
users or a central manager of the browser configuration files can configure
the browser to do this. The CacheRaQ 4 also supports the use of a proxy
auto-configuration (PAC) file for browser configuration.
•
Transparent Caching mode. All client network traffic is automatically
routed through the CacheRaQ 4. The CacheRaQ 4 detects users' requests for
Web documents (HTTP requests), which are then handled by the
CacheRaQ 4's software. No browser configuration is necessary.
•
Clustering. Several CacheRaQ 4s are configured in a cluster. Depending on
the method of clustering used, clustering can be established in either
Traditional Proxy Caching mode or Transparent Caching mode. The
CacheRaQ 4 supports a variety of clustering methods: InstaCache (based on
Cache Array Routing Protocol [CARP]), Inter-Cache Communication
Protocol (ICP) and Web Cache Communication Protocol (WCCP). WCCP
works in Transparent Caching mode only.
In a Cluster configuration, the Cluster Master receives HTTP requests from
the client by either of the two methods described above. Each request is
forwarded dynamically to one of several Cluster Slaves. The Cluster Slave
retrieves the document, either from its cache or from the document's original
server. The Cluster Slave returns the document to the Cluster Master, which
forwards it on to the requestor. Because the work of managing cached
documents is divided evenly among Cluster Slaves, clustering allows for a
greater volume of HTTP traffic.
Cobalt CacheRaQ 4 User Manual
Introduction
Chapter 1
1
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