User manual

1
Chapter 1
Introduction
The Cobalt CacheRaQ 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 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 can operate in several modes:
•
Traditional Proxy Caching mode . Client Web browsers are
configured explicitly to request documents from the
CacheRaQ. The browsers can be configured to do this by
either individual users or a central manager of browser
configuration files. The CacheRaQ 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. The CacheRaQ
detects users’ requests for Web documents (HTTP requests),
which are then handled by the CacheRaQ’s software. No
browser configuration is necessary.
• Clustering . Several CacheRaQs are configured in a cluster.
Clustering can be done in either Traditional Proxy Caching
Mode or Transparent Caching mode. In a Cluster
configuration, the Cluster Master receives clients' HTTP
requests 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.