Nortel Web OS 10.0, Application Manual

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Web OS 10.0 Application Guide
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Chapter 15: Content Intelligent Switching
212777-A, February 2002
HTTP Header Inspection
Content intelligent switching is performed by inspecting HTTP headers. HTTP headers
include additional information about requests and responses. The HTTP 1.1 specification
defines a total of 46 headers. For Web Cache Redirection, at any given time one HTTP header
is supported globally for the entire switch.
HTTP headers can be general, request, response, or entity headers. General headers may exist
in both requests and responses. Requests and response headers are specific only to requests and
responses, respectively. Entity headers describe the content of the request body or the content
of the response body.
Each HTTP header field consists of a name, followed immediately by a colon ( : ), a single
space character, and the field value. Field names are case-insensitive. Header fields can be
extended over multiple lines by preceding each extra line with at least one space.
Some customer applications of HTTP header inspection are listed below:
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Redirection based on domain name
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Cachability based on domain name
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Virtual hosting
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Redirection based on browser type
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Cookie-based preferential redirection
Buffering Content with Multiple Frames
To handle the overall length of HTTP headers, including request headers containing multiple
cookies, and the Maximum Segment Size (MSS) of dial-up connections, Web OS software
provides the following support:
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HTTP GET Request Headers
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– In addition to the URL path, which generally is less than 300 bytes, the HTTP GET
requests also include general headers and request headers.
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Parsing GET requests to match URL path and HTTP header beyond the first frame
while performing delayed binding
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Processing multiple frames from a single HTTP GET request, using a TCP stack on
the switch
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HTTP Cookie Request Headers
Buffering a maximum of 4500 bytes for a single GET request across multiple frames. A
single GET request can include multiple cookies.