Cache-control

Some BAckground (taken from wikipedia) :-

HTTP header fields are components of the message header of requests and responses in the Hypertext Transfer Protocol (HTTP). They define the operating parameters of an HTTP transaction. Cache-control is one of the HTTP header fields. And as F5 is taking care of the redirection , we need to take this field into account with IE 10 roll out.

General Format :-  The header fields are transmitted after the request or response line, which is the first line of a message. Header fields are colon-separated name-value pairs in clear-text string format, terminated by a carriage return (CR) and line feed (LF) character sequence. The end of the header fields is indicated by an empty field, resulting in the transmission of two consecutive CR-LF pairs. Long lines can be folded into multiple lines; continuation lines are indicated by the presence of a space (SP) or horizontal tab (HT) as the first character on the next line.

For more details :- Please visit.  http://en.wikipedia.org/wiki/List_of_HTTP_header_fields

 

Problem Description:-

With rollout of IE 10 to our project workstations we encounter a problem with redirection performed on F5 LTM. After opening website on one window when we open another tab , and type same website address Browser freezes and no redirection occurs.

Solution:-

After lots of investigation , talking to F5 and Microsoft experts , we finally agreed on the solution that to prevent this we need to add cache-control HTTP header to the redirection response with value “no-cache”.

Current Irule:

when HTTP_REQUEST {
switch -glob [string tolower [HTTP::host]] {
“afrozahmad.com” {
HTTP::respond 301 “Location” “http://www.afrozahmad.com/en/Pages”
}
}
}

Modified Irule:- We have added  { cache-control “no-cache” } .

when HTTP_REQUEST {
switch -glob [string tolower [HTTP::host]] {
“afrozahmad.com” {
HTTP::respond 301 “Location” “http://www.afrozahmad.com/en/Pages” Cache-Control “no-cache”
}
}
}

 

Useful Sites for more information:-

http://support.f5.com/kb/en-us/solutions/public/13000/200/sol13244.html?sr=38385738 > Overview of RAM cache

http://support.f5.com/kb/en-us/solutions/public/10000/200/sol10200.html?sr=38385738 > Clearing ram cache entries

http://www.mobify.com/blog/beginners-guide-to-http-cache-headers/  > A Beginner Guide to HTTP Cache headers

http://condor.depaul.edu/dmumaugh/readings/handouts/SE435/HTTP/node24.html  >