Hi Dhananjay,
I don't think LTM enforces any limit on the length of a URI. This page (WWW FAQs: What is the maximum length of a URL?
Click here) summarises common browser URL limits.
When you say the load balancer breaks the connection, do you mean LTM sends TCP resets to the client and/or server? Do you see any errors in /var/log/ltm? Else, what are the symptoms of the issue? Do you see the request received by LTM and not sent to the server? Does the server receive the request but log an error? Also, which LTM version are you running?
Thanks,
Aaron