It sounds like you're not looking for a redirect, though. My definition for a redirect is to send a directive to the client to make a new request (e.g. 301, 302, 307). If you're not telling the client to make a new request you're directing ('routing'), not redirecting. Perhaps this difference is a bit artificial, but it does help to keep the requirements clear.
Either way, I think "HTTP::uri" is what you're looking for. It changes the URL is passed from the LTM to the node. Details: https://devcentral.f5.com/wiki/irules.http__uri.ashx
Nimbostratus
