redirect iRule to different uri

This will do what you are asking:

when HTTP_REQUEST {
  if { ([HTTP::host] eq "sapxpq.browning.k12.ia.us") and [HTTP::uri] < 2 } {
    HTTP::redirect "http://sapxpq.browning.k12.ia.us:50100/irj/portal"
  }
}

However, is this really what you want? You will need a virtual listening on port 50100 as well, or the virtual setup originally will have to listen on port 0 so that port 80 and port 50100 can be accomodated.

The LTM will do the port redirection for you, so if that is your concern, you could just redirect them to http://sapxpq.browning.k12.ia.us/irj/portal and the requests will look like this:

Hitting LTM:

http://sapxpq.browning.k12.ia.us:80/irj/portal

Hitting Server:

http://server_IP:50100/irj/portal

HTH....Jason