Redirect virtual server to complete url

You wouldn't want to redirect to www.abc.com:7777, because that would cause the browser to try to open the connection on port 7777, and your VIP is only listening on port 80. At most you'd want to add the port to the Host header on its way through the proxy, but that's rarely necessary. The pool itself should be defined with the services listening on port 7777.

when HTTP_REQUEST {
    if { [HTTP::uri] equals "/" } {
        HTTP::redirect "http://[HTTP::host]/blah/blah/blah"
    } else {
        HTTP::header replace Host "www.abc.com:7777"
    }
}

If the URI is empty (/), then redirect to /blah/blah/blah. Otherwise replace the incoming Host header (as required).