Https Redirection Irule

try this ltm policy ( min version 11.4) and attach it to the VS:

ltm policy pol_btoperator {
    controls { forwarding }
    requires { http }
    rules {
        root_redirect {
            conditions {
                0 {
                    http-uri
                    path
                    values { / }
                }
            }
            actions {
                0 {
                    http-reply
                    redirect
                    location /sm/index.do
                }
            }
            ordinal 2
        }
    }
    strategy first-match
}