URI prefix iRule

So if I understand you correctly, if the URI does not begin with /sites/web you want the user redirected to www.common.com/sites/web with the original URI appended. Something like this:

when HTTP_REQUEST {
    if { ! ( string tolower [HTTP::uri] starts_with "/sites/web" } {
        HTTP::redirect "www.common.com/sites/web[HTTP::uri]"
    }
}

If the URI sent from the client is / the user will be redirected to www.common.com/sites/web/. If the URI sent from the client is /table the redirect will be www.common.com/sites/web/table, or if the original URI is /abc/1234 the redirect will be www.common.com/sites/web/abc/1234.

Does that sound like what you want?

Robert