Adding Catchall Behavior to iRule

I think the issue is with your

*

switch -glob -- [string tolower [HTTP::uri]] {
    "/shortname1*" {
         Do nothing
    }
    "/blah/shortname*" {
        HTTP::uri "/ShortName1"
        pool CUSTOM_POOL2
    }
    default {
        HTTP::redirect "/ShortName1"
         If you perform the redirect there's no reason to set the pool, because the client will redirect.
    }
}

Of course, you can make changes like if you need to maintain the original URI after the /shortname or if you want to add more options.

Hope this helps