Redirect to another Pool

your code is not too complete as it starts with 'elseif'.. so not clear.

elseif { ($requestURI starts_with "/rd/")} { 
   HTTP::respond 302 location "https://www.abc.com/"; 
   TCP::close
} elseif {($requestURI equals "/")} { 
   pool ext_B pool 
}

You seem to be doing two things: First redirecting path starting with /rd/ to the root path, and then second allocating the resource depending on the path.

Is it that you want anything starting with /rd/ to go to poolB and that it should also all be on the root path of poolB? ANything else goes to poolA? I would do that without any redirect..

if { $requestURI starts_with "/rd/" } {
   HTTP::path "/"
   pool poolB
}

Make the virtual server default pool poolA. So everything would go to poolA unless the path starts with /rd/. In that case it would use poolB and replace the path with the root path on that pool of servers.