The E-LAN needs to be able to talk to the Primary and Secondary UCM servers.
If these elements are part of the same subnet, then you don't need explicit routing.
I currently have several release 6 sites. My Primary UCM is at my HQ location, and the Secondary UCM is at our Disaster Recovery site. The 3rd octet of the IP address for each site is different, and all of the E-LANs are routable so that they can talk to the Primary and Secondary UCMs, and also so that I can reach them via our Corporate Network instead of relying on modem access.