2000 hosts: small potatoes. Allow me to rephrase my question: if you put locators in the border router and they are unknown to the hosts, why would it be harder? You would not have to communicate policy to the hosts.
How does this differ from the GSE proposal -- routing goop inserted at the edge routers? Would these locators be considered part of the IP address by upper layers? What happens when a communication that was within the site (no locators present) starts bouncing off of an edge router, due to dynamic routing changes? If a host needs to send its identifier and locator information to another host (as in the FTP PORT command), what does it send? Margaret