view of what Portal support does:

https://users.emulab.net/trac/emulab/wiki/Portal

Notes:

* New DB tables to store the list of peer emulabs, and exports info
  for users and projects.

* Backend script to manage user and projects exports.

* Cross site login from the portal; users do not login into the peer
  sites directly.

* New portal_daemon to run on the portal, to handle exports and
  updates.