NFD

20140223 conference call reviewed NDN hub discovery procedure revision 1.

• Three steps have different purposes:
  1. If there is a HUB in one-hop, use that HUB.
  2. If IP network announces a NDN hub using DNS search domain, use that HUB.
  3. If IP network does not announce a NDN hub using DNS search domain, connect to the home HUB.
• UDP multicast face is created when NFD starts, and can be used for communication. However, step 1 is still needed:
  • You don't know whether you can reach broader NDN network by UDP multicast.
  • Multicast has overhead.
• Data packet in reply to step 1 Interest should be signed by the site key, which in turn is signed by NDN testbed root key.

fake route to /autoconf is actually a tag that indicates a face is created by autoconf tool.
The alternates to using a fake route are:

• Store in a file.
• Store in a Data packet written to a repository.
• Set a string description on the Face in an argument to FaceMgmt create command.
• Store in a variable in NFD, and define a new command in FaceMgmt to access this variable.

The reason to have this tag is: the face to old HUB should be deleted when autoconf tool executes again and finds a different HUB, after network environment changes.

Deleting the face to old HUB is not always necessary, because:

• If the old HUB becomes inaccessible, the face would be created due to UDP send error.
• If the old HUB is reachable but slow, strategy should favor the new HUB.

The fundamental questions are:

• How many HUBs can a laptop simutaneously connect to?
• How long should a laptop keep faces to old HUBs?
• How many faces to old HUB should a laptop keep?

We decide not to have this tag in first release, because there aren't many HUBs at this time.

The questions should be revisited after first release.