CS268 Reading Review

Scalable support for transparent mobile host internetworking

David B. Johnson
Review by Feng Zhou
2/10/2003

The problem: Designing a facility on top of existing IP infrastructure to support transparent mobility of IP. The design should be scalable, efficient, incremently deployable and compatible with existing IP.

Key points:

  1. Mobile IP involves the modification to IP software on both mobile and correspondent end-hosts, the addition of a home agent and an optional remote agent. Packet tunneling is used to deliver packets to the mobile host. Basic mobile IP uses triangle routing to deliver every packet, which has poor performance. Routing optimization, on the other hand, caches the care-of address of mobile hosts at the correspondent end-host or its local router, which in turn tunnels the packet directly to the mobile host without doing triangle routing.
  2. The point that home agent is the authority of all location information is important. This ensures that the system can operate reliably and robustly. Proper authentication is needed to prevent malicious parties from hijacking the mobile host, the home agent or the remote agent.
  3. Security is a weak point of the mobile IP design presented in this paper. The biggest problem is, in order to use the routing optimization, the home agent of mobile hosts and all remote hosts must maintain pair-wise shared secret. Although the pairs can be established on an organization basis, thus reducing the number of different keys, this will still be a large deployment obstacle. Keeping the shared-key secret will also be a hard task, because a large number of remote hosts in the same organization all know the secret key. Thus preventing the disclosure of the key poses a considerable administrative overhead.