An End-to-End Approach to Host Mobility

Motivation: The paper proposes a design of an end-to-end architecture for
Internet host mobility using dynamic updates to the DNS to track host
location and provides a pure end system alternative to routing based
approaches such as Mobile IP.

Key Points:

1) According to the end to end argument, functionality is often best
implemented at a higher layer at an end system where it can be done
according to the application's specific requirements.This paper provides
mobility as an end-to-end service without network layer support while
providing multiple mobility nodes.

2) When a host changes its network attachment point (IP address) to sends a
secure DNS update to one of the name servers in its home domain updating its
current location. Further, the DNS mappings for these hosts are uncacheable
by other domains so stale bindings are eliminated.

3) The TCP connection migration is done through the Migrate TCP option
included in SYN segments that identifies a SYN packet as part of a
previously established connection rather than a request for a new
connection. After a successful token negotiation in Migrate-Permitted
option, TCP connections are uniquely identified by <source address, source
port, token>.

4) To prevent TCP connections from being hijacked, hosts wishing to
cryptographically secure the connection token may conduct an Elliptic Curve
Diffie-Hellman key exchange through the option negotiation. IPSec provides a
way of securing TCP migration however IPSec has not found wide spread
deployment as yet.

5) The Migrate_Wait state prevents connections form being inadvertently
dropped if the address allocation policy on the mobile host's previous
network reassigns the mobile host's old IP address before the mobile host
reconnected at a new location and had a chance to migrate the connection. It
also prevents the continued retransmission of data to an unreachable host.

6) However, both peers cannot move simultaneously. Their target is mostly
infrastructure based rather than ad-hoc netowrk topologies.Also, the system
requires changes to each transport protocol because of the implementation of
migration at end points.

7) It also leads problems in applications which make assumptions about the
stability of network addresses which are no longer valid in the proposed
architecture.

8) When a mobile host accepts no passive connections, the protocol does not
require even the DNS update notification and seamless connectivity across
host mobility is achieved.
Received on Thu Oct 19 2006 - 10:22:34 EDT