Nautilus6 - Multihoming Activity

Multihoming refers to a situation where a node can choose between several paths to reach a correspondent, either because the node has several interfaces to choose from, or because the network where it is located in is connected to the Internet by several routers, or by routers with several interfaces. Such a configuration is particularly useful in mobility contexts because it ensures mobile entities remain permanently connected to the Internet upon loss of connectivity (as a result of moving out of a coverage area or because wireless technologies are more subject to interferences), lack of connectivity (a given technology cannot cover all geographic areas) or lack of bandwidth (technologies with high bandwidth are generally not available for mobile users). Besides enhanced session continuity, it also allow to choose and balance the traffic between the available connections.

The question of mobile hosts with multiple interfaces has been discussed at the IETF in the Mobile IP working group. Many solutions have been proposed, but none has ever been adopted as a working group solution. As a matter of fact, the working group doesn't have much interest in including this topic in its deliverables, although several people have pushed for it. What is indeed missing is a comprehensive problem statement. Meanwhile, the NEMO working group has been entertaining discussion turning about multihomed mobile networks since almost the first day it was setup. We are leading and actively contributing to this discussion since the beginning.

The objective of our investigation of multihoming in mobile environments (mobile hosts and routers with multiple interfaces; and mobile networks with multiple mobile routers) is to push forward the standardization process at the IETF (many solutions exists, but they do not share a common understanding of the problem) by understanding and defining the problem for host mobility and network mobility. We also intend to demonstrate the benefit of multihoming for mobile hosts and networks; for doing so we need to implement protocols and design demonstrative applications.

During the course of this year, our in-depth investigation of this issue resulted into a few internet drafts submitted to both the NEMO and Mobile IP working groups in parallel to conference papers. We carried on standardization activities at the IETF for both multihomed mobile hosts and multihomed mobile networks. We also carried out some testing on our in-door testbed, we developed protocols and performance evaluation tools, and we conducted more academic research activities.

Some solutions to deal with multihoming issues in mobile environments (such as Multiple Care-of Addresses registration) are already implemented on Mobile IPv6 and NEMO Basic Support implementations. Check the implementation page.