Delay-Tolerant Network Architecture for Challenged Internets

"Challenged Internets" are a class of network that have characteristics such as long delays, low reliability, and periodic disconnection that make the IP protocol an infeasible way to interconnect such networks; each network uses ad-hoc protocols that do not necessarily provide the baseline best-effort packetized service required by IP. Furthermore, TCP and similar protocols require end-to-end connectivity, which may rarely happen in these challenged networks. Internetworking them, in the vision of the paper, requires a new set of underlying protocols similar in spirit to IP but one that takes into account the differing requirements of these networks.

The argument in the paper is that using PEPs or middleboxes to make these challenged networks appear as "normal" IP networks is insufficient and only really works if the challenged networks are on the edges. I agree with the latter part of the argument; it doesn't seem very easy to connect two different such networks through IP middleboxes in the middle of an internet.

Basically, the new internetworking protocol for challenged networks needs to provide several classes of service that are unlike IP services. In the paper they use USPS as a basic point of departure for the kinds of service these networks require, and propose to have the same basic set of services. To me, the difference between these networks and the internet is that intermediate nodes must have more than just transient state in the connection; it really is a hop-to-hop connection where at each point, the endpoints OF THE HOP have all the state.

One interesting thing is how they propose to handle naming. In this approach, there is a global set of names that are world-resolvable, and within each set, a locally-resolvable name is used. Thus a tuple represents "route to this network" followed by the address of the resource as a locally-resolvable name in the network. This is probably doable given the limited size (in number of networks) such an internet would have.