A Delay Tolerant Network Architecture for Challenged Internets

This paper addresses address the issues of links from the network with extra long delay and also unreliable connectivity and poor operation characteristics. The paper calls these kind of networks challenged networks. The paper states that the current internet makes certain assumptions about the underlying architecture and it's basic reliability and performance. I think this is only true in some cases. The basic internet architecture itself i don't think makes that assumption, that's why this research is even possible. From what i got from the paper, the mail idea is to insert nodes (they call it DTN Gateways) into the network to split the network into different Regions. Then within the Regions define the network characteristic of the region. The DTN nodes are therefore responsible for the retransmission and reliable transfers. The rest of the paper describes the different routing and naming algorithms of this overlay network. This reminds me of the split TCP mechanism, where in the middle of the TCP connection you have a midway point that is also responsible for a similar mechanism.

The idea presented isn't completely new, but in the original internet architecture proposal, one of the main points was not to keep state in the network. However, now with more and more wide range use of the network, it seems like there are several benefits of keep state in some nodes of the network. It seems like with challenged networks, such unreliability requires some sort of retransmission unit. But another argument is: that's what the different layers are for, thus we can implement it in the link layer or have a stronger retransmission mechanism. Nonetheless, with the internet evolving and more and more networks wanting to integrate into the internet, it seems like states in the network are somehow unavoidable.