Csep-561-Reading-1A

The design philosophy of the DARPA internet protocols

The core features of the Internet came about due to the priorities of the military, oddly enough. Certain aspects of these priorities, such as favoring robustness of communications over cost efficiency & resource accounting, have resulted in systems that are arguably not ideal for the Internet of today, which is more of a ubiquitous shared resource across all of society than was likely imagined by DARPA in the 1970s.

Datagram

The use of the datagram as the entity which is transported across underlying networks is the defining feature of the Internet. It has:

1. enabled stateless connection between switching nodes
2. provided a basic building block, out of which varying types of services can be implemented
3. enabled a variety of networks to be realized in the Internet, since it is ultimately a small, minimum network service assumption.

TCP

TCP went through many revisions. Initially the protocol supported "flow control" based on both bytes and packets. But this was too complex in practice, so it shifted to byte only (for a variety of reasons). Now, TCP doesn't rely on packetization at all.