on the 'A Protocol for Packet Network Intercommunication'

It was 37 years ago when Turing awardees Vinton Cerf and Robert E. Khan published the seminal paper describing TCP (with implicit mention of IP) which eventually led to the development of the Internet.

The paper proposed a protocol which would allow internetwork communications between processes on hosts residing in different packet switching networks. The paper stated the issue of how would such protocol handles communications between existing and planned packet switching network infrastructure, which would likely be different from one another. So it was here that the idea of having a standard protocol, which is as simple and reliable as possible, for inter process and network communications came in. Since reliability is one of the top concerns of the protocol, a mechanism for detection of ‘lost’ packets and their retransmissions was also included. A sender TCP will wait first for the receiver TCP to acknowledge bytes of messages it previously sent. If it does not receive such acknowledgment within a defined timeout, it re-transmits the unacknowledged bytes. State information of the connection between two communicating processes are kept only at both ends of the communication link, thus making the tasks of intermediary points as simple as possible i.e. only handles forwarding of packets and fragmentation if needed. Provisions for flow control was also included which is based on a window strategy. With this flow control mechanism, the receiver TCP will be able to advertise the number of bytes of data (the window) it can handle to the sender TCP, hence controlling the amount of data that flows between the receiver and sender TCP. One should really appreciate the completeness of the mechanisms or features of the protocol suggested in this paper, considering that most of them were given entirely in their pure theoretical sense. Amazing!