The paper presented a protocol that supports sharing of resources among different packet switching networks as well as mechanisms to handle some issues that may arise in implementing the said protocol.
A packet switching network is composed of HOSTS, set of packet switches and a collection of communication media that interconnect the packet switches. This paper elaborated on how communication between hosts in different networks happen as well as how data is routed from one network to another.
There were two main concepts discussed in this paper that played a major role on how the protocol resolve the issues that arise in interconnecting existing networks.
To overcome the difference in implementation of existing networks without imposing a uniform practice, the concept of Gateway was introduced. It is an interface that is responsible for passing data between networks. It may split a large packet into two or more packets but it is not responsible for reassembling. The gateway sees to it that these packets meet the requirements of its target network.
The next one was Transmission control program (TCP). Processes that want to communicate present messages to TCP for transmission. TCP delivers these messages as packet through the network. As these packets may propagate through the packet switches, the TCP on the receiving end is responsible for the reconstruction of these packets and delivery of the original message to its destination process. Each packet have assigned sequence number to determine the relative location of the packet text in the messages under reconstruction. This solves the out of order arrival of packets. End of segment (ES) and End of message (EM) flags are used by the destination TCP to discover the presence of check sum for a given segment and to discover if the message has completely arrived. The source TCP waits for acknowledgement from the destination TCP to see if retransmission of the packet is needed. A window strategy is also used in order to aid in duplicate detection.
With these mechanisms, issues like individual network packet sizes, transmission failures, sequencing, flow and error control and so on can be addressed. They have described a good protocol in transmitting data between existing networks. The design focused heavily on reliability so it might not be suitable for types of service that require fast communication between two hosts.
Reference:
Vinton G. Cerf and Robert E. Kahn, A Protocol for Packet Network Intercommunication, 1974
Reference:
Vinton G. Cerf and Robert E. Kahn, A Protocol for Packet Network Intercommunication, 1974
your summary is concise, though i would like to know your critique of the paper, maybe some insights and comments about it, etc.
ReplyDeleteSuch a comprehensive summary as it thoroughly touched on the main points of the paper. :) But same with the fellow commenter above, would also love to hear your critique on it (insights, thoughts, recommendation, etc) :)
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