From: Ethan Phelps-Goodman (ethanpg@cs.washington.edu)
Date: Tue Oct 05 2004 - 22:04:37 PDT
A Protocol for Packet Network Intercommunication
Cerf and Kahn
Cerf and Kahn present a high level specification of the TCP/IP
protocol. The protocols are specifically aimed at linking existing
heterogeneous networks. They enumerate potential hurdles for connecting
disparate networks: varying addressing schemes, packet size and delay;
reconstructing lost data; and monitoring network state. As mentioned in
the previous paper, the last goal is largely unmet.
Networks are linked by a gateway that sits on two different networks at
once. This seems to be a new contribution of this paper. The IP layer
requires very little of the underlying networks. The underlying
networks may use any packet size, routing scheme, and header
information. IP is responsible for specifying a global network
identifier, but the individual network decides how to interpret the
host field, and the individual host decides how to interpret the port
number. A lot of attention is paid to sequencing and reconstruction,
retransmission, and managing connections (a term which they somewhat
dislike.) A key strength in all of this is that the fundamental design
is made explicit, but many low level details are left up to the
implementation. This was probably appropriate since the protocol was
still in its early stages.
Although there are justifications for some of the design decisions,
there is no attempt made to asses the workability of the protocols. The
paper very much needs a followup study to assessing the performance of
a prototype.
Ethan
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