Connected: An Internet Encyclopedia
The Problem
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The Problem
The Problem
The world is a jungle in general, and the networking game
contributes many animals. At nearly every layer of a network
architecture there are several potential protocols that could be
used. For example, at a high level, there is TELNET and SUPDUP
for remote login. Somewhere below that there is a reliable byte
stream protocol, which might be CHAOS protocol, DOD TCP, Xerox
BSP or DECnet. Even closer to the hardware is the logical
transport layer, which might be CHAOS, DOD Internet, Xerox PUP,
or DECnet. The 10Mbit Ethernet allows all of these protocols
(and more) to coexist on a single cable by means of a type field
in the Ethernet packet header. However, the 10Mbit Ethernet
requires 48.bit addresses on the physical cable, yet most
protocol addresses are not 48.bits long, nor do they necessarily
have any relationship to the 48.bit Ethernet address of the
hardware. For example, CHAOS addresses are 16.bits, DOD Internet
addresses are 32.bits, and Xerox PUP addresses are 8.bits. A
protocol is needed to dynamically distribute the correspondences
between a pair and a 48.bit Ethernet address.
Next: Motivation
Connected: An Internet Encyclopedia
The Problem