GM anticipated robots and
other automated equipment attached to the network, and predictability of response to a problem was
very important. MAP was a token-passing protocol that provided relatively uniform access time to
each device on the network. In contrast, Ethernet??™s CSMA/CD protocol could not guarantee any
worst case access time to the network, because the frequency of collisions and retries on the network
depended on the loading of the network.
GM also liked the broadband, cable TV wiring specification of MAP. With broadband, the wiring
could handle many channels at once, allowing for networking, video, and other communications over
common cable. The broadband wiring also provided greater immunity to electrical noise, such as
that from welders and other equipment in the factory.
Ethernet, or 802.3, was more successful with most customers, partly because it had a head start.
Also, the imagined problems of responsiveness with Ethernet generally did not occur in practice.
In addition, the wiring was less expensive and less complicated.
7.8 The HTTP protocol is essentially a protocol providing for file transfer between the server and the client.
Therefore, the HTTP protocol is said to be ???stateless;??? i.
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