University of California at Berkeley has been funded by
DARPA to modify the Unix system in a number of ways.
Included in these modifications is support for the Internet
protocols. In earlier versions (e.g. BSD 4.2) there was
good support for the basic Internet protocols (TCP, IP,
SMTP, ARP) which allowed it to perform nicely on IP ether-
nets and smaller Internets. There were deficiencies, how-
ever, when it was connected to complicated networks. Most
of these problems have been resolved under the newest
release (BSD 4.3). Since it is the springboard from which
many vendors have launched Unix implementations (either by
porting the existing code or by using it as a model), many
implementations (e.g. Ultrix) are still based on BSD 4.2.
Therefore, many implementations still exist with the BSD 4.2
problems. As time goes on, when BSD 4.3 trickles through
vendors as new release, many of the problems will be
resolved. Following is a list of some problem scenarios and
their handling under each of these releases.