mccallum@opus.UUCP (Doug McCallum) (04/16/84)
Actually, IEEE 802 hasn't abandoned the principle, they just complicated
it. I personally don't see the need for something this complicated.
It is expected that 802.3 (the physical layer) be supported with 802.2
(the link layer protocol). The headers of 802.2 do provide the necessary
information to allow multiple higher level protocols to exist. One thing
802.2 does show is that there are still a lot of people who don't want
datagram service. While there is an unacknowledged, connectionless service
in the link layer, there is also a connection-oriented service which provides
link layer sequencing, flow control and error recovery, all the things now
done in TCP and other transport protocols.
The connection at the link layer seems to be in keeping with the ISO approach
to networks. The ISO protocols want connection negotiation done at every
layer.
As far as hardware compatibility is concerned, Rob is correct. With the
correct set of options, 802.3 is within the ethernet spec. 802.3 is a
standard for a family of network hardware with different speeds and addressing.
For example, 802.3 provides both 16 bit and 48 bit network addresses but within
a network the addresses must be the same length.
Doug McCallum
{allegra,ucbvax,amd70,hao}!nbires!mccallum