Ethernet on pdp11/70's

[minnie.ccsteve at ucb-vax.ARPA]

From:  Steve Nichols <ucdavis!minnie.ccsteve at ucb-vax.ARPA>

	Does anyone out there have experience with running ethernet hardware
on an 11/70?  We will soon be installing an ethernet on vaxes running both
vms and unix.  We currently have 4 pdp11/70's running unix (soon 2.9 bsd).
We would like to put these pdp's on the ethernet also, but other than the 
problems with tcp/ip software in 2.9bsd we have anther concern.
	We are concerned that a 10mb ethernet board will swamp the unibus 
because we already have 3 dh's, a line printer, and the console on the unibus. 
All our disks and tapes are on the massbus.  In some cases the unibus may also
contain a dual floppy, a phototypesetter, or a dmc11.  We are able to support 
around 30 simultaneous users per machine and we want to continue to be able to
support that many even running ethernet.
	We currently have Berknet running over 9600 baud rs232 lines and 56kb
dmc11's as our network.  I guess the questions come down to: 
1)	Will the overhead from running ethernet be significantly greater than 
	the overhead running berknet?
2)	Will we still be able to support at least the same number of users
	while running ethernet as while running berknet?

							Thanks,
							Steve Nichols
							ucbvax!ucdavis!ccsteve