Questions on network transfer rates

[Donald D Rice]

I'm trying to find some practical estimates of how fast data can be moved over
a tcp/ip ethernet (10 Mbps).  I ran some tests with two DS5000/Ultrix 4.0
machines connected only to each other with no other users to get an idea
of how fast they could transfer data.  For a test file, I used a 10.8 MB
data file.  The results I got were:

	NFS cp:		410 kB/s
	FTP:		395 kB/s
	TFTP:		178 kB/s

Questions:
1) I thought that for a clear 10 Mbps tcp/ip link, the data transfer rate would
   be on the order of 1 MB/s (data, not counting packet headers and such).  If
   that is too optimistic, why?  If it is realistic, why are the workstations
   putting out at less than half of the maximum speed?  In the latter case,
   connecting FDDI directly to the workstations would seem pointless.
2) I was surprised that NFS cp did so well.  Under normal network conditions,
   cp is always slower than FTP on our machines.  One time when the network was
   fairly busy, FTP moved the test file at 240 kB/s (60% of maximum rate),
   while NFS cp moved the file at only 8.1 kB/s (2% of maximum?!).  Is that
   kind of degradation normal for NFS, or does it suggest a problem with our
   configuration?
3) I was also surprised that TFTP was so slow compared to FTP.  We normally
   have TFTP disabled, but I turned it on for these tests because I thought
   its simpler transfer mechanism would give faster transfer rates.  Why
   not?
4) Has anybody else run tests like these for other machines?  I'd be interested
   to see how different combinations of PCs/software/network cards work out.

Any insights or information along these lines would be appreciated.

(PS: apologies if this gets out more than once.  The first post vanished,
and this one is coming from a new nntp client...)

Thanks,
-- 
Don Rice                                  Internet: ddr at flux.isr.alaska.edu
Geophysical Institute                     E-mail:   fnddr at alaska.bitnet
University of Alaska                      Phone:    (907) 474-7569
Fairbanks, AK 99775                       Loran:    64.86N 212.16E