I'm also one of the people who always hard sets both ends to 100 full on
servers.  In my experience with auto-negotiate, things look fine and dandy
when looked at quickly, i.e. link lights at 100 and FD and data passing
fine, but problems seem to occur under heavy load.  I noticed slight
throughput problems only after really stress testing the links with large
FTP transfers.  Monitoring the port on the switch would show several CRC
errors, bad headers, etc., much more than "normal".  Also placing a sniffer
directly on the server in question would eventually show dropped frames due
to hardware errors.  Most errors wouldn't occur until transfer rates
starting exceeding the 14-15 mb/s range, which is where throughput would
pretty much max out.  Hard setting both ends eliminated all the errors and
increased the transfer throughput at least 3 fold, in the best cases.

I included a variety of vendors in testing:
HP and IBM server hardware
IBM, HP, 3COM, and Intel nics
IBM, HP, and Cisco switches

Some equipment did auto-negotiate well together, most of what I gathered
seemed to depend most upon the switch vendor, more than any other factor.
I have actually had the best luck with Cisco switches and Intel nics, both
latest and greatest models.  It seems to work well for the desktops, I
don't mess around hard setting those.

My advice would be test it yourself.  Raw results will prove the best
settings in your environment.


===========================================
    John Monahan
    Network Administrator
    Liberty Diversified Industries
    (763) 536-6677
===========================================




                    Jeff Connor
                    <connorj@NIAGARAM        To:     ADSM-L AT VM.MARIST DOT EDU
                    OHAWK.COM>               cc:
                    Sent by: "ADSM:          Subject:     Auto-negotiate 
setting for NIC's
                    Dist Stor
                    Manager"
                    <[email protected]
                    .EDU>


                    09/14/00 01:21 PM
                    Please respond to
                    "ADSM: Dist Stor
                    Manager"





     Over time I've seen posts on this listserv about not using
auto-negotiate for network interface cards and hard coding the
line speed like 100mbit full duplex.  They use auto-negotiate on
all of our Compaq Windows NT servers here and can't help but
wonder, based on posts on this listserv, whether our server NIC's
are really running at 100mbit full duplex.  I asked one of our NT
admins to check one of our servers. They used Comaq's Insight
Manager software which showed the NICS at the correct speed.
Could it be lying?  Can any of you that have had problems with
auto-negotiate, even better with Compaq servers, share your
experiences?


Thanks,
Jeff Connor
Niagara Mohawk Power Corp.