Re: What's wrong with autonegotiate

From: Hunter, Mark (Mark.Hunter@ANHEUSER-BUSCH.COM)
Date: Wed Jan 14 2004 - 12:18:15 EST

We have the issue on cabletron and cisco both.
10/100 we have fixed speed/duplex,
1000 works fine autonegotiate.

Mark Hunter

-----Original Message-----
From: cbaker@GOODYEAR.COM [mailto:cbaker@GOODYEAR.COM]
Sent: Wednesday, January 14, 2004 10:48 AM
To: aix-l@Princeton.EDU
Subject: Re: What's wrong with autonegotiate
Importance: High

Folks,

Thanks for the overwhelming reply to this question.

Could the issue be that Cisco is not talking the "preferred" way? Seems to
be a common thread in most of the replies. I believe Cisco 10/100BaseT
ports use a different negotiation method than Enterasys and other PCI NIC
cards (NWAY, I think).

Also, I am speaking of workstations, desktops, PC's, printers, etc. - Not
necessarily servers.

Does anyone have experience on non-Cisco equipment?

Christopher M. Baker
Senior Technical Support Analyst
DSE/TCO
Goodyear Tire and Rubber Company

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                      Thierry ITTY
                      <thierry.itty@BE To: aix-l@Princeton.EDU
                      SANCON.ORG> cc: (bcc: Chris
Baker/NA/GDYR)
                      Sent by: IBM AIX Subject: Re: What's wrong with
autonegotiate
                      Discussion List
                      <aix-l@Princeton
                      .EDU>

                      01/14/2004 04:18
                      AM
                      Please respond
                      to IBM AIX
                      Discussion List

I consider that a autonegotiated connexion that works fine is just a matter
of luck

I had problems with many kind of OSes, NICs, switches.

the main problem with autonegotiation is that it never doesn't work. it
always works, but only at some percentage of the nominal throughput,
depending on the traffic profile. it may work fast in one way but very slow
in the other (ie upload vs download) or it may be fast with one protocol
and slow with another (ie telnet vs ftp). and so on. it may be fine with
one nic connected to one switch, then bad if you change the switch.

I personnaly strongly advise to disable autonegotiation and setup fixed
duplexity and speed on all nics and all switch ports

A 15:17 13/01/2004 -0500, vous avez écrit :
>I have noticed lately that some still say in this site "DO NOT
>AUTONEGOTIATE your speed/duplex on IBM AIX boxes.
>
>We had major problems with that back in the early AIX 433 (or earlier)
days
>and back with the 43P-140 [7043-140] (and first cut of the 150's and
260's)
>and the first auto-negotiating ethernet cards.
>
>BUT, we were told that with the newer boxes (about the time when they went
>from beige to black cases) that the problem was fixed. It was NOT an OS
>issue but rather a NIC issue.
>
>In our case, we had (and still have) a lot of EnteraSys (Cabletron)
>switches. We were told that the "world" used one negotiation schema (i.e.
>Cabletron, HP, SUN, SGI), but IBM was using a different method in those
>ethernet cards. So, we saw that the NIC and the network hub/port were
>never coming to an agreement at what speed and duplex to use. So, we
>ticked off our Network group and made them lock down the ports to
100/Full.
>
>But, since then, (a couple years now at least) we have been setting both
>the NIC and the network port to autonegotiate and have had no problems.
>

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