Re: What's wrong with autonegotiate

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Date:         Thu, 15 Jan 2004 11:03:35 +1300
To: aix-l@Princeton.EDU

Good people,

In every instance where Auto negotiate has been set in the environments that I have been involved with, there have been major problems with network reliability. In EVERY case (whether the switches were Cisco, 3COM, D-Link, or NetGear) turning off auto negotiate for 10/100 connections and forcing 100/Full for ALL servers regardless on OS is the only way to ensure a stress free life. My standard AIX build documentation states that the ethernet cards are fixed at the desired speeds (except Gb) as the first step after the OS installation and before applying patches and connecting to a LAN.

My understanding (maybe a networking GURU can confirm or elaborate) is that the standards for auto negotiation of 10/100 LAN's are quite loose in the way that they have been applied. And that every vendor "improves" their switches/LAN cards and the result is that the standards are broken.

To summarise:

        Servers (All OS's): Fix the ethernet speed!
        Administration Workstations: Fix the ethernet speed!
        Print Servers: Auto negotiate!
        Workstations: Auto negotiate!

The goals are twofold:

        (1) Make the server connections reliable/fast
        (2) Make the LAN/WAN administration simple

As usual named brands (Cisco, 3COM etc) are the best to choose, however piloting the environment is crucial in EVERY case. Where possible standardise on ONE vendor!

Kind regards,

Peter McKay
Technical Consultant

Infinity Solutions Ltd
PO Box 2640, Christchurch
Ph: 03 963 7965, Mob: 027 230 1884
Fx: 03 963 7941
www.infinitysolutions.co.nz

-----Original Message-----
From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] On Behalf Of cbaker@GOODYEAR.COM
Sent: Thursday, 15 January 2004 5:48 a.m.
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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• Previous message: Debby Smit: "Re: What's wrong with autonegotiate"
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