Re: What's wrong with autonegotiate

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Date:         Fri, 16 Jan 2004 11:43:00 -0500
To: aix-l@Princeton.EDU

Since I started this question, it seems I should end it. No need for
replies or a "holy war".

We autonegotiate EVERYTHING outside of our server rooms. But we even
autonegotiate some of the servers too.

Why?
Does it improve performance, assuming it works as designed? Not really.
No faster. But it frees up ever having mismatched settings. Better yet,
it allows our GREAT network team the freedom to replace or upgrade network
cards in our multitude of hubs without fear of getting all the ports back
to some varied settings.

Is it worth it?
If it works as designed, very much so.

How is autonegotiating working for us?
I have known for a good while that I have a great network and a excellent
network support team. After seeing the answers to this question from so
many different people, how they have had such bad results with
autonegotiating, I went to my network team and asked them what is the
story. It appears that not only do we have an extremely excellent group of
professionals in our network team, but they have not left any stones
unturned and they have not let any of our network hardware suppliers off
the hook until every issue is resolved. They also monitor the network
24x7x365.25.

So, have we had no problems with autonegotiating and/or other network
issues? Of course we have. But we stay on top of them and get them
resolved. And, YES, we do have some equipment that "could" autonegotiate
but is locked down at 100/Full because it does not behave - but that is a
small minority. Of course we have some 10 Mbit and some half duplex
equipment that we set as needed. We also have a rapidly growing pool of
Gigabit systems (copper and fiber). Also, I must add that we do NOT
autonegotiate between network hubs.

So why am I bragging here like this? Am I trying to tick-off those who
believe the other way? NO!! I just feel that for those who have not made
the decision or have wondered if autonegotiation can work, there is at
least one site that has made it work.

Thanks for such great replies to this question. And thanks for opening my
eyes to how good my network team really is.

Sincerely,

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

=================================================
Contains Confidential and/or Proprietary Information.
May not be copied or disseminated without the expressed
written consent of The Goodyear Tire & Rubber Company.
=================================================

                      Peter McKay
                      <Peter.McKay@INFI To: aix-l@Princeton.EDU
                      NITY.CO.NZ> 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 05:03
                      PM
                      Please respond to
                      IBM AIX
                      Discussion List

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

=================================================
Contains Confidential and/or Proprietary Information.
May not be copied or disseminated without the expressed
written consent of The Goodyear Tire & Rubber Company.
=================================================

                      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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