Comments on: Blessay: Autonegotiation on Ethernet — It Works, It Should Be Mandatory!

By: Cisco tips: Track down communication issues – Part 1 | FirstDigest

Cisco tips: Track down communication issues – Part 1 | FirstDigest — Mon, 15 Mar 2010 19:18:21 +0000

[…] b) Check speed and duplex settings –if you have auto-negotiation here and it fails, you will end with an interface in down status –again if you have static settings here, check to be the same on both sides. –for more pro and cons regarding auto-negotiation vs static, please see Greg Ferro’s article […]

By: Jim

Jim — Mon, 15 Mar 2010 14:28:28 +0000

The acid test — get the same problems booting BSDs/Solaries/Linux kernels?

–if yes, suspect hardware or physical layer
–if no, contact Microsoft/HP/whoever for your support

We’ve never had a auto-neg fail under a non-Microsoft OS on a desktop or workstation machines. Even the so-called “WHQL” drivers give regular trouble with auto-neg, especially to Cisco kit.
(my angle — as a software-to-OS-to-hardware compatability clearing/proving house, we link up and tear down workstations at the rate of 600+ a day, for around two week cycles, 52 weeks a year, across 3 continents)

By: Calin

Calin — Mon, 15 Mar 2010 11:34:59 +0000

It’s nice to see people getting involved and discussing pro and cons of using either one way or another. I have read your thoughts and I agree that network engineer should push autonegotiation in the network, where it’s possible, but let’s not forget that in many cases “paper talk” and how the things behave in the real environments it’s different.
I always receive instructions from the server team when adding a new device, to configure the port on xxx speed and full duplex. In some cases I wanted to test what’s going on and I let the ports on auto and did just fine, but sometimes it’s not working at all. It’s true also that I don’t know how new or old is the device at the other end of the cable.
I agree 99% with this article, just the following phrase give me a dark view of a network: “If you haven’t already, you should consider changing your standards to use auto-negotiation everywhere because it is a prerequisite in the new technology.” I imagine a new network engineer that goes there and issue a interface range command on all switches and apply auto negotiation without being aware of the problems that might appear. He will be “crucified” for making an interruption on the services due to auto negotiation failure.
After all, when nothing is working, you can also blame the networking

By: Greg Ferro

Greg Ferro — Fri, 12 Feb 2010 16:32:35 +0000

By Crom, you missed the point completely. The first paragraph clearly says it was a problem (when I was a younger engineer) then I say it isn’t a problem any more.

The most likely cause of the duplex mismatch today is faulty cable. Not a hardware problem with Nortel, 3Com or anyone else. And I explain the negotiation process so that you can understand why.

Of course, you are smarter than Cisco, Sun, Dell and many other people because you don’t believe or even mention the evidence presented here.

I don’t have a very high opinion of your company and you are confirming that very concept. Please pay attention and read the article before you criticise.

By: pete bateman

pete bateman — Fri, 12 Feb 2010 16:12:17 +0000

I would suggest that your experience is all quite recent. In the early days of full duplex Ethernet and Fast-Ethernet interoperability between various manufacturers implementations of the standard was pretty bad. I.E a 3com Nic to 3com switch might be fine. Plug a Nortel router into your switch and it would all go south. I have personally seen this many times. Us old hands got bitten by this so often that we always recommend nailing the port config down on interlinks and servers. i.e. if a desktop coems up wrong its a minor issue, if you server suddenly decides its going to be half-duplex you are in deep whatsits. I have seen this happen. More recently you are right, it generally just works, but don’t tell everyone that its infallable,cos it ain’t.

By: Autonegotiate – The debate continues « Bridging the gap between CCIE RS and SP

Fri, 15 Jan 2010 23:19:51 +0000

[…] die hard holds true to this one. Quite a while ago I read an article by Greg Ferro regarding the force speed and duplex myth. Today I stumbled on Terry Slattery’s blog regarding the same “autonegotiate duplex or […]

By: joe

joe — Fri, 27 Feb 2009 04:58:29 +0000

I come from the telco world and school of hard knocks. Yes, if the pairing of equipment requires auto, or if we are talking Gigabit ether, then you must auto.

Denis hits the nail on the head, you have an unplanned reboot, then the sucker goes to some crappy setting, and no one notices until the business day hits. The throughput sucks, and the issue can be transient in nature. Once you figure out auto bit you in the ass one more time, management says “Damn it, turn off auto”. As as management usually has a few more gray hairs, they still remember the bad old days.

So in the real world, non-gigabit will be explicitly set if you want to keep your job.

A red herring, some folks will say you can’t manage all the settings with out provisioning errors. That is a gap in your server management process, not a a byproduct of explicit settings. Are your configuration files in /etc set to “auto”? I don’t think so.

By: David Sudjiman » Blog Archive » Thou Shalt Use Auto-Negotiation!

David Sudjiman » Blog Archive » Thou Shalt Use Auto-Negotiation! — Fri, 02 Jan 2009 08:18:59 +0000

[…] Greg Ferro posted a nice write-up about Autonegotiation on Ethernet — It Works, It Should Be Mandatory! […]

By: Pushkar Bhatkoti

Pushkar Bhatkoti — Wed, 12 Nov 2008 12:26:35 +0000

good research. The point is if any vendor doesn’t follow the standard it’s not your fault. Your concept still works e.g. leave auto-neg on.

well written.

–Pushkar Bhatkoti

By: Greg Ferro

Greg Ferro — Tue, 28 Oct 2008 22:46:24 +0000

I have had all sorts of problems, but ultimately, auto-neg is the best default condition. I move to hard-config when there is a problem. That is my recommendation to everyone.

By: Tim

Tim — Sat, 25 Oct 2008 22:53:32 +0000

If only the world was that perfect Greg

I’ve had LOADS of problems with autoneg.
I’ve NEVER had a problem where both ends are properly nailed.

No-brainer IMHO, why take the chance? Especially if you don’t have access to both ends to check that it auto’d correctly _this_ time. (Just ‘cos it got it right last time doesn’t mean that it will again)

I concede Gig is very different and shouldn’t be tared with the same brush.

Tim

By: Dennis

Dennis — Thu, 16 Oct 2008 20:37:37 +0000

Why do I want to hard set EVERY 10/100 port in the network?

1) Last week, Cisco 2950 switch and Cisco 2800 router both powered up after an outage. Cisco did not successfully autonegotiate with Cisco switch. Worked well enough that no one noticed til trading started over that link.

2) Panasonic Toughbooks, circa 2004/5, and Cisco 4500 10/100 port. Don’t remember the ethernet chipset vendor for the Panasonics offhand. Would not ever, under any circumstances, negotiate properly. We had over 100 of those laptops in our company. PITA!

As you say, Gig is a different animal, but hard setting speed/duplex is a good practice, learned by many of us in the school of hard knocks.

m00tpoint

By: Dmitri

Dmitri — Mon, 13 Oct 2008 23:17:56 +0000

Flow control on GigE ports on 3550 sucks. It starts sending pause frames *way* before a link starts approaching full capacity. Not sure about other equipment, but the said experience with 3550 did not make me happy (and aware).

By: Scott

Scott — Thu, 25 Sep 2008 21:15:40 +0000

I work at a major vendor of server application software that pretty much requires GigE throughputs, and while I agree with you in theroy, the practical is that it doesn’t work that way in the real world. There are two hardware vendors that make 90% or better of server NICs and only a handful of vendors who make 90% or better of the switches out there. The combinations of several of these simply do not work when set to full Auto on both sides. If there was better enforcement of the IEEE standards, we could all play in your ideal world. But the truth is that many of these vendors in question need serious help. I don’t know how they can get away with charging server NIC prices in NICs that have the same bugs (or worse) than simple desktop NICs.

By: zakki a

zakki a — Tue, 26 Aug 2008 08:24:06 +0000

Greg,
Great article. In term of standard, yes auto negotiation the first we have to try. but auto negotiation failure is not a myth. it is true.