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Switch port not Auto Negotiating

Jonathan Axford
Trusted Contributor

Switch port not Auto Negotiating

Hi,

I have a small issue with 1 port in a 4108gl switch.

The switch is using J4862A 24 port 10/100 modules.

On port G24, the switch will only communicate with the host (My laptop) when set to Speed-duplex 100-full. For some reason it will not auto negotiate. All of the other ports on the switch are set to the default Auto.

Any one seen this before? I have tried other devices and it will not auto negotiate with anything so its not the fault of the laptop.

Cheers
Where there is a will there is a way...
10 REPLIES
Ronnie Hamilton_1
Frequent Advisor

Re: Switch port not Auto Negotiating

take it your laptop is set to auto .

it may be a faulty port on that module.
Les Ligetfalvy
Esteemed Contributor

Re: Switch port not Auto Negotiating

I have to ask...
Did you check the settings on the switch to make sure auto is not turned off for that port?
Ari Yrjölä
Advisor

Re: Switch port not Auto Negotiating

I've noticed some strange negotiation problems with the latest firmware G7.93 in a 4108gl. In our case it's the opposite; forcing speed&duplex does not work.

We have also the last port on a module (B24) connected to Procurve 2650 port 49 (that other 10/100/1G one), and after upgrading firmware on both switches (H8.86 now on 2650) the link would not come up, although both ends were forced 100FD, which did work with previous firmwares. It has been working only after setting port 49 to Auto-100 and B24 to Auto.
rick jones
Honored Contributor

Re: Switch port not Auto Negotiating

Just to add to the possibly silly questions :)

Autoneg has to be on on _both_ sides.

Some boilerplate:

$ cat usenet_replies/duplex
How Autoneg is supposed to work:

When both sides of the link are set to autoneg, they will "negotiate" the duplex setting and select full duplex if both sides can do full-duplex.

If one side is hardcoded and not using autoneg, the autoneg process will "fail" and the side trying to autoneg is required by spec to use half-duplex mode.

If one side is using half-duplex, and the other is using full-duplex, sorrow and woe is the usual result.

So, the following table shows what will happen given various settings on each side:

Auto Half Full

Auto Happiness Lucky Sorrow

Half Lucky Happiness Sorrow

Full Sorrow Sorrow Happiness

Happiness means that there is a good shot of everything going well.
Lucky means that things will likely go well, but not because you did anything correctly :) Sorrow means that there _will_ be a duplex mis-match.

When there is a duplex mismatch, on the side running half-duplex you will see various errors and probably a number of late collisions. On the side running full-duplex you will see things like FCS errors.
Note that those errors are not necessarily conclusive, they are simply indicators.

Further, it is important to keep in mind that a "clean" ping (or the like - eg "linkloop") test result is inconclusive here - a duplex
mismatch causes lost traffic _only_ when both sides of the link try to speak at the same time. A typical ping test, being synchronous, one at a time request/response, never tries to have both sides talking at the same time.
there is no rest for the wicked yet the virtuous have no pillows
Jonathan Axford
Trusted Contributor

Re: Switch port not Auto Negotiating

Hi Guys,

Cheers for the info, When i tested it both sides were set to auto negotiate. The port will still only work if the switch is set to 100-full. I am not too worried about it though as the connection does work...

Where there is a will there is a way...
rick jones
Honored Contributor

Re: Switch port not Auto Negotiating

Apart from auto being on on both sides, is the cable "known good?" If you move the cable to another port on the switch does it negotiate? If you plug another system into port 24 does it negotiate? Is the NIC/driver combo in your laptop unique to the switch - or are there others with the same NIC _and_ driver that negotiate successfully?
there is no rest for the wicked yet the virtuous have no pillows
Jonathan Axford
Trusted Contributor

Re: Switch port not Auto Negotiating

Hi again,

The cable appears to be fine, If i use it in another port it negotiates without a problem. If i plug another computer into port 24 with a differnet NIC then it fails to negotiate!

I am the only device on that switch with the Driver/NIC combo i have as mine is just a laptop that i use for maintenance, all of the other devices are desktop PC's. I have never had a problem auto negotiating on any of the switches that we have at the college until this one!

Where there is a will there is a way...
rick jones
Honored Contributor

Re: Switch port not Auto Negotiating

Well, if the laptop negotiates with another port on the same switch, and the cable is good, and other "known good" systems will not negotiate with the port, and you are certain that the port is set for autoneg then the only remaining conclusion I can think of is that there is something wrong with the specific port's hardware. Maybe the PHY is fubar or something.

There is I suppose still the chance that it is firmware related, but I would have expected that to afect all ports not a specific port.

there is no rest for the wicked yet the virtuous have no pillows
Jonathan Axford
Trusted Contributor

Re: Switch port not Auto Negotiating

I am going to go over at some point this week and double check everything, Haven't had much time this week, But i will let you knwo the outcomes....
Where there is a will there is a way...
Anders_35
Regular Advisor

Re: Switch port not Auto Negotiating

Sadly, this is not an uncommon situation.
For all our 100mbps equipment we lock all switchports to 100 full. Autonegotiation just doesn't work, a lot of the time. I've seen this happen on Nortel, Cisco and HP switches.
Never figured out why.