# Help: iMac has 10% packet loss...I think its the ethernet card



## Fahrvergnuugen (Feb 25, 2003)

My friend has an iMac running OSX.2. its a blue dalmation. Its on a college network at RIT. There are 3 other computers in the same apartment on seperate ethernet jacks and they do not have any problems.

I am testing the connection by flood pinging rit.edu [which is on campus] as well as her roomates computers. It gets between 10 and 15% packet loss to all of them. Pinging rit.edu from her roomates' machine has 0 packet loss.

I have tried switching ethernet jacks and ethernet cables.

To me it seems like something just randomly went wrong with the ethernet port on the iMac.
Is there anything else I can test to be sure?
If it is the ethernet port, what can be done about it? Do they sell USB ethernet adapters? Or would it be cheaper to get it fixed?


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## hunt045 (Feb 25, 2003)

I believe that the ethernet port is built in as part of the motherboard.  Have you investigated the firmware version of this particular machine?


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## Fahrvergnuugen (Feb 25, 2003)

as far as i know all the ethernet ports on newer macs [2000+] have on board ethernet.

why would the firmware matter?

I forgot to mention, it was working absolutely fine and then about 2 weeks ago it started doing this crap.


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## Fahrvergnuugen (Mar 9, 2003)

anybody else have any ideas?


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## theed (Mar 9, 2003)

yeah, Mac OS X drops packets on a flood ping.  Seriously, yell at Apple.  I have a dual G4 running OS X, a 233MHz laptop running OS X, and a 400MHz G4 running openBSD.  openBSD doesn't drop any packets and has a faster turnaround time.  Mac OS X drops packets.  On a perfect network with high throughput it seems that Mac OS X drops ~50% of the packets.


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## Fahrvergnuugen (Mar 10, 2003)

That may be true.... but this imac also drops the same average amount of packets with regular pings too.

Its impossible to load webpages or use services such as AIM. The only thing that you can do with it is establish a telnet connection to another machine....then after a few seconds the connection goes AWOL


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## Fahrvergnuugen (Mar 10, 2003)

tiffimari.rh.rit.edu if you're interested


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## davidbrit2 (Mar 10, 2003)

Hmm, could there be corrosion building up in the network jack? Turn off the computer and unplug it (very important,) and try cleaning off the pins with a cotton swab gently dampened with isopropyl alcohol. Wipe up the excess with a dry swab and see what happens. You might want to let it sit for a few minutes to make sure it's dry before you turn it on.


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## Fahrvergnuugen (Mar 10, 2003)

I looked for that, but the light was very dim... I'll try some alcohol, its worth a shot.


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## Ripcord (Mar 12, 2003)

Any chance that you've hardcoded the iMac interface to full-duplex, but you're plugged into a hub, or a switch that isn't ALSO configured to full-duplex (it's configured to "auto-negotiate"?  If so, you have duplex mismatch, and this will cause packet loss all over the place...


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## Fahrvergnuugen (Mar 12, 2003)

I don't believe so...... I installed OS9 on my iPod and booted the imac to that and it had the same problem....wouldn't the duplex settings be reset to default if I booted to a different OS?

Also, I tried pinging itself....what exactly happens to the packets when you ping a maching from itself? [I'm pinging 129.21.142.29 not 127.0.0.1]. It doesn't drop any packets when I do this.

On a side note, I have not been able to find a USB Ethernet adapter that works with OSX...I don't think one exists.

I called an apple service store and its going to be 250 dollars just for the logic board. And it seems like the cheapest I could possibly get an airport setup for it is 200 bucks. Very very crummy


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## itsasony (Mar 15, 2003)

I saw a blue and white G3 desktop Mac with crushed pins in the RJ45 port and it exhibited interrupted network access by the normal vibration of the power suppy/hard drive/CD. Not until i used a very precise set of electronics pliers to pull the pins forward at a better angle did the problem stop.


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## Fahrvergnuugen (Mar 20, 2003)

> _Originally posted by Ripcord _
> *Any chance that you've hardcoded the iMac interface to full-duplex, but you're plugged into a hub, or a switch that isn't ALSO configured to full-duplex (it's configured to "auto-negotiate"?  If so, you have duplex mismatch, and this will cause packet loss all over the place... *



how exactly do i change the duplex settings of the ethernet port on the mac? i'm willing to try anything at this point...


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## bobw (Mar 20, 2003)

Take a look here


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