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This is probably a question, but it isn't online yet.

The PHY on my NIC is blinking on and off ridiculously, and it should always be on. I googled it and found no answers, just questions.

This is on Linux (Ubuntu 8.10) with a Broadcom 100Base-T NIC:

lspci output: 01:09.0 Ethernet controller: Broadcom Corporation BCM4401 100Base-T (rev 01)

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Somewhere in my googling for a solution I came across ethtool. I decided to try disabling the pause auto-negotiation after perusing its man page...

ethtool -s eth0 autoneg off

So far so good; the PHY is not being turned off. I added this command to /etc/rc.local for now, but perhaps there is a better place.

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In that case there's most likely a faulty cable and/or switch (possibly just one port). Try swapping them just in case. – LapTop006 Jun 20 '09 at 10:54
Turns out the ethtool idea doesn't work. I tried a new cable, and a different port on my switch, but that doesn't solve it either. I guess I'll put a different NIC in this server. – Jerry Penner Jun 24 '09 at 3:18
The new NIC with the original cable and switch port work flawlessly. No more messages in /var/log/messages: Jun 23 21:08:17 banjo kernel: [ 404.496415] b44: eth0: powering down PHY Jun 23 21:08:17 banjo kernel: [ 405.000090] b44: eth0: Link is down. Jun 23 21:08:20 banjo kernel: [ 408.000092] b44: eth0: Link is up at 100 Mbps, full duplex. – Jerry Penner Jun 24 '09 at 5:35
Here is the Ubuntu bug report for the Broadcom driver: – Jerry Penner Jun 24 '09 at 5:40

You probably checked this already, but since you didn't mention anything about this... is your networking cable alright? This is usually a symptom of a bad physical connection (cable or connector).

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