ethtool/nic question

[Darrell Michaud]

Once the gig-E cards have dropped down to 100 for a valid reason,
sometimes it is tricky to induce them to renegotiate up again. If they
don't handle it automatically or with something like ethtool or a
manufacturer's utility, you might try removing the kernel module drivers
and re-adding them after switching ports, port configuration, or cables.
Sometimes this isn't enough, because of firmware bugs or something
happening at the hardware level. In this case one workaround is to fully
drain power to the card and then repower it.

Do either of your NICs support booting from the LAN? If they do (and
sometimes even if they do not) the NICs will fully power on and negotiate
a link before Linux is up. Sometimes (with Wake on LAN) the NICs will be
fully powered as long as there's electricity on the motherboard,
regardless of whether the system is on or not. You can check the lights on
your interface or switch to see if it's recognizing 100bT or 1000bT. If
you can do this and remove the OS as a variable, it might make your
troubleshooting easier.


bruce.labitt at autoliv.com wrote:
> I have a switch between the two computers I am trying to interconnect. The
> remote computer comes up as gig-E.  The local computer, connected to
> either port, seems to come up as 100M.  I have tested the switch by
> swapping ports - I know the switch is ok.  (The gig-E indicator follows
> the remote switch.)   I also tried a different CAT6 cable, still no joy.
>
> To make sure I haven't messed anything totally up, is there a way to set
> the NIC's back to their normal mode.  Are the setting for ethtool
> persistent?
>
> # ethtool -s ethX autoneg on  ?
>
> Anything else?
>
> -Bruce
>
> "Darrell Michaud" <dmichaud at amergin.org> wrote on 10/06/2008 01:45:09 PM:
>
>> I'm sure there's other advice out there but I'll throw in:
>>
>> Don't change the linux broadcom or intel gig-E ethernet drivers from
> their
>> defaults without a specifically documented reason. They will
> autonegotiate
>> to 1000 when possible under normal circumstances.
>>
>> Check your wiring, your switch, your switch's configuration first. My
>> personal experience is that GigE automatically dumbing down from 1000
>> to
>> 100 has not been due to an configuration issue in the linux drivers.
>>
>>
>>
>>
>>
>> bruce.labitt at autoliv.com wrote:
>> > What has your success been with ethtool?  I cannot determine if I have
> a
>> > software (ethtool) or hardware issue.
>> > I cannot set either ethernet adapter I have to 1 Gbit.  I have a
> Broadcom
>> > NetXtreme BCM5754 Gigabit Ethernet PCI express and a Realtek RTL-8169
>> > adapters in my box.  The Broadcom is integrated in the mobo.
>> >
>> > From google I know that people have had issues with the 8169's.  Some
>> > folks have trouble and others don't.
>> >
>> > My distro (still Sci Linux) have only version 5 of ethtools.  I just
> built
>> > version 6 of ethtools and it does not seem to make a difference.  I
> can
>> > supposedly set the speed and "it allows it", but querying the device
>> > results in the report of the speed not being set to 1000 Mbit.  The
> 1Gbit
>> > link light does not go on.  I cannot set either interface to 1Gbit,
> even
>> > with autoneg off.
>> >
>> > Any suggestions?  Buy another NIC?  Not really a problem - which one?
> I
>> > was leaning towards intel, but I read of their firmware being able to
>> > brick itself.
>> >
>> > -Bruce
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