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Re: ethernet configuration

On Wed, Jul 02, 2008 at 10:43:58 +0300, Andrei Popescu wrote:
> On Tue, Jul 01, 2008 at 06:04:17PM -0300, André Timpanaro wrote:
> > I've found the /etc/udev/rules.d/z25_persistent-net.rules file:
> > 
> > # This file was automatically generated by the /lib/udev/write_net_rules
> > # program, probably run by the persistent-net-generator.rules rules file.
> > #
> > # You can modify it, as long as you keep each rule on a single line.
> > # MAC addresses must be written in lowercase.
> > 
> > # PCI device 0x10de:0x03ef (forcedeth)
> > SUBSYSTEM=="net", DRIVERS=="?*", ATTRS{address}=="00:00:6c:e9:01:77",
> > NAME="eth0"

[ snip: eth1 - eth7 ]

> > # PCI device 0x10de:0x03ef (forcedeth)
> > SUBSYSTEM=="net", DRIVERS=="?*", ATTRS{address}=="00:00:6c:32:fa:60",
> > NAME="eth8"
> I've heard here that some (all?) nVidia chipsets will change MAC on 
> every boot. That's your problem.

IIRC, certain versions of the forcedeth driver have a bug and cannot
determine the real MAC address of the device. To compensate for this, a
semi-random MAC address is chosen that is formally correct for nvidia
(00:00:6c plus three random bytes). The idea is to minimize the chance
that two nvidia devices on the same local network get the same MAC
address. This behavior is unfortunately not really compatible with the
design philosophy of udev.

> You can look in the BIOS for a setting to have a persistent MAC or 
> rewrite the rule to allocate device names based only on the kernel 
> module (forcedeth?).

You could try to use a wildcard in z25_persistent-net.rules. This might
work as long as you don't put a second nvidia network card into this

# PCI device 0x10de:0x03ef (forcedeth)
SUBSYSTEM=="net", DRIVERS=="?*", ATTRS{address}=="00:00:6c:*", NAME="eth0"

To make sure that the rest of your network sees a consistent MAC address
for this computer, try to set it explicitly in the eth0 stanza of

# The primary network interface
allow-hotplug eth0
iface eth0 inet dhcp
    hwaddress ether 00:00:6c:e9:01:77

Regards,            | http://users.icfo.es/Florian.Kulzer
          Florian   |

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