[CentOS] again, nic driver order

Rob Townley rob.townley at gmail.com
Sun Nov 29 08:27:43 UTC 2009

On Sat, Nov 28, 2009 at 2:55 PM, Ross Walker <rswwalker at gmail.com> wrote:
> On Nov 28, 2009, at 3:10 PM, Les Mikesell <lesmikesell at gmail.com> wrote:
>> Tom H wrote:
>>>>>> Digging around google a bit more I came up with different rules,
>>>>>> and
>>>>>> fingers crossed, they seem to work!
>>>>>> SUBSYSTEM=="net", SYSFS{address}=="00:1b:21:4d:c3:e8", NAME="eth0"
>>>>>> # pro/1000gt
>>>>>> SUBSYSTEM=="net", SYSFS{address}=="00:e0:81:b5:7a:30", NAME="eth1"
>>>>>> # internal 1
>>>>>> SUBSYSTEM=="net", SYSFS{address}=="00:e0:81:b5:7a:31", NAME="eth2"
>>>>>> # internal 2
>>>> Don't touch udev, expecting admins to write udev rules for network
>>>> interface binding is just not realistic. Udev rules are meant to be
>>>> static across hardware reconfigurations while ifcfg files are
>>>> meant to
>>>> be modified to suit your current configuration.
>>>> Use HWADDR="00:1b:21:4d:c3:e8" in the ifcfg files along with
>>>> NAME=eth0
>>>> for eth0 and so on.
>>> I read a while ago that udev overrode ifcfg-* settings so I did a
>>> clean install of 5.4 and changed:
>>> ifcfg-eth0 to ifcfg-eth9 (file name)
>>> eth0 to eth9 (inside the file)
>>> the last number of the HWADDR line
>> Do you mean that you changed the HWADDR line so it no longer matched
>> the actual
>> nic mac address?  In that case, you shouldn't expect it to work.
>>> The nic came up as eth0 with the old/original mac address after a
>>> reboot.
>>> So we unfortunately have to write udev rules when we have nic
>>> naming problems...
>> I think the ifcfg-eth? files work when they match the nic mac
>> addresses.  They
>> may have to all match for any of them to work, though.  I've seen
>> some cases
>> where they all get renamed with a .bak extension and new ones are
>> created but I
>> don't know what triggers that.
> Usually a new kernel that forces a regeneration of the hwconf.
> There was a kernel update maybe the move from C4 to C5 which caused
> grief with Dell hardware, where it reversed the order Broadcom devices
> are detected, still does and needs manual swapping around after install.
> -Ross
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> CentOS at centos.org
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NIC ordering is a problem. Some say it is the multi cpu, some say bad
BIOS, some say MAC address ordering is better, some say PCI bus
enumeration is better.  The netdev mailing list has had a long running
discussion on this issue.  The CTO of Dell and members of HP along
with others are / were active participants.  Part of the problem is
that an alias name may not be available to the kernel.

Dell has their own software to bring determinism to NIC ordering.

One of Dell's programmers has proposed changing Anaconda to let you
choose at installation time the NIC naming convention:

We have been having discussions in the netdev list about creating
multiple names for the network interfaces to bring determinism into
the way network interfaces are named in the OSes. In specific, "eth0
in the OS does not always map to the integrated NIC Gb1 as labelled on
the chassis".

http://marc.info/?l=linux-netdev&m=125510301513312&w=2 - (Re: PATCH:
Network Device Naming mechanism and policy)
http://marc.info/?l=linux-netdev&m=125619338904322&w=2 - ([PATCH]
udev: create empty regular files to represent net)

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