[CentOS] How Do I ...

Thu Apr 15 04:20:45 UTC 2010
Jobst Schmalenbach <jobst at barrett.com.au>

in the olden days it was so easy, you had PCI cards and
they were named by the slot number, starting with eth0 in PCI slot 1 and so on.
Then came the inbuilt nics
Then came the PCIx built nics
Then came the PCI-e built nics

OUCH! ;-)

run ifconfig and get all hardware addresses first AND(!) look at the hardware, its written on them and for inbuilt nics its written on the plug (sometimes you can see it in the bios as well).

If you not sure which hardware address belongs to which you can unplug and plug ONE cable at a time AND "tail -f /var/log/messages" and see what ethX number was unplugged ... write the details of THAT card down (one at a time).

Name the ifcfg-ethX file in /etc/sysconfig/network-scripts/ in order (IMPORTANT), e.g.:

  -rw-r--r--  1 root root   480 Apr 02 23:47 ifcfg-A_eth0
  -rw-r--r--  1 root root   245 Apr 02 23:48 ifcfg-B_eth1
  -rw-r--r--  1 root root   258 Apr 02 23:49 ifcfg-C_eth2
  -rw-r--r--  1 root root   258 Apr 02 23:50 ifcfg-D_eth3

make sure that the names of the config files begin with "ifcfg-" or it will not work.
Then you edit these files and set the hardware addresses and other (ipaddresses etc)
The reason why you do this:

  if for example the nics have the same driver, by naming them in 
  order at boot time there are INITIALIZED IN THAT ORDER.
  This too makes sure that the kernel knows what **you** think is the order.

I have a server that has 5 different nics in it, with 2 PCI, 1 PCI-e, 2 inbuilt.
I have them working correctly every boot, in the same order, correct IP and everything.


On Wed, Apr 14, 2010 at 10:58:36AM -0400, gene.poole at macys.com (gene.poole at macys.com) wrote:
> All,
> I've got a machine running CentOS 5.3 and this machine has got 2 - 
> built-in 1 Gig NICs and a expansion card with 4 - 100 Meg NICs.  For 
> whatever reason at install time, it made the expansion card eth0 through 
> eth3 and the internal ports eth4 and eth5. And by default the 'machine' is 
> known on the network by the eth0 NIC, so my throughput is limited to 100 
> Mb.  How can I force the internal NICs to be eth0 and eth1?
> Thanks,
> Gene Poole

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