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Old 09-21-2015, 02:58 PM   #1
jake_kugel
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Interface names assigned to different physical NIC cards after reboot


Hello,

we are using RedHat Enterprise Linux 7, and we are using an application that requires us to rename the network interface names from what they are given by biosdevname to ensure same name used across multiple RHEL servers, for example management NIC always eth0, data NIC always eth1, etc. We have disabled the new biosdevname support and we do see interface names eth0, eth1, eth2, ... ethn being assigned.

The step we are having trouble with is assigning specific physical NIC cards specific eth* names. We have tried using the HWADDR property in the ifcfg-* file, following a tip from this site:

http://keithtenzer.com/2014/12/12/re...ces-in-rhel-7/

For example from /etc/sysconfig/network-scripts/ifcfg-eth0:

HWADDR=6c:ae:8b:27:64:32

However after a reboot, the interface names are being assigned to different physical NIC cards. As an alternative, we have also tried creating the file /etc/udev/rules.d/70-persistent-net.rules, following this web page:

https://alteeve.ca/w/Changing_Ethern...d_Fedora_15%2B

For example:

SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="6c:ae:8b:27:64:32", NAME="eth0"

And interface names still assigned to different NIC cards. At this point I'm not exactly sure what to check next, does anyone have any ideas of how we could debug?

Thanks,
Jake
 
Old 09-21-2015, 04:46 PM   #2
jefro
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Hello and welcome to LQ.

The best place to start is with your service contract for assistance with RH. Second to that would be the documentation at RH.

https://access.redhat.com/documentat...ce_Naming.html

"Scheme 5: The traditional unpredictable kernel naming scheme, is used if all other methods fail (example: eth0)."

This is one of the reasons that RH and other are adopting the BDS style naming.

RH even being cloned to a similar system can mess up that naming.

Guess you could try some other attempts if the link doesn't help.

Last edited by jefro; 09-22-2015 at 07:26 PM.
 
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Old 09-24-2015, 12:50 PM   #3
jake_kugel
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Okay, thank you for your reply. Definitely, I will try RHEL technical support, and will read RHEL documentation again. If I do find the cause, I'll post back here with it.

Thanks again,
Jake
 
Old 09-24-2015, 09:45 PM   #4
jefro
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I have seen it fail even on clones to similar systems. I quoted the last line of RH's doc's to point out their opinion of "unpredictable kernel naming scheme"

If you do find a good solution we would welcome your method and appreciate you telling it.
 
Old 09-28-2015, 01:20 PM   #5
jake_kugel
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Thanks for the pointer to the RHEL documentation, I believe we might have found an answer there. Before this we were trying to assign eth* names to specific NICs, such as eth0, eth1, eth2, etc. This RHEL page though says if we assign custom names we should assign something other than eth* names, see Example 8.3 at the bottom of this page:

https://access.redhat.com/documentat...ce_Naming.html

After reading this we switched to mgmt0, mgmt1, data0, data1, etc for our custom names. So far, this appears to be working -- we've rebooted about 6 times without problems. I still have some doubt whether this will always work 100% correctly, but we are going to test this approach for a period of time and see if it continues to hold.
 
Old 09-28-2015, 02:59 PM   #6
jefro
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Thanks for the update and tip.



"Use of interface names from kernel namespace is discouraged. To get predictable and stable interface names please use some other prefix than "eth". "

https://access.redhat.com/documentat...ce_Naming.html

There you go.

Last edited by jefro; 09-28-2015 at 03:02 PM.
 
  


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