Consistent Network Interface Naming

For RHEL 7 the network interface names have changed from the legacy ethX style to a modern consistent naming scheme.

The details are described in the Dell Consistent Network Device Naming in Linux document. The Redhat networking guide also has a very useful chapter - Consistent Network Device Naming.

Here are the details for supported models.

Model	Name	`ID_NET_NAME_ONBOARD`	`ID_NET_NAME_PATH`	SMBIOS
Dell Optiplex 745	enp2s0		enp2s0	2.3
Dell Optiplex 755	enp0s25		enp0s25	2.5
Dell Optiplex 780	enp0s25		enp0s25	2.5
Dell Optiplex 790	em1	eno1	enp0s25	2.6
Dell T5610	?		enp0s25	2.7
HP DC7900	enp0s25		enp0s25	2.5
HP 8000 Elite	enp0s25		enp0s25	2.6
HP 8200 Elite	em1	eno1	enp0s25	2.7
HP 8300 Elite	em1	eno1	enp0s25	2.7
HP 800 EliteDesk G1	em1	eno1	enp0s25	2.7
HP 800 EliteDesk G2	em1	eno1	enp0s31f6	2.7
HP Z220	em1	eno1	enp0s25	2.7
Dell PowerEdge 1950	enoX	eno1 / eno2	enp3s0 / enp7s0	2.5
Dell PowerEdge R200	enoX	eno1 / eno2	enp3s0 / enp4s0	2.5
Dell PowerEdge R220	emX	eno1 / eno2	enp2s0f0 / enp2s0f1	2.7
Dell PowerEdge R310	emX	enoX	enp2s0fY	2.6
Dell PowerEdge R330	emX	eno1 / eno2	enp4s0f0 / enp4s0f1	2.8
Dell PowerEdge R420	emX	eno1 / eno2	enp2s0f0 / enp2s0f1	2.7
Dell PowerEdge R430	emX	enoX	enp2s0fY	2.8
Dell PowerEdge R510	emX	enoX	enp1s0f0 / enp1s0f1	2.6
Dell PowerEdge R520	emX	enoX	enp2s0fY	2.7
Dell PowerEdge R710	emX	enoX	enp1s0fY / enp2s0fY	2.6
HP DL180 G6	emX		enp8s0fY	2.6

SMBIOS Version

For older versions of the SMBIOS the name will be the ID_NET_NAME_PATH, with newer versions it will be based on ID_NET_NAME_ONBOARD. On Dell it appears that the cut-off version is 2.6, on HP it appears to be 2.7.

To find the SMBIOS version use the following commands:

/sbin/dmidecode -t 41 | grep SMBIOS
/sbin/dmidecode -t  9 | grep SMBIOS
/sbin/biosdecode | grep SMBIOS

Finding network names

To find the network interface names use the udevadm tool, something like this:

udevadm info -e | grep ID_NET_NAME

This blog article was very helpful for working out how to discover the various information.

If a machine is still using the legacy name (e.g. eth0) then the biosdevname tool can be used to find out what it would return.

/sbin/biosdevname --smbios 2.6 --nopirq --policy physical -i eth0

This is the command used in /usr/lib/udev/rules.d/71-biosdevname.rules, if this returns anything that is the interface name to use, if nothing is returned then it seems that the ID_NET_NAME_PATH name will be used instead.

-- Main.ascobie - 2016-02-16

Topic revision: r11 - 2016-12-09 - squinney

LCFG: Large Scale Unix Configuration System

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