How to ensure predictable network device names with AutoYaST

This document (7006937) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 11 Service Pack 1
SUSE Linux Enterprise Server 11
SUSE Linux Enterprise Desktop 11 Service Pack 1
SUSE Linux Enterprise Desktop 11

Situation

When mass installing SUSE Linux Enterprise (SLE) 11 and newer versions on hardware with similar hardware configuration including more than one network interface card (NIC), the enumeration of eth? devices may be inconsistent across machines. This can be due to minor differences in the hardware like which NIC that answers first etc.
As an example an on-board NIC may be named eth0 in one host, while an extra NIC gets assigned eth0 and the on-board is eth1 in another host.

Resolution

This can create a variety of problems, but can be avoided by defining <net-udev> rules based on the PCI bus IDs of the NICs in the AutoYaST profile that is being used to install the machines.

Follow the steps below to implement the solution.

Determine the PCI IDs of the different NICs in an already installed system. This is the value of "SysFS BusID" for each of the NICS in the output of the command
```
# hwinfo --netcard
```
e.g. 0000:04:01.0
Make sure there is an interface definition for each of the NICs in the <interfaces> section in the AutoYaST profile. E.g. :
     <interface>
       <bootproto>dhcp4</bootproto>
       <device>eth0</device>
       <startmode>auto</startmode>
     </interface>
     <interface>
       <bootproto>dhcp4</bootproto>
       <device>eth1</device>
       <startmode>auto</startmode>
     </interface>
Define a rule for each NIC in a <net-udev> subsection of<networking> like below :
   <net-udev config:type="list">
     <rule>
       <name>eth0</name>
       <rule>ID</rule>
       <value>0000:04:04.0</value>
     </rule>
     <rule>
       <name>eth1</name>
       <rule>ID</rule>
       <value>0000:04:01.0</value>
     </rule>
      ...
   </net-udev>
Install using the profile
After the installation the eth devices should be defined as expected based on rules created in /etc/udev/rules.d/70-persistent-net.rules.
The example above would lead to a rules file with the following content :
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ID=="0000:04:04.0", NAME="eth0"
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ID=="0000:04:01.0", NAME="eth1"

It is of course also possible to base the rules on other sysfs attributes, but detailing that is beyond the scope of this document.

Disclaimer

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