Interface name changes after update to RHEL 7.3 and network does not start

Root Cause

• This issue is a result of an update in internal development version systemd-219-21.el7 and later to provide persistent device names across reboots caused by incorrect and inconsistent device names reported by the VMware firmware/bios. From the errata:

  "Previously, some network devices had unacceptably long names. This was due to certain firmware reporting meaningless data, such as the device's `onboard index` value, which the kernel passed to user-space. This resulted in problems with maximum name length, especially with VLANs. With this update, *systemd* rejects unacceptably long names and falls back to a different naming scheme. As a result, long network device names will no longer appear."
  

• The slot name of an interface can be seen before the system is updated/restarted so that any interface configurations can be adjusted in advance. Locate the ID_NET_NAME_SLOT property with udevadm. In the example below, the slot-based name for the device eno16780032 is ens192:

  # udevadm info /sys/class/net/eno16780032
  P: /devices/pci0000:00/0000:00:16.0/0000:0b:00.0/net/eno16780032
  E: DEVPATH=/devices/pci0000:00/0000:00:16.0/0000:0b:00.0/net/eno16780032
  E: ID_BUS=pci
  E: ID_MODEL_FROM_DATABASE=VMXNET3 Ethernet Controller
  E: ID_MODEL_ID=0x07b0
  E: ID_NET_DRIVER=vmxnet3
  E: ID_NET_LABEL_ONBOARD=enEthernet0
  E: ID_NET_NAME_MAC=enx005056a570ba
  E: ID_NET_NAME_ONBOARD=eno16780032
  E: ID_NET_NAME_PATH=enp11s0
  E: ID_NET_NAME_SLOT=ens192
  E: ID_OUI_FROM_DATABASE=VMware, Inc.
  E: ID_PATH=pci-0000:0b:00.0
  E: ID_PATH_TAG=pci-0000_0b_00_0
  E: ID_PCI_CLASS_FROM_DATABASE=Network controller
  E: ID_PCI_SUBCLASS_FROM_DATABASE=Ethernet controller
  E: ID_VENDOR_FROM_DATABASE=VMware
  E: ID_VENDOR_ID=0x15ad
  E: IFINDEX=2
  E: INTERFACE=eno16780032
  E: SUBSYSTEM=net
  E: SYSTEMD_ALIAS=/sys/subsystem/net/devices/eno16780032
  E: TAGS=:systemd:
  E: USEC_INITIALIZED=28864
  

• Also be aware that any application or configuration which specifically refers to the old interface name will need to be updated to refer to the new interface name. Please contact the appropriate application vendor for any questions regarding this point.

• The updated systemd-219-30.el7_3.6 package includes the following RPM %POST script which locates any problematic enoX style interface names and creates a persistent udev rule so their names will not unexpectedly change upon reboot:

  %triggerin -- systemd < 219-21
  . /etc/sysconfig/network-scripts/network-functions
  
  RULES_FILE="/etc/udev/rules.d/90-eno-fix.rules"
  DRACUT_CONFIG="/etc/dracut.conf.d/90-eno-fix.conf"
  
  NEED_REBUILD=
  WROTE_MSG=
  
  for i in /sys/class/net/eno* ; do
      DEVICE=${i##*/}
  
      [[ "$DEVICE" =~ eno[0-9]+(d[0-9]+)?$ ]] || continue
      [ "$(echo $DEVICE | sed -e 's/eno\([0-9]\+\).*/\1/')" -lt "16383" ] && continue
  
      HWADDR=$(get_hwaddr $DEVICE | tr '[:upper:]' '[:lower:]')
      [ -z "$HWADDR" ] && continue
  
      if [ -z "$WROTE_MSG" ]; then
         echo "# This file was automatically generated on systemd update" > "$RULES_FILE"
         WROTE_MSG=yes
      fi
  
      echo "SUBSYSTEM==\"net\", ACTION==\"add\", DRIVERS==\"?*\", ATTR{address}==\"$HWADDR\", NAME=\"$DEVICE\"" >> "$RULES_FILE"
      NEED_REBUILD=yes
  done
  
  if [ -n "$NEED_REBUILD" ]; then
      echo "install_items+=\" $RULES_FILE \"" > "$DRACUT_CONFIG"
      dracut -f
  fi
  

Related links:
- https://www.redhat.com/en/about/blog/red-hat-enterprise-linux-73-achieving-persistent-and-consistent-network-interface-naming-vmware-environments
- https://bugzilla.redhat.com/show_bug.cgi?id=1391944
- https://communities.vmware.com/thread/478439?start=0&tstart=0
- https://github.com/systemd/systemd/commit/6c1e69f9456d022f14dd00737126cfa4d9cca10c