When the NorthStar installation script is run in NorthStar releases 4.2.1 and earlier, it complains that the external0 and mgmt0 bridge interfaces have not been configured even though these interfaces are configured.

This article summarizes the problem, and provides a solution.

While installing NorthStar releases 4.2.1 and earlier in a single VM setup (installing NorthStar + JunosVM on the same server), the installation script complains that the external0 bridge interface has not been configured as shown below:

Step 2: Verifying if external0 and mgmt0 bridge interfaces have been configured .....
-------------------------------------------------------------------------------------
./install.sh: line 159: ifconfig: command not found
bridge: external0 is not configured. Please configure external0 bridge before continue.

To verify that the bridge interface is configured, use the brctl show command as shown:

[root@host northstar_bundle_4.2.1]# brctl show
bridge name     bridge id               STP enabled     interfaces
external0       8000.3cfdfec20788       no              ens2f0
mgmt0           8000.ac1f6b49b0da       no              eno1

The installation script for NorthStar software releases 4.2.1 and earlier checks for external0 and mgmt0 bridge interfaces by using the ifconfig command.

However, in CentOS 7 or later releases, the minimal installation method does not include the net-tools package, which includes the ifconfig command. This is the reason for the error message to be reported in NorthStar software releases 4.2.1 and earlier even though the bridges are configured.

A snippet from /opt/northstar/northstar_bundle_x.x.x/install.sh is as follows:

ifconfig external0 2>&1 > /dev/null
  ret=$?
  if [ $ret -ne 0 ]; then
      echo "bridge: external0 is not configured. Please configure external0 bridge before continue."
      echo

ifconfig mgmt0 2>&1 > /dev/null
  ret=$?
  if [ $ret -ne 0 ]; then
      echo "bridge: mgmt0 is not configured. Please configure mgmt0 bridge before continue."
      echo

To resolve the issue, install the net-tools package, which includes the ifconfig command.

yum install net-tools

Meanwhile, the installation script for NorthStar release 4.3 and later has been modified to verify the external0 and mgmt0 bridge interfaces by using the ip link command.

A snippet from /opt/northstar/northstar_bundle_4.3.0/install.sh is as follows:

ip link | grep external0 2>&1 > /dev/null
   ret=$?
   if [ $ret -ne 0 ]; then
       echo "bridge: external0 is not configured. Please configure external0 bridge before continue." << Message will not be seen when bridge exists. 
       echo
ip link | grep mgmt0 2>&1 > /dev/null
   ret=$?
   if [ $ret -ne 0 ]; then
       echo "bridge: mgmt0 is not configured. Please configure mgmt0 bridge before continue." << Message will not be seen when bridge exists. 
       echo