Instance Unreachable After Attaching Second Neutron Port

Problem

After attaching a second Neutron port to an existing instance, the instance becomes unreachable.

Environment

• Platform9 Managed OpenStack - All versions
• Neutron
• CentOS

Cause

If the second Neutron network you attached to your OpenStack instance has a default gateway, it will override the instances’ existing default gateway.

Resolution

1. Run the following command to use the gateway device from the first Neutron port.

# echo 'GATEWAYDEV=eth0' >> /etc/sysconfig/network

2. Restart the instance if the network connectivity is not restored.