OpenStack: Setup MTU for VM instance's network

 

Within the VM instance, set the network interface MTU to 1400 bytes.

To set the MTU automatically to 1400 by neutron dhcp server, follow below steps. This is achieved by dhcp server sending out 1400 MTU to instances as a dhcp option.

• Create file /etc/neutron/dnsmasq-neutron.conf with below content in it.

dhcp-option-force=26,1400

• Edit /etc/neutron/dhcp_agent.ini and add below.

dnsmasq_config_file=/etc/neutron/dnsmasq-neutron.conf

• Then kill all existing dnsmasq processes and restart dhcp-agent. Or reboot the network node.

# service neutron-dhcp-agent restart