Quoting Closed question
Edit the file: /etc/quantum/dhcp_agent.ini and set: dnsmasq_config_file=/etc/neutron/dnsmasq-neutron.conf Create and edit file /etc/neutron/dnsmasq-neutron.conf and put this inside: dhcp-option-force=26,1400 Restart DHCP: service neutron-dhcp-agent restart And reboot your instance. Verify that your MTU is 1400
Doesn't work for me on "Two Node (Controller+Compute) Neutron GRE+OVS+Gluster Cluster" on F20 boxes with Havana manually installed via native repos. Have to run
ifconfig eth0 mtu 1400 up via /etc/rc.d/rc.local to set the MTU to 1400.