This describes how to check and configure the MTU size
After overcloud deployment is done, it is possible to change the MTU size to a smaller
value than the initial value.
Note: For existing deployments, it is not possible to set the
MTU size to a larger value than the initial value. Overcloud must be redeployed after
making changes in the configuration file if a larger value is desired.
See the
following command examples to check the MTU size and reconfigure after deployment.To check MTU of the Openstack network, run the following command on the director
node.
openstack network show <network> | grep -i mtuFor example:
openstack network show net1 | grep -i mtuAn output example:
| mtu | 8950 |To reconfigure the MTU size, run:
openstack network net1 set --mtu=1500To check the MTU size of a dpdk port, run the following command on the compute nodes.
ovs-vsctl list interface <port> | grep -i mtuFor example:
ovs-vsctl list interface dpdk0 | grep -i mtuAn output example:
mtu : 9000 mtu_request : 9000 ...To reconfigure the MTU size, run:
ovs-vsctl set interface dpdk0 mtu=1500 ovs-vsctl set interface dpdk0 mtu_request=1500To check MTU of a VM instance, run the following command inside the VM.
ip a | grep -i mtuAn output example:
... 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 8950 qdisc fq_codel state UP group default qlen 1000