MTU Configuration

Getting Started with Napatech Link-Virtualization™ Software

Platform
Napatech SmartNIC
Content Type
Getting Started Guide
Capture Software Version
Link-Virtualization™ Software 4.4

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 mtu
For example:
openstack network show net1 | grep -i mtu
An output example:
| mtu                       | 8950                        |
To reconfigure the MTU size, run:
openstack network net1 set --mtu=1500
To check the MTU size of a dpdk port, run the following command on the compute nodes.
ovs-vsctl list interface <port> | grep -i mtu
For example:
ovs-vsctl list interface dpdk0 | grep -i mtu
An 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=1500
To check MTU of a VM instance, run the following command inside the VM.
ip a | grep -i mtu
An output example:
...
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 8950 qdisc fq_codel state UP group default qlen 1000