Manually checking a permitted MTU ensures a configured MTU is transmitted. The ping command is used to confirm if an MTU can be transmitted. Start with the largest MTU and work down to find the limit.
For example, to check if an MTU of 8900 bytes is transmitted to an endpoint, from the OneFS CLI, use the following command: ping –s 8900 –D <IP Address>. The -s specifies the packet size, and the -D specifies not to fragment the packet.
If the ping is successful, the MTU is transmitted across. If the ping is unsuccessful, gradually lower the MTU until it is successfully transmitted. Verify that the MTU can be transmitted from both endpoints.
OneFS is based on FreeBSD. FreeBSD also has options for gradually increasing the MTU by performing a “sweeping ping” using the –g option. For more information about ping options in FreeBSD, access the FreeBSD manual at the following link: