When implementing jumbo frames for storage it is important to verify what the actual Maximum Transmission Unit (MTU) is for the path between your host and storage unit. The steps included in this document will return a quantitative
 value unique to the given environment.

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Instructions

Note: The ping utility adds some additional bytes to the packet 28 to be exact so that is taken into consideration when performing the following tests.

1.  Identify the IP addresses of the SAN/NAS target being attached.
2. From the XenServer CLI perform the following command:

If the command succeeds with replies from the target the MTU value of 9000 is supported in this environment.

If the command returns a message stating that "Frag is needed and DF set" then the environment does not support the MTU value of 9000.

3. If the command failed adjust the value set for  -s to a lower number incrementally until the ping succeeds.
4. The value where the ping succeeds + 28 is the supported MTU for the given environment.