Getting MTU
On occasion, it may be desirable to have the application aware of an interface’s Maximum Transmission Unit. The MTU for a particular interface may be acquired by calling NetIF_MTU_Get() with the appropriate arguments.
Setting MTU
Some networks prefer to operate with a non-standard MTU. If this is the case, the application may specify the MTU for a particular interface by calling NetIF_MTU_Set() with the appropriate arguments.
Note: The configured MTU cannot be greater than the largest configured transmit buffer size associated with the specified interfaces’ device minus overhead. Transmit buffer sizes are specified in the device configuration structure for the specified interface. For more information about configuring device buffer sizes, refer to section Network Interface Configuration.