I noticed all SDK examples don't use checksum offloading for IP, TCP, UDP and ICMP, but the hardware is capable to do this.
There's a macro in lwipopts.h named CHECKSUM_BY_HARDWARE, but it is undefined. Anyway, defining it doesn't work, because I think the driver fsl_enet.c must be changed to activate and use checksum offloading.
Could NXP provide a full example with checksum offloading enabled?