I'm wondering about this too; assumed it was data compression or some way to achieve an effective 16Gbps while the physical link is still 10Gbps. Looking forward to the answer.
We enabled a system MTU of 13312 with the hopes that the increase would correct a problem with input errors which incremented at the exact same rate as the jumbo frame count. The change did not affect the input errors.
No further clarification from Support. They have been able to replicate it but they have no answers yet. They are working with the engineers. This ticket has been closed so I don't know that I will be informed of any further progress.
When you get a chance, if you would like to send me a personal message with the ADTRAN ticket number, I will be happy to review it for you. Also, do not hesitate to ask any additional questions or provide information to this post.
Input errors on stacking ports has been resolved in R11.10.5 firmware. These were false counts of packets that were supposed to be dropped but were still counted as input errors.
Just noticed this post and thought I would update it.