An experimental ARMweb firmware is posted in the files section.
UDPOUT sends an ARP to get the MAC address of the destination. This was
originally done for each UDPOUT, which is a lot of overhead.
Now it sends out an initial ARP, but will continue to use that MAC address as
long as the destination IP in the UDPOUT is the same as the last, and the last
UDPOUT was within the last minute of operation.