Similar to JGRP-2780: provide a new UNICAST4 protocol which uses fixed-size buffers. This would obliviate UFC.
Create a new class ReliableUnicast and subclass UNICAST4. These are the changes:

• UNICAST3 remains unchanged
• The base functionality of UNICAST3 is copied to ReliableUnicast
• UNICAST4 extends ReliableUnicast, and provides fixed buffers. No need for UFC.