While bandwidth guarantees can be implemented by policies within forwarding devices (routers, switches), most installations use a priority scheme instead (or in combination with bandwidth control). Bandwidth guarantees use reservations which are not as efficient as prioritizing by packet.
For Ethernet (layer 2), IEEE 802.1Q provides priority code points in ...
The burden falls upon the TCP PEP to recover any data which is dropped
after the PEP [locally] acknowledges it
Enhancing TCP Over Satellite Channels using Standard Mechanisms
This is a an RFC indicated as "Best Current Practice". All controls recommended for use ...
Pre-ACKing is only possible because the near accelerator keeps the segment data in queue. Therefore, it can ACK in stead of the far destination, prompting the sender to advance the send window and send out more segments than would be possible by delay-bandwidth alone.
Of course, the near accelerator needs to keep track of its internal, larger send window ...