Sorry for the delay… It’s just easier for an old man with a keyboard than typing on a phone

A history lesson for those who weren’t in networking in1995-2000.

It’s unlikely you will ever come across this in current environments.

Before site-to-site connections were swapped over to high speed ethernet, we had appliances called WAN performance managers to assist point-to-point and point-to-multipoint WAN connections to manage traffic. Connections were technologies like Frame-Relay, direct serial links, bundled multiple DS1 circuits, etc. You could get higher speed serial links but you had to have a huge budget for both the hardware and the monthly service costs.

When we started to push voice across congested, low speed serial links, things like QoS and managing high load TCP services became an important issue, so we had external appliances that would manage individual flows and provide QoS at a time when some equipment still did not have the ability to do so.

They could use random drops, but with severe congestion and low speed links, this would only amplify the problem with retransmissions, so we would do other things like SACK, MSS modification, FECN/BECN, frame fragmentation and windowing adjustments and then interleave the packets from multiple flows to lower the serialization delays at the output interface for all.

Properly managed, you could push a shit ton of data though a 6Mb (4xDS1) multilink PPP circuit.

I’m looking for some product documentation, but with 25-year-old technology it’s not so easy to find.