One solution is one ACK spacing box per downlink. When it sees well-interleaved traffic, it doesn't need to do spacing. Tim Shepard pointed out that the queue being overrun is at the bottleneck, memory at the bottleneck would help, and asked how does the box know the bottleneck rate. Van replied that that information is in the ACK spacing unless the ACKs have been compressed by the queue. The signature is a bunch of ACKs close together followed by a big gap.
Research is needed on when the algorithm turns on and off.
Van claimed the kick-in point can be fairly high. Van Jacobson replied that no, these would all be separate connections, but would have to sort out dynamics like 1.1 where you send some data then wait a bit and send some more. Van claimed that routers can easily buffer 32K windows, during that time can find the pattern, doesn't have to trigger too early. Van Jacobson stated that delayed ACKs wrongly implemented are a disaster. He said that the ACK spacing algorithm isn't going to trigger until fairly late in slow start, e.g., after seeing bursts on 15 or so ACKs, the window is open enough so delayed ACKs aren't affecting the number of ACKs in flight.