10.3. Basic principles

Each shaper tracks how far ahead the link has got with traffic that has been recently sent. This depends on the length of packets sent and the speed of the shaper. This is, essentially, tracking how much is likely to be queued at a bottleneck further on. The FB2500 does not delay sending packets and assumes something with a lower speed is probably queuing them up later.

This record of how far ahead the traffic is gets used in two ways: