More on RED
RED is a congestion avoidance mechanism (rather than congestion control), i.e. it predicts when congestion is about to happen, and reduce the rate at which hosts send data just before queue saturation
Probability of dropping a particular flow’s packet(s) is roughly proportional to the share of the bandwidth that flow is currently getting
Max P is typically set to 0.02
If traffic is bursty, then min threshold should be sufficiently large to allow link utilization to be maintained at an acceptably high level
Difference between two thresholds should be larger than the typical increase in calculated average queue length in one RTT; setting max threshold to twice min threshold seems reasonable
RED is fair; can’t differentiate services with fairness
Unfair or weighted RED: lower drop probability for higher priority traffic. Priorities set at edge routers or hosts