Why the recent interest in QoS?
No longer enough for an ISP to keep traffic flowing, links up, routing stable --- offer QoS to be more competitive
QoS is becoming more cost-effective with improved implementation of differentiation tools (classification, queue-manipulation, …), more reliable tools for measuring delivered QoS
Hard to dimension the network as it is becoming increasingly hard (if not impossible) to predict traffic patterns (e.g., 80 local/20 remote rule no longer reliable, now mostly reversed 25/75)
If you throw more bandwidth, there will be more demand (a “vicious cycle”)