Provisioning QoS enabled VPN services over packet switched networks is increasingly important for service provider. Some prior works adopted a proactive service setup approach such as the measurement based service admission control, but little attention has been given to control the congestion and maintain QoS after the service has been instantiated. Congestion control is a key issue for network service provider to manage QoS assured VPN services. Most studies in congestion control have focused on buffer management and tried to maintain the queue length to a preset value. This paper proposes a rate-based feedback control system that maintains preset packet loss targets for instantiated VPN services in the provider's backbone network. Specifically, the system utilizes the estimation for packet loss probability as the feedback signal, and then applies a PI controller to throttle ingress customers' traffic rates. Through a number of simulation experiments, the transient and steady state performance of the controller is evaluated. The numeric results show that the control system is effective in maintaining the network operation within a prescribed loss range.
['Dongli Zhang', 'Dan Ionescu']
Feedback control of packet loss for VPN services