Implementing fair bandwidth allocation schemes in hose-modelled VPN

The virtual private network (VPN) provides customers with predictable and secure network connections over a shared network infrastructure. The recently proposed hose model for VPNs has desirable properties in terms of greater flexibility and better multiplexing gain. However, the 'classic' fair bandwidth allocation scheme introduces the issue of low overall utilisation in this model; furthermore, when the VPN links are established, the VPN customers cannot manage their VPN resources by themselves dynamically. The authors propose a fluid hose-modelled VPN, and based on this model they develop an idealised fluid fair bandwidth allocation scheme to improve the performance of the VPN. With the proposed scheme, they achieve two goals: maximising the overall throughput of the VPN; and providing a mechanism that enables the VPN customers to allocate the bandwidth according to their own requirements, thus achieving the predictable QoS performance. Based on deficit round robin (DRR), a transmission scheduling scheme for output buffer switches, a novel scheme, two-dimensional deficit round robin (2-D DRR), is developed to approximate/realise the idealised fluid fair bandwidth allocation scheme for the hose-modelled VPN. The simulation results also show that the 2-D DRR can improve the overall throughput without compromising fairness and implementation complexity.