Fair Bandwidth Sharing Among Virtual Networks: A Capacity Resizing Approach

Virtual Private Networks (VPN) and link sharing are cost effective way of realizing corporate intranets. Corporate intranets will increasingly have to provide Integrated Services for voice and multimedia traffic. Although packet scheduling algorithms can be used to implement Integrated Services in link sharing [1] and virtual private networks [2], their statistical multiplexing gains are limited. Recently capacity resizing of Virtual Leased Links (VLLs) has been proposed to obtain better statistical multiplexing gains. Carrying out capacity resizing naively may result into unfair distribution of capacities among different VPNs. This is a serious problem especially because the VPN customers who pay for the service expect a well defined grade of service and protection from other misbehaving customers sharing the same infrastructure. We propose a new scheme called Stochastic Fair Sharing (SFS) to carry out fair link sharing and fair sharing among VLLs. In the link sharing environment, capacities allocated to different classes are adjusted dynamically as sessions arrive (or depart). The SFS admission control algorithm decides which sessions to accept and which to reject depending upon the current utilizations and provisioned capacities of the classes. SFS gives protection to classes with low session arrival rate against classes with high session arrival rates by ensuring them a low blocking probability. In case of multi-hop VLLs, capacity resizing requests are sent in the service proviers’s network which are admission controlled using SFS. Our simulations indicate that using SFS, equivalent capacity of virtual links converge to their max-min fair capacity, with a fairness index of 0:97 in extreme situations. The average signaling load of the protocol was found to be reasonable. The scheme is simple to implement, efficient, and robust. The potential applications of SFS are fair and efficient resource sharing in telecommunication networks, ATM networks, virtual private networks (VPN) and integrated services or differentiated services based IP networks.