Architecture and Analysis for Providing Virtual Private Networks (VPN) with QoS over Optical WDM Networks

In this paper, we study the problem of employing virtual priv ate networks (VPN) over wavelength division multiplexing (WDM) networks to satisfy diverse qu ality of service (QoS) requirements of different VPNs. A wavelength routed backbone network is consid ere . A VPN is specified by the desired logical topology and ana priori traffic matrix. The network provides three type of paths over which sessions are established: (i) Dedicatedlightpath (DLP) – an all-optical path spanning intermediat e optical cross connects, which is used by exactly one VPN; (ii) Sharedlightpath (SLP) – an all-optical path shared by multiple VPNs. Access nodes (where E/O conversion takes place) at the border of the optical backbone provide the necessary electronic buffering when c ontention arises due to shared lightpaths; and (iii) Multi-hop path(MHP) – a hybrid path composed of a tandem of optical lightpat hs with O/E and E/O conversion at the junction between the two lightpaths. Depe nding on the QoS requirements of the VPN, one or more of these lightpath types are used to carry the VPN’ s traffic. Three traffic types are defined – Type 1carried over DLPs as far as possible; Type 2carried over SLPs; and Type 3carried over MHPs. A VPN’s traffic matrix will specify information on each of the t hree different types. The network will then try to accommodate the given requirements, maximizing the t he network utilization. In this paper, we present a simulation based analysis of the system performan ce for different system configurations, e.g. different number of wavelengths on physical links, differe nt number of VPNs that share one lightpath, etc.