A design for on-line virtual private networks (VPN) over optical WDM networks

Abstract

We explore the problem of designing on-line virtual private networks (VPN) over wavelength division multiplexing networks (WDM) to facilitate the guarantee of diverse quality of service (QoS) requirements of different traffic streams especially that with very stringent delay jitter requirement and that with bursty characteristic. Each VPN consists of different traffic streams with various quality sensitivity. The proposed QoS model provides three types QoS services for various VPNs, static, optical burst switching (OBS) and alternative VPNs. All the three types provide transmission in the optical core networks without any O/E/O conversion. The static type has a set of dedicated or shared lightpaths which have been pre-allocated and the traffic from this VPN has constant bit rate (CBR). The OBS type need to setup the lightpath using a so called optical burst switching (OBS) while a traffic stream with variable bit rate (VBR) request is occurring. The alternative one has to setup a lightpath based on two-way reservation protocols such as tell-and-wait (TAW) for the traffic with unspecified bit rate (UBR) or available bit rate (ABR). The proposed model is suitable for carrying the multimedia applications which have various sensitivity of delay and jitter. By employing dynamic VPNs directly over WDM layer, we can eliminate the often complex QoS related functions in the upper protocol layers, thus increase the overall communication efficiency. Furthermore, this could be the first step toward providing fine grained service over optical wide-area networks. In addition, we present preliminary results based on simulation and provide a network designer with a quantitative assessment of proportion for different traffic types with different QoS service requirements.