Framework for dynamic optical virtual private networks (VPNs): architecture and analysis

The authors explore the problem of dynamic virtual private networks (VPNs) over wavelength division multiplexing (WDM) networks to facilitate the guarantee of diverse quality of service (QoS) requirements of different traffic streams, especially those with very stringent delay jitter requirements and with bursty characteristics. Each VPN consists of different traffic streams with various quality sensitivities. The proposed QoS model provides three types of 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 a constant bit rate (CBR). The OBS type need to setup the lightpath using so-called optical burst switching while a traffic stream with variable bit rate (VBR) request, is occurring. The alternative type has to set up 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 sensitivities to delay and jitter. By employing dynamic VPNs directly over the WDM layer, one can eliminate the often complex QoS related functions in the upper protocol layers, and thus increase the overall communication efficiency. Furthermore, this could be the first step towards providing fine grained service over optical wide area networks. In addition, basic performance analysis and preliminary results are presented, based on simulation, and the network designer is provided with a quantitative assessment of proportion for different traffic types with different QoS service requirements.