Models and algorithms of data flows switching efficiency improving in all-optical telecommunications systems

Автори: 
O.V. Koretskyy, S.S. Dumych

Lviv Polytechnic National University

Modern optical networks still in development to AON (All-Optical Networks). The main goal of all related works is providing the state-of-the-art optical switching techniques, designing of new solutions and applications.  The first stage in this development was circuit-switched optical networks. In those types of networks the incoming request would dropped in case of channel blocking.  Another case – packed-switched optical networks. In those networks, the data flows divided onto many independent packets. Nowadays, this technique is the most famous. The main advantage of this technique is possibilities of queues. In case of channel blocking, the packet stills in buffer, until it will sent or dropped. The next generation of optical switching is Optical Burst Switching technology. Optical burst switching (OBS) is a promising solution for all-optical wavelength-division multiplexing (WDM) networks. It offers to some extent the flexibility and efficient bandwidth usage of optical packet switching networks, while taking into account the limitations of the current all-optical technology. For this reason, it could seen as an intermediate technique between all-optical wavelength routing networks and optical packet switching networks. The OBS technology allows satisfying requirements of IPoDWDM conceptions, because of full compatibility with IP/Ethernet networks. The ingress edge node assembles incoming packets from the client terminals into bursts. The assembled bursts transmitted all-optically over OBS core routers, without any storage at intermediate nodes within the core. The signaling scheme in an optical burst-switched network is typically implemented using out-of-band burst header packets. In an out-of-band signaling scheme, the header associated with a burst transmitting on a different wavelength from the burst itself. The out-of-band header packet travels along the same route as the burst, informing each node along the route to configure its optical cross connect to open the necessary virtual channel for transmitting the burst with variable size. The mathematical model of the core node in the network with switching units, which describes the sequence of signaling packet processing, proposed in this paper. This model based on the matrix calculation, and able to implement on field programmable gate arrays. Furthermore, the model of IP-packet aggregation in the ingress node network that takes into account probability distribution of IP-traffic proposed. Simulation results determined that proposed algorithm 10 times reduces the IP-packet losses, providing the same bandwidth. We provide the simulation of optical burst switching network for different signaling schemes. Our experiment shows that the INI scheme is more flexible, and able to reconfiguration in dependence of traffic requirements. INI is able to combine advantages of both JET and TAW schemes. Using the INI signaling technique allows to increase the efficiency of wavelength routed networks taking into account properties of traffic.