Study On Some Key Technologies Of The Optical Transport Network (OTN)

With the rapid development of data services, especially the emergency of broadband, IPTV, and VOD services, the traditional transmission networks have to face new challenges. The future of operators is to provide full-service support capabilities, so the transport network of efficient, reliable and flexible high-capacity will promote the development of telecommunication. As the next generation transport technology, OTN has raised more and more concerns.However, there are many important problems havn't be solved in OTN. For example, variable rate packet client signals over OTN, multicast routing in OTN and shared mesh protection of OTN, all of which need to enhance the capabilities of OTN. Thence, it is very important to research those key technologies for OTN. This paper has researched the above-mentioned key technologies and gained some innovative results. The main contributions of this thesis are following:1. To improve the bandwidth utilization of variable rate packet client signals over OTN, this paper proposes a mechanism to accomplish bandwidth adjustment of ODUflex(GFP), which can save considerable bandwidth by verification of simulation. The proposed bandwidth adjustment scheme considers the expandability and the flexibility of application. The simulation results demonstrate that ODUflex with the adjustment capability can save more than 50% bandwidth of ordinary ODUflex when rate variation range of packet service is large. In addition, each link used by ODUflex can save more than 14% of bandwidth.2. Electronic layer multicast of OTN can reduce costs and improve bandwidth utilization, so this paper proposes a load-balancing link-sharing minimum-cost heuristic algorithm for static multicast routing (LPMH) and a load-balancing delay-constrained minimum-cost heuristic algorithm for dynamic multicast routing (LDMDH). LPMH solve the problem of MPH that does not involve sharing of a link bandwidth and load-balancing. LPMH is suitable for the quasi-static network whose architecture and multicast group changes in low frequency. The simulation results of LPMH show that it is able to save 5% of cost than MPH, and its load-balancing degree is 6-8 times of MPH. LDMDH takes account of load balancing under delay-constraint, which is suitable for the network whose architecture and multicast group changes dynamically. The simulation results show that the tree cost of LDMDH is about 5% higher than MPH's but its load-balancing degree is 4 times of MPH.3. The realization of OTN shared mesh protection will save network bandwidth resources, this paper puts forward a priorities-differentiated load-balancing minimum-cost shared path protection algorithm for protection routing (PLMC-SPP) and an APS protocol. PLMC-SPP provides shorter work and protection routings for the services with higher priorty, and considers the load-balancing while it constructs the shared protection path. The simulation results of PLMC-SPP show that its block probability is 27% lower than SPP's, its shared degree of protection resource is 11% higher than SPP's, and its load-balancing degree is 1.9 times of SPP. The work path and protection path of the service with higher priority, which are constructed by PLMC-SPP, are respectively 0.5 hops and 0.8 hops shorter than lower priority. The new APS protocol is designed to promote standardization of shared mesh protection in OTN. The simulation results of such protocol show that it can deal with the problems of multiple fault conditions.