Optical Transport Network For The Virtual Private Network Traffic Grooming And Multicast Protection Method

More convenient and economical networks are required to support the more popular co-operation between enterprises. The success of the virtual private network (VPN) technology can satisfy the dual need of high flexibility and cost-effective for the VPN users. It is a very important topic on achieving the optimal usage of resources to accommodate multi-service VPN in the same optical transport network environment.Various optical technologies, such as optical cross-connect (OXC) and optical add/drop multiplexer (OADM), and wavelength division multiplexing (WDM) , provide core technologies of next generation intelligent optical network (ION).Within ION,each wavelenth can be operated at very high speed, however, in operational networks, there is a huge bandwidth gap between the capacity of a wavelength and the bandwidth required by low-rate VPN traffic streams. To accommodate such kind of low-rate VPN traffic streams using one lightpath will lead to inefficient resource utilization. At the same time, it is impossible to establish end-to-end lightpaths for all the connection requests of VPN, due to the limits of the number of wavelengths per fiber and the number of transceivers per node. So it is necessary to investigate more efficiently methods to set up connections for these traffic streams. Traffic grooming, which can accommodate low-speed connections into one lightpath, can solve this problem. Additionally, along with the applications of streaming media, video conferences and distributed computing, multicast will obtain the popularization in the optical network. It is particularly important and urgent to provide survivability guaranteed multicast communication comparing to point-to-point communication. This thesis has done some researchs in this area.First, we have investigated the static traffic grooming on VPN. We have analyzed the existing static traffic grooming algorithm, plane construct algorithm, and pointed out its shortcomings. And then we have proposed a new static traffic grooming algorithm called the modified PCA (MPCA). In MPCA, we have defined integrated graph. We put the rest wavelength links and the lightpaths on the same plane. For the case of the connection request can't be set up in the first two steps, we can groom it on the integrated graph. Simulations verified that the performance of the MPCA is better than that of PCA.Second, we have researched the dynamic traffic grooming on VPN. We investigaed the auxiliary graph model and a dynamic traffic grooming algorithm, called holding-time-aware algorithm (HTA). Then we proposed a new algorithm, i.e., modified HTA (MHTA). In light of the lightpath selection, MHTA takes into account the remaining capacity of the lightpath to route a new bandwidth request. And MHTA also try to avoid detour when setting up a request. Seen from the simulation results, MHTA has lower blocking probability than HTA.Third, we have researched the multicast protection problem for the survivability of the network to meet the VPN's high demand on the reliability and time delay. We proposed a new protection method of multicast tree in VPN by providing protection within sub-tree. The innovation of this method is that we have calculated the minimum price path of any two nodes of the multicast tree at the beginning and stored these information. When a link fails, we try to find one minimum price path between the two sub-trees divided by the link to recovery. By doing this, we can save the recovery time and optimize the network resources.