Resource Optimization-Based Research On Key Problems Of Survivability Technologies In Packet Transport Networks

With the rapid development of Internet technology, and the explosive growth of broadband data sevices, transfer of Service on Transport Network has happened from TDM to IP. Tranditional SDH transport network which is mainly for TDM cann't meet the requirement of IP service's transport. Then an intelligent transport layer is needed to pad the huge capacity of fiber with kinds of service efficiently and flexibly, and the transport layer should guarantee the reliability, manageability and expandability of service.Appearance of PTN (Packet Transport Network) transport layer meets the requirements above, and it made the smooth evolution from TDM to IP become possible. Packet Transport Network (PTN) can automatically establish dynamic traffic connections and effectively configure network resources. And also multiple schmes for rapid restoration are provided in PTN. These incredible network functions are realized due to control plane based on GMPLS. Survivability is the key technology which greatly impacts the performance of optical networks. It is used to switch the service interrupted to backup resource when fault happenes to reduce the loss of service. There are two mainly factors in survivability technology, one is protection time, and the other is protection resource. The survivability problems are investigated in depth in the above two aspects in this paper with the support of the High-Tech Research and Development Program of China. The main innovative contributions about survivability based on resource optimization are listed as follows.Firstly, According to the T-MPLS standards and theory, network architecture of Packet Transport Network (PTN) based on T-MPLS and the function of nodes are designed, including control unit, management unit and switching and forwarding unit. Adaptation and carrier of multi-service in node interfaces are researched to realize the access of multi-service. OAM function is implemented to manage and control the network and finish the functions of ring protection.Secondly, Equal cost multi path technology (ECMP) can realize load balance, but it will bring the problems of management in PTN. In the paper the carrier-grade management is considered, and OAM functions in ECMP domain are researched. OAM frames are expanded and sub-path identification is added, then the function in the source and end nodes of ECMP domain is modified, to finish end to end OAM function in the domain including ECMP.Thirdly, based on previous study, shared-bandwidth reservation and backup path establishment strategy is proposed to solve the problem of large resource consumption in fast reroute. RSVP protocol has been expanded to realize bandwidth sharing among backup paths of different service LSPs during the establishment of backup path. A routing algorithm for backup path computation and its enhancement are proposed to solve out the problem of sharing among backup paths that belong to different SRLG work paths.Fourthly, based on survivability of multicast, two aspects are researched according to the feature of multicast tree. On the one hand, protection time is considered. A restoration technology of finding backup path is proposed to reduce the protection time and speed up the protection. On the other hand, protection resource is considered. A fast reroute protection strategy of avoiding path repeat and loop is rased to implement resource optimization.