Realization Of TDM Over T-MPLS/MPLS-TP

With the rapid development of telecommunication business, optical transmission technology is also evolving and upgrading. Since 2000, MSTP has been advancing by leaps and bounds driven by the IP business and gradually replaced the SDH which was developed at first. However, the MSTP equipments, which only add a few data services interfaces, are still the circuit-switched essentially just like the SDH equipments. In recent years, as the continually development of the fixed-line data and 3G services, there are a lot of requirement of IP-based transmission network inevitably in order to achieve efficient packet delivery by packet-switched. As an integrated transport network technology with packet and transmission properties, the PTN technology not only can achieve packet switching, high reliability, multi-service or high QoS, but also be able to provide the end-to-end channel management and OAM, transmission line protection switching, the synchronization and timing of network platform, and which is more importantly, the lowest cost per bit transmitted. PTN will replace the MSTP to become the mainstream technology.The mainstream realization technology of PTN is T-MPLS/MPLS-TP and PBT/PBB-TE, the current situation of market shows that the former is paid more attention to because of its advantage of innative compatibility with IP/MPLS core network. On the other hand, there is a long time of co-exist between the traditional TDM and IP data services during the evolution of the network, and there is still a large number of TDM business requirements need to be met. However, TDM services will be damaged and brought difficulties into service clock recovery when through the packet-based network. Therefore, this paper focus on TDM over MPLS-TP, especially the clock recovery problem caused by packet-based network.This paper introduces the development of T-MPLS/MPLS-TP and elaborated on the inheritance to MPLS as well as architecture, key technology and basic principles. After a technical description of the method of TDM over MPLS-TP, turns to the key issues of TDM clock recovery and analyses the impairments in packet-based network. This article proposes an improved method of adaptive clock recovery and realizes the clock recovery module by FPGA, then elaborates the algorithm and principle of its sub-module as well as simulation. At last, the experiment results verify the analysis in preamble which has enlightening meaning.