PTN equipment is a kind of optical transmission equipment used in access layer and convergence layer instead of SDH. Its function is to transmit voice service and data service in fixed network and mobile backhaul. Its biggest feature is to make up for the rigid defect of SDH time slot circuit by realizing statistical multiplexing function.

The future transmission network will be PTN+OTN instead of SHD+DWDM.

The extended data PTN supports a variety of two-way point-to-point connection channels based on packet-switched services, has end-to-end networking capabilities suitable for various coarse and fine-grained services, and provides a "flexible" transmission pipeline more suitable for IP services; It has rich protection methods, and can realize carrier-level service protection switching based on 50ms in the case of network failure, and realize transmission-level service protection and recovery.

PTN inherits the operation, management and maintenance mechanism (OAM) of SDH technology, and has a perfect point-to-point OAM system to ensure the network has the ability of protection switching, error detection and channel monitoring. The interconnection with IP/MPLS is completed in various ways, and the core IP services are seamlessly carried; Network management system can control the establishment and setting of connection channels, realize the distinction and guarantee of service QoS, and provide SLA flexibly.

In addition, it can use various underlying transmission channels (such as SDH/ Ethernet /OTN). In a word, it has perfect OAM mechanism, accurate fault location and strict service isolation function, manages and utilizes optical fiber resources to the maximum extent, ensures service security, and can realize automatic resource allocation and high survivability of mesh network after combining with GMPLS.

Baidu encyclopedia -PTN