1. Equipment Interoperability Issues
PTN and OTN are the emerging technology of DWDM, OTN inherited the bulk transfer function at the same time, the introduction of flexible scheduling based on the wavelength, sub-wavelength features, its greatest feature is the use of a fully open system architecture, its hosted business the relationship between the client layer and the service layer, can be said to be innate transparent transmission platform. For OTN+PTN joint networking is no exception, OTN as a transparent delivery platform for convergence layer and access the service layer and the client layer, independent of each other, very similar in the mass deployment of WDM and SDH network relationships. OTN carrying the PTN, like WDM carrying SDH.
2. Precise time synchronization problem
Time synchronization is a new demand for 3G mobile standard, especially in terms of China's three major carriers, not an accurate time synchronization network, in the construction of transmission network, with particular attention to the precise time synchronization problems. In view of the technical system from terrestrial transmission time synchronization. As a result of the mode of OTN+PTN joint networking the OTN equipment deployment in the core network backbone layer the PTN equipment deployment in the aggregation and access layer, the time source first deployed in the side of the local network core equipment room RNC, RNC first time synchronization information passed to the core layer PTN core layer PTN, passed to the core layer of the OTN equipment, the OTN equipment then in turn transmitted to the other layer PTN equipment for precise time synchronization of the whole network. Currently the 1588v2 protocol has become PTN PTN carrying a basic technology, mainstream manufacturers have been a lot of testing. If using OTN+PTN joint networking mode, the requirements OTN supports the precise time transfer function, this is a new research topic has been very clear and realistic demand, but the maturity of the technology apparently has not yet reached the time with PTN sendstage synchronization par. From mainstream manufacturers the OTN send time synchronization technology point of view, the current implementations, there are three: the transparent transmission scheme 1 GE/10 GE, OSC with overhead transfer program the outer transfer programs, as well as the OTN band, the actual networking based on demand, as well as send the advantages and disadvantages of different options to choose or combination of applications.
3. The Protection Issues
Network safe at all, regardless of the OTN, PTN network, need to consider unified network protection. OTN equipment deployed in the core network backbone layer the PTN equipment deployment in the aggregation and access layer, between all levels often requires a large number of service interworking and scheduling, protection for the business needs of the end-to-end or section.
4. Interface Issues
In the metropolitan area network and local area network, often data services occupy the mainstream of the business, in particular, GE, 10 GE interface consistency should be noted that in the interface in the network, and 10 GE signal, for example, serveral 10 GE LAN signal OTN network mapping ITU-T defined G.709 and G.sup43, the standard GFP-F G.sup436.2, ODU2e way G.709.1.4 and expansion GFP-F/OPU2 way G.709 17.3.1, should maintain the consistency of the package, and mapped signal.
5. Network Management Issues
PTN and OTN mainstream manufacturers in the industry can achieve a total network management platform to facilitate the maintenance of the network, in general, from the point of view of the network management. Than in PTN and OTN joint-networking mode, OTN often located in the core layer, PTN position in the aggregation, service interworking and scheduling between the access layer, at all levels, so wheter it is in the opening of business, or in the network pipe maintenance needs, and have put forward higher requirements.
6. Maintenance of The Network
In the metropolitan area and the local network, the device level more complex networking, brought no small difficulty to the network fault location. When networking joint OTN+PTN, PTN and OTN technology inherited SDHhierarchical OAM management mechanism, business package, there will be a rich overhead monitor, the OAM PTN including customer layer OAM, channel layer OAM, channel layer OAM and segment layer OAM, OTN support 6 levels of TCM, SM, PM, etc., each layer will provide fault and performance, so as to realize the OAM in different level real-time, accurate fault location function.
