Virtual Containers Research Articles

Optical Transmission Network Evolution Scheme of VC-OTN

With the evolution of operator network, the optical transmission network (OTN) technology which integrates the cross-function of Virtual Container (VC) has become a hot research topic. In this paper, the application scheme of VC-OTN technology including network structure planning, network evolution steps and protection scheme in transmission network is proposed. The pilot project proves that the proposed scheme can significantly guide the operator network construction.

The Influence of Transport Layer to Ethernet Services Quality

Questions were analysed regarding the influence of SDH network nodes configuration specifics and TCP and UDP transport protocols on to Ethernet data transferring quality. The influence of virtual container (VC) size on ADM performance was revealed by means of mathematical model created, and it was determined, that the better choice was choosing the larger size VC, because of the smaller packets loss values obtained. The real experiments in STM-1 network helped in solving which transport protocol would be more suitable for data transferring. In case of TCP investigation, TCP windows or VC group formed in ADM size have showed the high and direct influence on to network throughput obtained, because the larger TCP windows applied assured the bigger amount of data transmitted at once. This would be meeting the requirements of Ethernet technology very effectively in high rates. The analysis of UDP showed that the most optimal UDP datagram size for Ethernet packets transferring would be of 800 – 1000 Bytes order. Investigation of UDP suitability for voice packets transferring showed that even if the smaller packet loss will have an insignificant influence on to final quality of real time services, the larger voice packets (800 – 1000 Bytes order) will assure better network throughput, smaller packets loss and Jitter values.

The impact of mapping wander on the performance of SDH AU-4 and TU-3 uniform pointer processors

Pointer processors in Synchronous Optical Networks (SONET)/Synchronous Digital Hierarchy (SDH) networks may be placed into three categories: fixed threshold, adaptive threshold modulation and uniform. Fixed threshold pointer processors produce gapped pointer sequences during SONET/SDH holdover mode, when one or more node's clock has lost its synchronization reference, as a result of the periodic effects of the SONET/SDH frame overhead bytes. These gapped pointer sequences cause mapping wander in the underlying Plesiochronous Digital Hierarchy (PDH) payloads. Uniform pointer processors can smooth the gapped pointer effects caused by the Synchronous Transport Module (STM), Administrative Unit (AU) and Tributary Unit (TU) overhead bytes. However, uniform pointer processors cannot remove the additional gapped pointer effects caused by the Virtual Container (VC) overhead bytes. Mathematical analysis and simulation results, for fixed threshold pointer processors in SDH networks where VC-3 uses TU-3 to transport an E3-rate PDH payload or VC-4 uses AU-4 to transport an E4-rate PDH payload, illustrate the wander caused by the gapped pointer effects. A proposed uniform pointer processor algorithm shows the residual mapping wander caused by the VC-3 and VC-4 overhead bytes. Finally, a lower bound on the Maximum Time Interval Error (MTIE) that can be achieved with a uniform pointer processor is calculated for these two cases.

Pointer conversion method for synchronous digital hierarchy

AbstractSynchronous digital hierarchy (SDH) standardized in International Telecommunication Union‐Telecommunication Standard Sector (ITU‐T) applies a new multiplexing method using a pointer that indicates a tributary location in the SDH frame. the location of the SDH frame heads received from several lines is adjusted at interface circuits to facilitate the multiplexing process in the SDH equipment. Since the frame head locations of input signal differ from the output signal, pointer values are attached to the output signals. the pointer conversion of each tributary is performed independently of each other. Therefore the pointer values of tributaries transported on the same line might be different from each other after the conversion even if these values are the same. Hence large amounts of buffer memory would be required at the destination point to provide a transport service utilizing multiple virtual containers (VCs). This paper proposes a new pointer conversion method that keeps the pointer value differences unchanged between tributaries multiplexed in an SDH frame. This method allows multiple VC transport service to be provided.

CCITT standardization of network node interface of synchronous digital hierarchy

The main concepts and interfacing and multiplexing techniques for an NNI (network node interface) as set forth in CCITT (International Consultive Committee for Telephone and Telegraph) Recommendations are described. The objectives and history of the NNI standardization are reviewed together with concepts, basic requirements, and features of the NNI. The nine-row-based frame structure and the virtual container (VC) concept, which are the main features of the NNI, are introduced. The multiplexing principle and method, the detailed frame structure and overhead, and mapping methods related to the NNI are described. Applications of the NNI in the synchronous network and international interworking are presented. The future application of asynchronous transfer mode (ATM) is discussed. >