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Issue generation SDH standard
From;    Author:Stand originally
SDH” of the generation below “ is a term that contains a few new ITU-T SDH standards, the occurrence of these standards is to make SDH increases increasingly in deferent network better above all in group data, it is perfect letter next so that your control plane is fast automatically admeasure business. IP and transmit mutual already confluence, and the means of settlement with the problem new need that the rapid growth of data business brings about.
  
The defect of traditional SDH

Although SDH is designed to be used,transmit data, but it is developed before Internet appears. Grow a few percent photographs every year to compare with business of one's voice in speech, when in group business begins with annual when the rate of 100 % rises, the system is a bit nervous. Accordingly a lot of defect of SDH become a topic that discusses inside course of study.

The reapportion of bandwidth is to pass the administrative system of a concentration to offer those who will come true afresh, often include to a complete handmade requests and buy a process. This fits trends of business of high capacity data and uncertain character not quite.

Transmit in SDH when data when, connect regular meeting to be like PPP and POS to come by the agreement that designs to other applying or the agreement that had not standardized map. New agreement, be like aether net, FICON and ESCON, become important, different cause compatible problem too much with proprietary map.

The SDH before answer in using a structure (2/8/34/140Mb/s) , for the best admeasure that data of fourfold increment bisect group sheds too big. Top rate is too low also, the fictitious container of top rate (VC-4, 140Mb/s) to net of data shedding, aether and road by the taller bandwidth that uses in port for too small. Although the fictitious cascade of VC already was standardized did not use extensively however.

The direct way that does not have 2.5Gbit/s or 10Gbit/s by. As the addition of bandwidth, what do not need to pick a way afresh in alternate connection to those is low rank iformation flow undertakes solution answer is used very will costly.

There also is interaction between the high level. All layers, not only SDH, keep apart each other. SDH, ATM and IP are separate network, make only artificially the resource between the layer for instance bandwidth or protection get transferring or use.

These problems arise the uncertainty that flows at taller bandwidth and data, what need higher rate to also need a network already is taller with automatic flexibility. Apparently monolayer is insoluble these problems.





The new standard in SDH

ITU gets a lot of new idea, make all sorts of improvement of SDH standardization. Be in finally 2001, a new ITU-T standard appeared the first version. It is the most important to go up in practice among them as follows:

LCAS of 3.1     (G.7042) - link capacity adjusts plan
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