Fiber Optic Transport Network DWDM

The Datagroup company owns long-distance fiber optic network of the total length up to 11 500 km. The possible increase of its length till the end of the year 2008 is up to 15 000 km. For the moment there are 190 nodes in the network, connected with the help of failover connection patterns. The network entries for the clients are functioning in all regional centers.

The DWDM was chosen as the core technology while building the network. The transport technology DWDM (Dense Wavelength Division Multiplexing) guarantees the highest speed per one optic pair comparing to other transmission technologies that are used nowadays. The high speed is possible because of the use of the wavelength division multiplexing, when via one optical pair several independent streams are transmitted, each of them in its optics region.

The network is based on the multiservice transport platforms Cisco ONS 15454 MSTP. This solution is one of the newest in the sector. The ROADM optic input/output multiplexers with adaptive configuration are the part of the solution. Such multiplexers allow creating 32 virtual channels per one optical pair, each of these virtual channels can be of 2,5 or 10 Gpbs speed of data transmission; this depends on the transponder modules that are installed in the multiplexer.

In general, at the moment the potential capacity of the network is 320 Gpbs. The maximum capacity of the network in future will be about 2560 Gpbs.

The appliance of DWDM technology allows:

• To divide one physical pair of optical fibers into several “virtual” ones, that increases the effectiveness of the usage of optics;
• To start the separate kind of the services on each “virtual” optical fiber, that is not connected to the services performed on other “virtual” fibers;
• To start any existing telecommunication service, realized on the basis of existing technologies (MPLS, Frame Relay, TDM, SDH, IP, ATM etc.) without reconfiguration of the core optic network and the termination of the services that have been started earlier;
• To be ready to the quick implementation of the new kinds of services (that are on the project stage at the moment) and to increase the capacity of the core optic network without its reconfiguration and termination of the services that have been started earlier.

The network gives the possibility to provide modern telecommunication services to the service providers, internet providers and corporative clients.

Mai advantages of using DWDM network are:

• High speed of transmission;
• High utilization of optic fiber;
• The possibility to provide 100% safety thanks to RN;
• The usage of any kind of technologies of channel level thanks to the transparency of the channels of the optic fiber;
• The possibility of simple increasing of the channels in the optic backbone.

The DWDM equipment ONS 15454 is also installed on the connection node of the Frankfurt city (Germany), to which two independent international fiber optic junctions are built. The connections to the international operators are established, the connection to the world backbones of the Internet is established (Sprintlink, ReTN, Linxtelecom, РТcom) as well.