In the early construction period of fiber optic network resources are relatively abundant, are dual-fiber mode when used in the metropolitan area for internal use, but with community access and commercial increase in the number of fiber resources used more and more. Our previous approach using dual fiber GBIC / SFP expansion to double the bandwidth of a single fiber, if we further expansion of the use of any way to be considered. The following describes the use of Coarse Wavelength Division Multiplexing (CWDM) combined GBIC / SFP way, this program should have been widely used in other carriers. From the cost and stability considerations are more suitable for line length and width expansion and Chengwanggaizao application, the following brief description of the program. The program consists of two parts: a set of CWDM GBIC modules can be selected or SFP, one pair of passive wave division multiplexing together multiplexer.
Multi-channel multiplexer demultiplexer contain four waves, wave 8 or 16 waves, etc., 8 wave typically used 1470nm to 1610nm, if expanded to 16 waves 1270nm ~ 1610nm, 1370nm and 1390 in addition, the wavelength spacing of 20nm. Also need to select the corresponding wavelength GBIC / SFP, 1470nm to 1610nm wave device 8 used more easily purchase. Including transmission distance 40KM, 80KM, 120KM variety, the maximum transmission rate has 1.25Gb / s and 2.5Gb / s two kinds.
If that is not enough to use 16 channels can be combined in a multi-channel partial wave 1550nm wavelength multiplexer does not use, you can use the reserved DWDM upgrade.
Star-shaped or ring-shaped
Centrally located in the core node multiplexer, through single-mode optical fiber is connected to a plurality of nodes, each node can select one or more channels. If you have a fiber loop between multiple nodes, you can achieve the fiber loop clockwise or counterclockwise according to core resources, protected fiber interruption of business.
Aggregation nodes are connected to each channel in both directions, are connected to the core nodes, each node to select the appropriate wavelength CWDM modules. Flexibility to choose according to each city line resources, you can select the number of channels required bandwidth for each node.
Due to resource constraints, if only one fiber, but there are bandwidth expansion needs, you can use different wavelengths as a transceiver. Thus, four channels can be implemented on one fiber. Such mode selection device, select two different wavelengths CWDM module.