How to Determine the Number of Cores Used in an Optical Fiber


Optical fiber, short for optical fiber, is a fiber made of glass or plastic that acts as a light-transmitting tool. The transmission principle is 'total reflection of light'. The number of optical fiber cores is related to the device interface connected by the optical fiber and the signal communication method of the device. Generally speaking, the number of optical cores in the optical cable is the total number of device interfaces multiplied by 2, plus 10% to 20% of the spare number, and if the communication mode of the device includes serial communication and device multiplexing, it is necessary to Can reduce the number of optical cable cores.


Number of fiber cores

Determination of the number of fiber cores

According to the IBDN standard, it is generally recommended that 12 cores be used in the communication room in each building, and 24 cores should be used between buildings.


Consider this:

First clearly know the number of wiring points on this layer, calculate the number of switches, and whether the connections between switches are stacked or not.


If the stack is stacked and the core switch is dual-machine hot standby redundancy, 6 cores are enough (2 cores each use 2 cores, and 2 cores are redundant).


If it is not stacked, a switch needs 4 cores, and the number of switches multiplied by 4 plus the redundancy of 4 cores is enough.

fiber optic cable

Experience and practice: each floor wiring room (horizontal wiring cabinet), set up an optical fiber.


Generally six-core: two-core use, two-core backup, two-core redundancy; there are also eight-core optical fibers.


Noun Notes:

Redundancy: as long as there is more than what is used, the excess is called redundancy;


Active and standby: one is used, and the other is exactly the same as standby;


Hot backup: both in working state at the same time


Cold Backup: The backup device is in standby


1. In general, there are several terminals that require several cores, but redundancy will be considered in the actual scheme design and construction, so two cores are often used for each terminal. If the cost is considered, the entire line can be redundant 1-2 For example, if you have three optical fiber access switches, you need to have three cores (actually use four-core optical cables), because there is basically no single-core optical cable except for one-core optical fiber, such as: three-core, five-core, etc. , Of course, it is not absolutely that an optical core can only be connected to one terminal device, and multiple terminals can be connected in series on one optical core, but this requires multiple welding, and the light attenuation is large, so long-distance transmission cannot be achieved.


2. The problem of single-mode and multi-mode: multi-mode is actually a single optical core that can transmit multiple data at the same time, while single-mode can only transmit one data at the same time, so the quality and distance of single-mode transmission are better than multi-mode. Therefore, single-mode is mostly used for long-distance outdoor transmission.


3.First of all, there are several systems that use optical fibers. For example, for a certain optical node, the application system has network and monitoring. Among them, the network only needs one route, and it needs to occupy two core fibers; there are 4 channels of images for monitoring, and a 4 channel video optical transceiver needs to be installed, which needs to occupy one core fiber. Then from the computer room to the optical node, a total of 3 cores of optical fiber are required, and the optical cable design from the computer room to the optical node is a 6-core optical fiber cable, of which 3 cores are redundant. Considering the cost, build a single-mode fiber optic cable. In fact, a 6-core single-mode optical fiber cable should be pulled to the optical node.


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