The number of fiber cores is mainly related to the device interface connected by the fiber and the communication mode of the device.
Generally speaking, the number of optical cores in an optical fiber is the total number of equipment interfaces multiplied by 2, plus 10% to 20% of the spare quantity, and if the communication mode of the equipment has serial communication and equipment multiplexing, you can reduce the number of cores.
According to the IBDN standard, it is generally recommended to use 12 cores for the communication room in each building, and 24 cores for the building room.
Of course, this is a general situation, and specific words can be considered according to the following criteria.
1.First clearly understand the number of wiring points and calculate the number of switches.
Whether the connections between switches are stacked is also one of the considerations.
Stacking: If the core switch is dual-machine hot standby (both are working at the same time) for redundancy, 6 cores are sufficient (2 cores each use 2 cores, and 2 cores are redundant).
No stacking: A switch needs 4 cores, the full number of switches are multiplied by 4 plus 4 cores for redundancy.
2. Under normal circumstances, there are several terminals and several cores are needed.
However, redundancy will be considered during the design and construction of the actual scheme, so each terminal will use two cores at most.
If you want to consider the cost, you can also use 1-2 cores for the entire line redundancy. For example, if you have three optical fiber access switches, you need to have three cores (actually use a four-core optical cable).
This is because apart from one-core optical fiber, there are basically no optical cables with an odd number of cores, such as: three-core, five-core, etc. Of course, it is not absolutely true that one optical core can only be connected to one terminal device, and it can also be connected in series on one optical core. Multiple terminals, but this requires multiple splicing, the optical attenuation is large, and long-distance transmission cannot be realized.
3. Multimode and singlemode
A multi-mode optical core can transmit multiple channels of data at the same time, while single-mode can only transmit one channel of data at the same time.
Therefore, the quality and distance of single-mode transmission are better than those of multi-mode, and single-mode is mostly used for long-distance outdoor transmission.
4.Count how many systems will use optical fiber
For example, for an optical node, the application system includes network and monitoring.
Among them, the network only needs one route, occupying 2-core optical fiber; monitoring has 4 routes, occupying 1-core optical fiber.
A total of 3 core fibers are required from the equipment room to the optical node.
The design of the optical cable from the computer room to the optical node is a 6-core optical cable, of which 3 cores are redundant.
Considering the cost, building a single-mode optical cable is actually to pull a 6-core single-mode optical cable to the optical node