Applications of Fiber Optic Cables

Two pairs of fiber optic cables connect with a manageable data center hardware, like Internet Switch, Router, Server, Storage, etc. It contains the concept of high-speed data transmission and modern Internet technology.

The application of fiber optic cables is as follows :

  • Local area network, the configuration of the data center, metropolitan network, and FTTH
  • Connection of distribution boxes and optoelectronic equipment
  • Optical testing equipment
  • Component connection of long-distance optical communication systems
  • Telecom, data, voice, and image applications

Introduction of Fiber Optic Connectors

LC

The LC connector is a small form factor (SFF) connector that utilizes traditional components of standard connectors with a 1.25mm ceramic ferrule, and is commonly seen in router connections.

FC

The FC connector is a fiber-optic connector with a threaded body, which is designed for use in high-vibration environments. It is commonly used with both single-mode optical fiber and polarization-maintaining optical fiber. FC connectors are used in datacom, telecommunications, measurement equipment, and single-mode lasers. They are becoming less common and displaced by SC and LC connectors.

ST

Like the BNC connector for coaxial cable, ST connector has a bayonet based mounting end and a long cylindrical ferrule, which is a spring-loaded sheath used to hold fiber in place. The connector is inserted into a receptacle and twisted to lock it into place. Sticking and twisting are considered older technology, but ST connectors  are still widely used on data networks, and their install base is broad.

SC

SC connector is a relatively new connector-type technology, but it is popular today. A main reason of their popularity is that SC connector is cheaper and easier to use than ST connectors, and less prone to damage. You would most likely see them from large core switches with fiber uplinks to smaller closet switches in campus network.

MTP / MPO

MTP/MPO is typically used in data center as they are commonly utilized for high-density, high-speed, and space-saving applications. MTP/MPO connectors are more and more popular in fiber world because they provide fast connection speeds and superior reliability in limited installation space.  

MTP / MPO Connector

How to Use Type A ?

Application of MTP Type A

( Straight-through)

The fibers with type A MTP/MPO are in parallel so that the fiber located in Position 1 (Tx) arrives at Position 1 (Rx) at the other end. That is, Position 1 corresponds to Position 1… Position 24 corresponds to Position 24.

The orientation of the key keys on both ends is opposite. That is, key up corresponds to key down.

Situation 1

Situation 2

How to Use Type B

Application of MTP Type B

( Reversed)

The fibers with type B MTP/MPO are reversed. In type B, the fiber located in Position 1 (Tx) arrives at Position 12 (Rx) at the other end and the fiber located in Position 12(Tx) arrives at Position 1 (Rx) at the other end.

The orientation of the key keys on both ends is the same. That is, key up corresponds to key up and key down corresponds to key down.

Situation 1

Situation 2

MTP/MPO with reversed fibers is widely used, especially used to connect 40G QSFP+ transceiver and 10G SFP+ transceiver.

How to Use Type C

Application of MTP Type C

( Pairs Flipped)

In Type C, each adjacent pair of fibers at one end are flipped at the other end. The fiber at position 1 on one end is shifted to position 2 at the other end of the cable. The fiber at position 2 at one end is shifted to position 1 at the opposite end.

The orientation of the key keys on both ends is opposite. That is, key up corresponds to key down.

Situation 1

How to Deploy 10G / 40G / 100G in the Same Network with Fiber Optic Cable?

Although 40G QSFP+ and 100G QSFP28 are widely used, most data center networks have not replaced all 10G equipment with 40G or 100G equipment. On the contrary, in most cases, 10G, 40G, and 100G will coexist in the same network. So how to deploy 10G/40G and 100G in the same network?

40G QSFP+ to 10G+

As the following figure, the upgraded 40G switch needs to use 1×24 core to 3×8 core MTP trunk cables to connect with the existing 10G server. On the switch, the 24-core fiber panel can be connected to 24-core optical fiber cables and supports three 40G ports. In the server rack, each 40G port can realize a 10G LC connection to facilitate the deployment of servers.

Note:

In this structure, if you have an existing 12-core MTP trunk cable, you can use two 12-core MTP Fiber Cassettes to connect 3×8 core MTP trunk cable instead of redeploying 24-core MTP trunk cable. However, if your network application is more complex, it is recommended to directly use the 24-core MTP trunk cable to make it easier to successfully implement the network upgrade.

CFP2 100G端口 (10×10)

CFP2 100G Port (10x10)

The following figure also shows a similar situation to the existing 10G server, but it uses a 100Gbase-SR10 port on the switch. At this time, a 24-core fiber connector is required to connect to the 10×10 optical module port. It should be noted that the 8-core fiber patch cable is not used here to connect, but a 24-core MTP trunk cable is used to connect the switch to the fiber cassette on the top of the rack. The 24-core MTP trunk cable can connect the switch and the server rack, and the MTP fiber cassette on the top of the server rack can convert 100G ports into 10x10G ports with LC connectors.

Note:

In this case, if you already have two 12-core MTP trunk cables, you can use the MTP adapter panel with 12 ports, and then use 2×12 cores to 1×24 cores MTP trunk cables to create same channel on the switch.

Redeploy 40G/100G network

Below figure is an example of redeploying 40G and 100G networks. Without any 10G switches in Fibre Channel, 40G/100G can be used directly. This method is suitable for 40G or 100G ports of core switches and 40G uplinks of ToR switches. In addition, the MTP adapter panel can be used on the top of each rack, and all 8-core fiber patch cables can realize the connection between the QSFP+ port and the QSFP+ port.

Note:

In this structure, we can use 24-core fiber patch cable to connect to 40G ports, or each branch can be equipped with 8-core fiber patch cable, so that each 40G or 100G port has 8-core cable. In addition, this method effectively avoids the use of 12-core MTP trunk cable.

Generally speaking, network upgrades require the removal of the previous cabling structure and re-cabling, but deploying 10G, 40G and 100G in the same network can effectively avoid expensive network upgrade costs.