Application of AOC in Data Center cabling

According to a report by the Communications Industry Research Institute (CIR), the active optical cable(AOC) market for data centers will reach US$4.2 billion (approximately RMB 26.68 billion) in 2020. Active optical cables are used in data center wiring racks, switches, and switches and servers to interconnect, so as to achieve mutual communication between machines.

 

Data centers generally choose to install switches first, then do structured wiring, and finally select appropriate interconnect products to connect to the network.

 

For ultra-short distances (<90m@10G and <10m@40G), copper cables are the cheapest option;

 

For medium distances (<500m@10G and 150m@40G), multimode VCSEL (Vertical Cavity Surface Emitting Laser) transceivers are the most suitable choice, and AOC is one of them.

 

More than 500 meters @10G, 150 meters @40G and 100 meters @100G, there are a variety of single-mode transceivers to choose from, and their costs are gradually increasing.

 

Among them, in the integrated cabling of the data center, the server wiring methods include TOR (Top of Rack) cabling and EOR (End of Row) cabling.

 

1, TOR(Top of Rack)

 

The TOR cabling method is to place the access switch on the top of each server cabinet or unit. The servers in the cabinet are directly connected to the switch on the top through short jumpers, and then connected to the core from the uplink port of the switch via copper/fiber optic cables. switch.

2, EOR(End of Row)

 

The EoR cabling method is to centrally install the access switches in a row of cabinets at the end of the cabinet, and connect the host/server/minicomputer equipment in the equipment cabinet with a permanent link through horizontal cables. The equipment cabinet in EoR needs to lay a large number of horizontal cables to connect to the switch. The copper cables/optical fibers on the distribution frame extend to the edge network cabinet, and the access switch is installed in the network cabinet. The rack server is installed in the server cabinet, and the server network card is connected to the patch panel in the cabinet through jumpers (copper cable/optical fiber).

 

As shown in the figure, the EOR cabling method has more copper cables or optical fibers from the server cabinet to the network cabinet, and the farther the server cabinet is from the network cabinet, the longer the wiring distance in the computer room, which leads to a large and flexible cable management and maintenance workload. Poor sex.

The TOR cabling method simplifies the cabling between the server cabinet and the network cabinet. There are fewer copper cables or optical fibers from each server cabinet to the EOR/MOR network cabinet, and it also greatly shortens the distance between the server and the switch. Therefore, TOR The cabling method will be more likely to be adopted by more data center cabling. At the same time, with the expansion of the data center computer room area, the unit computer room area increases and the functional area increases, which increases the transmission distance of the backbone subsystem cable. In this cabling method, the transmission distance is mostly medium distance, so it will be used To a large number of active optical cables.

 

AOC is usually used in the following locations in data centers:

 

Server cabinets; up to 40 servers are connected to the top-of-rack switch (TOR). Each server has one or two Ethernet ports connected to the switch.

 

Main network area; AOC can be used in Spine, Leaf or core switching area. In these areas of today's network, there are a large number of discrete switches, and they all need to be connected to each other to create a large switch architecture. These interconnections are usually implemented using AOC. In some data centers, the switch architecture can occupy multiple cabinets, or even an entire row in the data center.

 

Of course, the choice of AOC is not only due to the distance factor, but also has many advantages as follows:

 

Compared with active optical cables and high-speed cables:

 

1, The transmission power on the system link is lower;

 

2, The volume is about half of the copper cable, and the weight is only a quarter of the high-speed cable;

 

3, In the computer room wiring system, the air flow is better and the heat dissipation is stronger;

 

4, The bending radius of the optical cable is smaller than that of the copper cable;

 

5, The bit error rate of the product transmission performance is also better, and the BER can reach 10^-15.

 

Active optical cable compared with optical transceiver module:

 

1, The optical interface of the active optical cable is not exposed, that is, there is no problem of clean and contaminated optical interface;

 

2, Higher system stability and reliability;

 

3, Make the network system more convenient to manage and maintain;

 

4, Greatly reduce operation and maintenance costs and improve efficiency.

 

From the perspective of the future development trend of data centers, we will advocate all-optical networks in the future and aim to increase network speeds. With the continuous increase of network speeds, AOCs will be widely used in data centers.