Active Optical Cables: Transforming Data Center Infrastructure

As per a report from the Communications Industry Research Institute (CIR), the market for active optical cables (AOCs) in data centers surged to $4.2 billion (approximately RMB 26.68 billion) in 2020. AOCs play a crucial role in linking data center cabling racks, switches, and facilitating communication between switches and servers. Typically, data centers prioritize switch installation followed by structured cabling, culminating in the selection of appropriate interconnect products for network access.

• Over short distances (<90m@10G and <10m@40G), copper cables are the most economical choice.

• For medium distances (<500m@10G and 150m@40G), multimode VCSEL (Vertical Cavity Surface Emitting Laser) transceivers emerge as the preferred option, with AOCs being a notable inclusion.

• Beyond the specified distances, various single-mode transceivers are available, albeit with increasing costs. Within integrated data center cabling, server connectivity commonly employs either the TOR (Top of Rack) or EOR (End of Row) cabling methodologies. To know more details about ToR and EoR, check out the article about ToR vs EoR

AOC for Data Center ToR Cabling

The ToR cabling method involves positioning the access switch atop each server cabinet or unit. Servers within the cabinet are directly linked to this top switch using short patch cables. Subsequently, the connection extends to the core switch from the uplink port of the switch, utilizing either copper or fiber cables.

AOC for Data Center EoR Cabling

The EoR cabling method entails centrally installing the access switch within a cabinet situated at the end of a row of cabinets. Hosts, servers, or mini-computer equipment within the equipment cabinet are interconnected to the switch via permanent links utilizing horizontal cables. This method requires laying a substantial number of horizontal cables within the equipment cabinet to establish connections to the EoR switch. Additionally, copper or fiber optic cables from the wiring closet are extended to the network cabinet located at the side end. Access switches are then installed within the network cabinet. Rackmount servers are housed within server cabinets, with server NICs connected to patch panels in the cabinets via patch cables, which can be either copper or fiber.

As depicted in the illustration, the EOR cabling method involves a higher density of copper cables or optical fibers extending from server cabinets to network cabinets. Furthermore, the farther these cabinets are from the network cabinets, the greater the distance covered by cabling within the server room. This results in a substantial burden on cable management and maintenance, along with reduced flexibility.

In contrast, the TOR cabling method streamlines the connections between server cabinets and network cabinets. The number of copper cables or optical fibers required from each server cabinet to the network cabinets of EOR/MOR is minimized, significantly shortening the distance between servers and switches. Hence, TOR cabling is more likely to be favored in data center cabling scenarios. Additionally, the expansion of data center server room area results in increased unit server room size and functional area, consequently lengthening the transmission distance of the backbone subsystem cable. This cabling method primarily involves medium-distance transmission, thereby necessitating the use of a large number of active optical fiber cables.

Active Optical Cables (AOCs) find extensive application in data centers, particularly in server cabinets where up to 40 servers are connected to a top-of-rack switch (TOR). Each server typically has one or two Ethernet connections to the switch. Additionally, AOCs are deployed in the main network areas such as the Spine, Leaf, or core switching area. These areas comprise numerous discrete switches interconnected to create a large switch fabric. AOCs are commonly used to implement these interconnections, with the switch fabric potentially spanning multiple cabinets or an entire row within the data center. The selection of AOCs is driven by more than just distance considerations; their numerous advantages make them the preferred choice for data center cabling.

Data Center Cabling Selection: AOC vs DAC vs Optical

Active Optical Cable vs Direct Attach Cable

• Reduced power transmission over the system link.

• Approximately half the size of copper cable and a quarter of the weight of high-speed cable.

• Improved airflow and heat dissipation within server room cabling systems.

• Smaller bend radius of fiber optic cable compared to copper cable.

• Enhanced Bit Error Rate (BER) of product transmission performance, with BER reaching up to 10^-15.

Active Optical Cable vs Optical Transceiver Modules

• Active optical cables feature enclosed optical interfaces, eliminating concerns regarding cleaning and contamination.

• Offers greater system stability and reliability.

• Enhances the manageability and maintenance of network systems.

• Drastically reduces operation and maintenance costs while improving efficiency.

Conclusion

Considering the future trend of data center development, there is a growing endorsement for all-optical networks, to enhance network speed. As network rates continue to advance, active optical cables (AOCs) are expected to be extensively utilized within data centers. FS offers a comprehensive range of AOCs and data center cabling solutions that provide superior performance and unmatched reliability.