[Integrated Wiring] The difference between AOC and DAC for 10G SFP+ cables

10G SFP+ Cables: Definition and Types

SFP+ cables are high-speed cables with SFP+ transceivers on both ends. The transceivers at both ends transmit and receive 10Gbps data over a thin twisted pair or fiber optic cable through a pair of transmitters and receivers. They are suitable for in-rack connections between servers and switches, providing significant cost and resource savings in short-distance applications. 10G SFP+ cables can be divided into two types: 10G SFP+ DAC (High-Speed Cable) and 10G SFP+ AOC (Active Optical Cable).

10G SFP+ DAC

10G SFP+ DAC is divided into passive DAC and active DAC, consisting of:Made of twisted pair copper cable, the factory pre-installed light access module, which can directly connect the cable to the device. The former can transmit data without signal conditioning, while the latter has electronic components inside the transceiver to enhance the signal. 10G SFP+ DAC cables are ideal for short-distance rack-to-rack connections with cost budget control.

10G SFP+ AOC

10G SFP+ AOC is a combination of optical components and electronic or active electronic components that require an external power supply to complete the signal conversion. It usesFiber optic cables and silicon chips, providing electricity-to-light conversion to enhance the signal and performance of the cable. 10G SFP+ AOC cables are typically used in end-of-rack or intermediate data center architectures with interconnect distances of up to 15 meters.

Advantages of SFP+ cables:

cost: Because it does not require high-cost electronic components, 10G SFP+ cables tend to be cheaper than 10G optical modules. And because the power consumption is less than 0.15W, the operating cost of the passive DAC will be lower.

Convenience: In actual installation and deployment, the use of 10G SFP+ cables is more flexible and simple. Simply plug the SFP+ cable directly into the user's physical device, such as a network switch, and the connection is achieved without any additional signal processing or conversion.

Application of SFP+ cables

10G SFP+ DACs and AOCs are widely used in data centers to connect servers, storage devices, and switches. In general, these cables are particularly suitable for the following two application scenarios.

10G SFP+ DAC cable: Server and switch connection

10G SFP+ DACs are typically used for interconnection between 10G ToR (top of rack) switches and servers, or for stacking of 10GbE switches. Because 10G SFP+ DACs typically support a link length of 7 meters, they are ideal for short-distance server-to-switch connections due to their low power consumption, low latency, and low cost.

10G SFP+ AOC cable: Switch-to-switch connection

Because 10G SFP+ AOC supports longer distance connections, it is often used in multiple locations in data centers, such as ToR (top of rack), EoR (end of rack), and MoR (middle of the rack). Therefore, 10G SFP+ AOC cable assemblies are a high-performance and cost-effective I/O solution for 10G Ethernet and 10G Fibre Channel applications. Due to its theoretical maximum transmission distance of up to 100 meters, 10G SFP+ AOC cables are often used for switch-to-switch connections.

Guidance on the purchase of 10G SFP+ cables

Generally, four factors should be considered before deciding whether to buy a 10G AOC or a 10G DAC:

Dimensions and bend radius

10G AOCs use fiber optic cables as the transmission medium, which is smaller and lighter in weight compared to 10G DACs. As a result, it can be flexibly deployed where space is strictly limited and can be transported from one place to another. In addition, the bend radius of 10G SFP+ AOC is significantly smaller than that of 10G SFP+ DAC, making 10G AOC cables more suitable for high-density cabling scenarios.

power consumption

10G SFP+DAC cables are passive devices with little to no power consumption, which is much lower than 10G AOC cables, so the operating cost is lower.

Transmission distance

10G AOC can transmit distances of up to 100 meters, while 10G DAC has a maximum transmission distance of 10 meters (passive DAC - 7 meters; Active DAC - 10 meters). Therefore, 10G SFP+ DAC cables are suitable for short-distance scenarios, while AOC solutions are suitable for longer-distance network scenarios. (Note: The maximum transmission distance of the signal on a 10G DAC cable depends on the data rate.) As data rates increase, link lengths decrease, for example, 100G DAC cables can only transmit up to 5 meters. ）

Anti-electromagnetic interference

Electromagnetic interference (EMI) refers to interference generated by external sources that can affect the normal operation of a circuit. Since the cable type of 10G SFP+ AOC cables is fiber, they are immune to electromagnetic interference during data transmission, while 10G DACs can be susceptible to electromagnetic interference, such as poor response and reduced performance. If the network has special requirements for EMI, 10G AOC will be an ideal solution for secure transmission in large data center networks.

summary

In short, SFP+ direct attach cables can provide you with a cost-effective, low-power, short-distance transmission solution. In general, 10G SFP+ DAC cables are ideal for short-distance applications within racks, while 10G SFP+ AOC cables are suitable for rack-to-rack connections between ToR and EoR switches. You can choose SFP+ cables according to your network needs.

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