Both 25G high-speed copper cable (DAC) and 25G active optical cable (AOC) can achieve 25Gbps data transmission, but what is the difference between them?  COMNEN will focus on the difference between these two cables in this article.

100G QSFP28 to 4x25G SFP28 Breakout Active Optical Cable (AOC)

100G QSFP28 to 4x25G SFP28 Breakout Active Optical Cable (AOC)

1. Definition of 25G high-speed copper cable and 25G active optical cable

1). 25G high-speed copper cable:

25G high-speed copper cable adopts silver-plated conductor and foamed insulated core wire, which has excellent attenuation performance and low delay performance, so that the signal transmission is correct, and the transmission speed can be improved. It is a short-distance connection solution instead of optical modules. The price is much cheaper than the same type of optical module, and it is widely welcomed in short-distance connection applications.

2). 25G active optical cable:

25G active optical cable can overcome the bandwidth limitation of traditional high-speed copper cables, and this 25G active optical cable can provide an ideal alternative solution for high-speed cables and short-distance SFP28 optical modules, with more complete signals and higher performance. Therefore, it is widely used in high-speed, high-density, and low-power data center networks.

2. Structure of 25G high-speed copper cable and 25G active optical cable

The 25G high-speed copper cable is composed of a copper cable and fiber optic transceivers at both ends. The connector used is similar to the interface of the optical module, but the connector module on the high-speed copper cable does not have expensive lasers, which greatly reduces the cost of short-distance applications.

The 25G active optical cable is composed of optical fiber transceiver devices at both ends and OM3 or OM4 multimode fibers of different lengths. The transceiver devices at both ends can provide photoelectric conversion and optical transmission functions, which ensure the stability of data transmission and the flexibility of applications.

3. Classification of 25G high-speed copper cables and 25G active optical cables

1). 25G high-speed copper cable:

There are two types of 25G high-speed copper cables: 25G SFP28 to SFP28 DAC and 100G QSFP28 to 4 *SFP28 DAC.

25G SFP28 to SFP28 DAC is a very cost-effective solution for short-distance link transmission. It can establish a 25G link through the SFP28 port of the switch. It conforms to IEEE P802.3by and SFF-8402 SFP28 standards and is widely used in the data center or supercomputing center system scenario.

100G QSFP28 to 4 SFP28 DAC is suitable for stacking and assembly between short-distance big data devices. One end is 100G QSFP28 interface, and the other end is 4 *25G SFP28 interfaces, which can provide customers with 100G data transmission, in line with IEEE802.3BA standard , SFF-8665/SFF-8679, IEEE 802.3bj and InfinibandEDR standards.

2). 25G active optical cable:

There is only one type of 25G active optical cable, 25G SFP28 AOC. The transmission distance of 25G SFP28 AOC and OM3 multimode fiber can be up to 70m when used together, and the transmission distance can be up to 100m when used together with OM4 multimode fiber. It is suitable for short-distance data communication and interconnection applications and provides a cost-effective way to the connection with a rack and adjacent racks .

4, The characteristics of 25G high-speed copper cable and 25G active optical cable

1). Comply with SFP28 MSA, SFF-8402, SFF-8432 and RoHS standards;

2). Support hot swap function with low insertion loss;

3). Enhanced EMI performance.
5. Application of 25G high-speed copper cable and 25G active optical cable

25G high-speed copper cables are mainly used in switches/routers/HBA, servers and data storage devices, 40Gbs/100Gbs Ethernet, and Fiber Channel.

25G active optical cable is suitable for 25G and 10G Ethernet, high-capacity IO and SFP+ interface, data center and inter-rack connection.

6. What are the benefits of using 25G high-speed copper cables and 25G active optical cables?

1). 25G high-speed copper cable:

25G high-speed copper cable can support a transmission rate of up to 25Gbps, which is higher than the data transmission rate supported by traditional copper cables;

25G active optical cable is suitable for 25G and 10G Ethernet, high-capacity IO and SFP+ interface, data center and inter-rack connection.

2). 25G active optical cable:

The volume and weight of 25G active optical cable are one-half and one-fourth of 25G high-speed copper cable, so 25G active optical cable is much lighter than 25G high-speed copper cable; no equipment upgrade is required, 25G active optical cable has up to 25Gbps throughput; 25G active optical cable has better transmission performance and bit error rate, BER can reach 10-15; 25G active optical cable has lower transmission power on the system link.
7. Prospects of 25G high-speed copper cables and 25G active optical cables

25G technology is the basis of the 100G (4*25Gbps) Ethernet standard, and compared with 40G technology, 25G technology can provide higher port density, while also reducing costs, so the prospect of 25G technology is very impressive. At present, under the strong promotion of the 25G Ethernet Alliance, cloud computing giants such as Microsoft and Google have proposed 25G and 50G Ethernet solutions.

In addition, according to data from Dell’Oro, the rate of next-generation servers will reach 25Gbps, which means that more devices will choose 25G SFP28 DAC or AOC as the best network solution.