High-speed interconnections engineered for strict signal integrity and compatibility
As the backbone of high-density architectures, 25G SFP28 Direct Attach Copper (DAC) cables represent the standard for short-reach, high-speed networking solutions. Operating directly over Twinax copper, these passive assemblies bypass the high power requirement and cost of active optical transceivers. For global operators, multi-tenant data centers, and enterprise clouds, sourcing high-quality ODM 25G SFP28 DAC cables with guaranteed multi-vendor compatibility is essential for maintaining operational reliability and cost control.
In response to data capacity limits, networking topologies are evolving rapidly from legacy 10G to 25G and 100G architectures. The 25G SFP28 interface leverages the physical layout of the SFP+ form factor while scaling signal modulation up to 28 Gbps per channel. This design minimizes structural modifications at the hardware level while providing a 2.5x throughput improvement.
Passive Direct Attach Copper cables remain a highly efficient option for Top-of-Rack (ToR) switch-to-server interconnects. Because passive copper cables consume virtually zero electrical power and generate no heat, they support sustainable green data center targets. Additionally, they deliver low latency by avoiding the optical-to-electrical signal conversion step.
To maintain transmission performance over passive copper pathways, designers must manage insertion loss, crosstalk, and electromagnetic interference (EMI). The standard 25G SFP28 passive copper cable from Kocent Optec is built to meet SFF-8402 electrical specifications, SFF-8432 mechanical parameters, and the IEEE 802.3by 25GBASE-CR Ethernet requirements.
| Parameter | Standard Specifications | Kocent Optec Advantages |
|---|---|---|
| Data Transfer Rate | Up to 28 Gbps per channel | 25GbE & InfiniBand EDR compatibility |
| Available AWG Sizes | 30 AWG, 28 AWG, 26 AWG, 24 AWG | Custom length optimizations from 0.5m to 5m |
| Impedance Target | 100 Ohm differential impedance | Strict 95Ω - 105Ω tolerance control |
| Power Consumption | < 0.1 Watts (Passive) | Zero-power consumption design for high efficiency |
| Standard Compliance | SFF-8402, SFF-8432, SFF-8472, IEEE 802.3by | Fully certified CE, RoHS, FCC, REACH compliancy |
Passive DACs use twinaxial copper lines shielded by aluminum-polyester foil and tinned copper braid. As a result, attenuation increases linearly with frequency and distance. For runs between 1 to 3 meters, 30 AWG and 28 AWG cables offer adequate flexibility and lower airflow obstruction. For runs between 4 to 5 meters, 26 AWG or 24 AWG conductors are necessary to offset insertion loss and satisfy the IEEE 802.3by CA-N (Cable Assembly No-FEC) and CA-L (Cable Assembly Long) link requirements.
Established in 2012 in Hong Kong as a high-tech communication enterprise, Kocent Optec Limited has grown to become one of China's leading fiber optic termination product manufacturers and solution providers.
We specialize in developing and manufacturing fiber optic communication products spanning passive and active categories for telecommunication systems, enterprise networks, and data center infrastructures. Our custom ODM and OEM cabling architectures are engineered for high-density, low-latency applications.
By leveraging our extensive experience and production capabilities developed over the years, we deliver reliable performance for our clients. We emphasize close customer collaboration and position ourselves as a valuable partner in high-performance networking connection designs.
Modern hyper-scale data centers rely on leaf-spine network architectures. In these configurations, top-of-rack (ToR) switches interface with hundreds of servers per row. 25G SFP28 DACs connect these interfaces with low latency, helping prevent bottlenecks during processing-intensive workloads like artificial intelligence and database transactions.
The rollout of 5G New Radio (NR) networks requires high-capacity connections between Distributed Units (DU) and Radio Units (RU). Supporting eCPRI (Enhanced Common Public Radio Interface) protocols, 25G SFP28 DACs enable high-speed transmission in edge locations where operating temperatures and environmental stresses are key factors.
In algorithmic trading networks, every microsecond matters. Optical-to-electrical conversions in transceiver systems introduce minor signal delays. Passive DAC cables deliver speed-of-light propagation delays directly over copper lines, helping minimize latency in time-critical environments.
Our production line combines advanced machinery with strict quality controls. Using automated wire stripping, laser welding, and high-frequency testing equipment, we produce cables that deliver stable signal performance.
One of the main challenges in deploying high-speed networks is the compatibility restrictions imposed by hardware manufacturers. At Kocent Optec, we address this through custom EEPROM programming.
We customize the internal EEPROM microcode of each 25G SFP28 DAC module to match the firmware requirements of target equipment. This ensures compatibility with hardware from major suppliers like Cisco, Arista, Juniper, Dell, HP, and Mellanox, helping operators avoid vendor lock-in.
With more than 13 years of experience in manufacturing telecommunication products, we follow fiber optic and copper cabling standards. We use mature production processes to deliver products on time and ensure that 100% of shipments are tested and inspected.
Our sales and service experience has enabled us to partner with customers across East Asia, Southeast Asia, the Middle East, Europe, South America, North America, and Africa.
Many of our OEM and ODM products have won telecom operator tenders. Our major network partner credentials include deployments with:
What is the difference between Passive and Active 25G SFP28 DACs?
Passive 25G SFP28 DACs contain no active electronic components inside the cable transceiver housing. They rely purely on the host system's ports to manage signal integrity, which limits their effective range to 1 to 5 meters. This design keeps power draw to less than 0.1W. Active Copper Cables (ACCs) feature silicon-based pre-emphasis and equalization chips that help restore signal strength, extending their range up to 7 to 10 meters with power draw around 0.5W to 1W.
How does wire gauge (AWG) affect the performance of 25G SFP28 copper cables?
Wire gauge directly determines copper core diameter and signal attenuation. Thinner wires like 30 AWG have higher resistance and signal loss, making them suitable for short runs (typically up to 1.5 meters). Thicker wires like 26 AWG or 24 AWG reduce attenuation over longer distances, supporting runs up to 3 to 5 meters. However, thicker cables are stiffer and have a larger bend radius, which can impact routing in dense rack layouts.
Are 25G SFP28 DAC cables backward compatible with legacy 10G SFP+ ports?
Yes, the physical SFP28 form factor uses the same mating connector profile as the 10G SFP+ standard. From a hardware perspective, an SFP28 DAC cable can fit into an SFP+ port. However, the system's port controller must be configured via software to negotiate down to the 10G rate (10.3125 Gbps) to establish a stable link.
How does Kocent Optec handle EEPROM programming for multi-vendor switches?
Every manufacturer uses specific security handshakes and vendor keys stored in the SFP28 module EEPROM. Kocent Optec writes custom coding profiles using data gathered from target systems. This allows our cables to bypass system lockouts and operate smoothly with hardware from manufacturers like Arista, Cisco, Mellanox, and Juniper.
What testing protocols does Kocent Optec use for ODM copper assemblies?
We perform eye-diagram and Bit Error Rate (BER) testing on every production run. Using vector network analyzers, we measure insertion loss, return loss, and near-end and far-end crosstalk (NEXT/FEXT) to verify performance limits. This ensures our cables meet the standards required for enterprise deployments.
What are the environmental storage and operating parameters for these DACs?
Our standard 25G SFP28 DAC cables operate across a standard commercial range of 0°C to 70°C. For industrial environments or outdoor cabinets, we can customize assemblies to support an extended operating range of -40°C to +85°C.
How does DAC latency compare to Active Optical Cables (AOC)?
Because DAC cables use electrical copper lines, they avoid the latency introduced by optical-to-electrical converters. This makes their transmission latency virtually negligible (around 10 to 15 picoseconds per meter), whereas AOCs require optical conversion modules that add several nanoseconds of delay.
Can I get customized pull-tab colors and lengths for large data center rollouts?
Yes, as an ODM provider, we can customize cable parameters including jacket color, pull-tab pull-ring lengths (e.g., standard, extra-long, custom pull-straps), custom labeling, and custom cable lengths (e.g., 1.25m, 2.5m) to match specific rack cable management setups.
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