DAC High-Speed ​​Cable SFP

DAC (Direct Attach Copper) SFP cables are high-speed, factory-terminated twinax copper cables designed for short-range, low-latency connections between network devices, available in passive and active versions.

Overview

A DAC SFP cable is a twinax copper cable with SFP or SFP+ connectors permanently attached at both ends, enabling direct connection between switches, servers, or storage devices without separate transceivers . These cables are plug-and-play, cost-effective, and ideal for short-distance, high-speed networking applications.

Types of DAC Cables

1. Passive DAC
   • Contains no electronics; relies on copper properties for signal transmission.
   • Typical reach: 1–7 meters depending on cable gauge and application .
   • Advantages: Lowest cost, minimal power consumption (<0.15W), low latency.
   • Commonly used for in-rack connections in data centers .
2. Active DAC
   • Includes signal conditioning electronics (retimers or redrivers) to maintain signal integrity over longer distances.
   • Typical reach: 5–15 meters for copper; can extend further with optical variants .
   • Slightly higher cost and power consumption (<1W per cable).
   • Suitable for inter-rack connections or high-density deployments requiring flexible cabling .

Performance and Specifications

• Data Rates: DAC cables support a wide range of speeds, including 10Gbps, 25Gbps, 40Gbps, 50Gbps, 100Gbps, 200Gbps, 400Gbps, 800Gbps, and 1.6Tbps depending on the cable type and form factor .
• Form Factors: SFP, SFP+, QSFP, and OSFP modules are available, with single or double density options .
• Cable Lengths: Typically 0.5m to 15m for copper DACs; active optical cables can reach up to 100m at 10Gbps .
• Construction: Shielded twinax copper with varying gauges (24–30 AWG) and optional low-smoke, zero-halogen jackets for data center safety .

Deployment Considerations

• Compatibility: Ensure the DAC cable matches the SFP/SFP+ port type and revision of your network devices .
• Bend Radius: Maintain a minimum bend radius of 4x the cable diameter (~1 inch) to avoid damage .
• Cost and Power: Passive DACs are cheaper and consume less power, while active DACs provide longer reach and better signal quality.
• Use Cases: Ideal for short-range, high-speed connections within racks or between adjacent racks in data centers, offering low latency and high reliability .

Summary

DAC SFP cables provide a reliable, low-latency, and cost-effective solution for high-speed networking over short distances. Choosing between passive and active DACs depends on the required reach, power budget, and deployment density. They are widely used in modern data centers for connecting servers, switches, and storage arrays efficiently.