A Direct Attach Cable (DAC) is a twinaxial copper cable with pre-terminated transceivers on both ends, used for high-speed, short-range data connections between networking devices like switches, routers, and servers. It’s a cost-effective alternative to optical transceivers and cables.
DAC cables are commonly used in data centers and enterprise networks for connecting equipment within or between racks, supporting applications like cloud computing, high-performance computing (HPC), storage area networks (SANs), and server-to-switch connectivity.
DAC cables support a range of speeds, including 10Gbps (SFP+), 25Gbps (SFP28), 40Gbps (QSFP+), 100Gbps (QSFP28), and up to 400Gbps (QSFP-DD), depending on the cable type and network requirements.
DAC cables are typically available in lengths from 0.5 meters to 7 meters. Beyond this range, Active DACs or Active Optical Cables (AOCs) may be recommended for longer distances.
- Passive DAC Cables: No signal amplification, suitable for shorter distances (up to 5-7 meters), lower power consumption, and more cost-effective.
- Active DAC Cables: Include signal conditioning for longer distances (up to 10-15 meters), slightly higher power usage, and better signal integrity over extended lengths.
Most DAC cables are designed to comply with industry standards (e.g., SFP+, QSFP28) and are compatible with major brands like Cisco, Arista, Juniper, and Dell. Always check the compatibility list or consult with your supplier to ensure proper interoperability.
- DAC Cables: Lower cost, lower power consumption, ideal for short distances (up to 7m), but heavier and less flexible.
- AOC Cables: Support longer distances (up to 100m), lighter and more flexible, but more expensive and consume more power.
Yes, DAC cables are versatile and support both Ethernet and InfiniBand protocols, depending on the cable and equipment configuration. Verify the specific protocol requirements before purchasing.
No, DAC cables come with integrated transceivers on both ends, making them plug-and-play and eliminating the need for separate transceivers.
Yes, DAC cables are hot-swappable, meaning they can be connected or disconnected without powering down the equipment, provided the devices support hot-swapping.
Consider the following:
- Speed: Match the cable speed (e.g., 10G, 100G) to your equipment.
- Length: Select a length suitable for your rack setup (0.5m to 7m).
- Form Factor: Ensure compatibility (e.g., SFP+, QSFP28).
- Passive vs. Active: Choose based on distance and signal requirements.
- Brand Compatibility: Confirm interoperability with your devices.
DAC cables, especially passive ones, consume significantly less power (often <0.5W) compared to optical transceivers or AOCs, making them an energy-efficient choice for data centers.
Yes, DAC cables are ideal for high-density setups due to their compact design and ability to handle high-bandwidth connections in confined spaces like server racks.
DAC cables are built with robust copper conductors and shielded connectors, ensuring durability and reliable performance in demanding environments. Proper handling and avoiding excessive bending will extend their lifespan.
- Verify compatibility with your equipment.
- Check for secure connections on both ends.
- Ensure the cable length is within the supported range.
- Test with another port or device to rule out hardware issues.
- Contact your supplier for troubleshooting or replacement if needed.
