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What is a DAC Cable?

Network cabling has changed dramatically over the years, driven by the need for higher speed fiber optic cables. Cat5e copper and 1000BASE-T have dominated data center interconnect applications for many years. However, SFP cables, a form of high-speed cable with pluggable connectors on both ends, are the new favorite for lower cost and lower power consumption. This direct connection line can be divided into DAC line and AOC line. DAC cables are the most basic form of high-speed direct-attach cables. So what is a DAC cable?

What is a DAC cable: Understanding DAC cables

What is a DAC cable, a DAC cable is a fixed high-speed copper cable assembly. It consists of a shielded twin-core copper cable with pluggable connectors on both ends, ranging in gauge from 24 to 30AWG: the longer the distance, the higher the AWG rating should be. It can be used to connect a switch to a router or server for short-distance transmission. Additionally, DAC cables typically come in several different categories: SFP+DAC, XFPDAC, QSFPDAC, etc.

Generally speaking, according to the structure, DAC cables can be divided into two types: passive DAC cables and active DAC cables. Passive DAC cables have no electrical components built into the cable assembly. Therefore, its minimum power consumption does not exceed 0.15w, and generally the short distance can reach 7m. Active DAC cables have signal amplification and equalizer built into the cable assembly. Therefore, it allows a slightly longer transmission distance up to 15m and ensures better transmission quality. And its price is higher, and it consumes more power at around 0.5-1w.

An SFP28 DAC cable is a type of high-speed, direct-attach copper cable that is commonly used for short-distance data center connections, providing a cost-effective alternative to traditional optical transceivers.

Types of DAC Cables:

  • Passive DAC: Utilizes standard copper cables and doesn't require external power, offering a cost-effective option for short-range connections.

  • Active DAC: Includes active electronic components to boost signal strength, enabling longer reach compared to passive DACs.

What is a DAC cable: the advantages of a DAC cable

Knowing what is a DAC cable, what are the advantages of a DAC cable?

Lower power consumption: Compared with optical transceiver modules, DAC cables, especially passive copper cables, consume less power.

Lower price: DAC cables cost less because they do not require a patch panel or additional cables when connected to equipment as optical transceiver modules.

Easier Deployment: DAC cables have only one component to interconnect. However, to connect more devices, optical modules must match each other. Additionally, installers can conveniently save on DAC cables, eliminating the need to clean and inspect fibers before plugging them in.

A data center transceiver is a critical networking component that enables the transmission and reception of data between network devices in a data center environment.

  • High Speed: Supports 10 Gigabit Ethernet (10GbE), 25GbE, 40GbE, and even 100GbE data rates depending on the specific type.

  • Hot-swappable: Enables easy installation and removal without network downtime.

  • Compact and Lightweight: Saves space and simplifies cable management.

  • Cost-effective: Passive DACs are generally cheaper than transceivers and fiber optic cables for short distances.

  • Limited Reach: Typically limited to 3-10 meters for passive DACs, and up to 25-30 meters for active DACs.

What is a DAC cable: Where to use a DAC cable?

As a professional company dealing with China optical transceiver, we remind you that DAC cables used in various applications in data centers can extend the life of switch hardware without requiring changes to existing infrastructure. In general, this direct attach copper cable is suitable for the following applications: ToR/adjacent rack, both passive and active DAC cables are suitable for shorter ToR or adjacent racks. Middle of Row, active DAC cables are probably the best solution in this application as long as the distance does not exceed 15m. End of Row, as long as the distance is right, DAC cables are well suited for end of row architectures.

  • Intra-rack and inter-rack connections within data centers: Connecting switches, servers, and storage devices within close proximity.

  • Top-of-rack (ToR) switching: Connecting servers directly to switches at the top of the rack for high-performance networking.

  • High-performance computing (HPC) clusters: Interconnecting HPC nodes for parallel processing tasks requiring fast data exchange.

  • Enterprise network backbones: Short-range connections within network equipment cabinets.

Choosing the Right DAC Cable:

Selecting the optimal DAC cable depends on several factors:

  • Data Rate: Match the cable's speed to your network requirements (10GbE, 25GbE, etc.).

  • Reach: Choose a cable length that meets your connection distance needs.

  • Connector Type: Ensure compatibility with your network equipment ports (SFP+, QSFP+, etc.).

  • Passive vs. Active: Consider cost, reach requirements, and power availability.

  • Cost and Brand: Balance functionality with budget and opt for reputable brands.

Additional Considerations:

  • Heat Dissipation: DAC cables generate more heat than fiber optic cables, especially active ones. Ensure proper ventilation in high-density environments.

  • Future Needs: Consider potential upgrades and choose a cable length that accommodates future growth.

Beyond these core aspects, tailor your choice based on specific applications:

  • Data Center: Prioritize cost-effective passive DACs for short intra-rack links.

  • HPC: Focus on high-performance cables with low latency and error-free transmission.

  • Enterprise Networks: Balance cost and performance based on specific needs and budget constraints.

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