1m 40G QSFP+ Direct Attach Copper Cable (DAC): Optimized for Top-of-Rack (ToR)
The 1m 40G QSFP+ to QSFP+ Direct Attach Copper Cable (DAC) is an ultra-short reach passive Twinax cable designed for 40Gbps Ethernet interconnections within a single rack. This 1-meter cable provides a near-zero latency path and zero power consumption, making it the most energy-efficient and cost-effective alternative to 40G transceivers for Top-of-Rack (ToR) switch-to-switch or switch-to-server stacking.
Technical Specifications & Comparison
At the 1-meter length, cable flexibility (AWG) and signal integrity at high frequencies are the primary differentiators.
| Feature | 40G QSFP+ Passive DAC (1m) | 40G QSFP+ AOC (1m) |
| Transmission Media | 30AWG Twinax Copper | 850nm Multimode Fiber |
| Power Consumption | 0W (Passive) | ~1.5W per end |
| Latency | Lowest (No O-E Conversion) | Micro-delays (Signal Conversion) |
| Durability | High (Robust Copper) | Moderate (Fragile Fiber) |
| Bending Radius | 25mm – 30mm | 30mm |
| MTBF (Reliability) | Superior (No active lasers) | High |
DAC Cable Using in Intra-Rack and Inter-Rack Connectivity
The direct attach copper cable is commonly using in the short distance of data transmission, so the length of the DAC cable are usually 1m/2m/3m/5m/7m. For the short distance, 40G DAC cable is widely used for establishing connections within the same rack or between adjacent racks in data centers. This intra-rack and inter-rack connectivity is essential for linking networking equipment, servers, and storage devices, creating a cohesive and high-performance infrastructure within the data center environment.
Low Latency While Using the DAC Cable
DAC copper cable are copper wire so there are no delays in switching copper signals to optical and then back to copper. Direct attach copper cables have the lowest latency of all short-reach cables (<8ft /3m). For services such as financial trading, edge computing, AI, AR/VR gaming, enterprise video conferencing, any reduction in latency is an advantage. DAC cables offer low-latency connectivity, ensuring that data travels quickly and efficiently between interconnected devices.
High Speed 40G DAC Cable Features
lHot-plug swappable
l3X Port Density over SFP / SFP+
lOptimized NEXT & Return Loss
lLow cost and low power solution compared to fiber optical cable
lCompliant with QSFP+ MSA and SFF-8436
lCompliant with IEEE 802.3ba/ Infiniband QDR specifications
lEnhanced EMI/EMC performance
lSupports serial ID functionality thru EEPROM
lPassive cable assembly supports distances up to 7 meters
l30AWG to 24AWG cable sizes available
lRoHS compliant and Halogen-Free option available
QSFP+ Direct Attach Cable Application
lSwitches / Routers / HBAs/SAN, NIC cards
lServer & Storage Devices
lData Center Networking
lHigh Performance Compute
lFiber Channel
lInfiniBand QDR/DDR
l10Gbs/40Gbs Ethernet
The 1m 40G DAC is the go-to solution for Switch Stacking, HCI (Hyper-Converged Infrastructure) nodes, and High-Performance Computing (HPC) clusters. It is designed to withstand the tight bends required in 1U and 2U rack deployments. Explore our High-Density Data Center Solutions for optimized intra-rack cabling strategies.
Compatible with Different Switches
This DAC Cable feature with 40G QSFP fiber transceiver, which could be compatible with different switches brands, likes Cisco, Juniper, H3C, Huawei, Alcatel, Allied Telesis, Zyxel, Brocade, Mikrotik, Extreme, Blade, D-linnk Netgear, Finisar, ZTE, Linksys, SMC, Ruijie, Avaya, 3com, Enterasys, Redeback, Planet etc.
Expert Insight: The UnitekFiber Advantage
For 1-meter connections, many people over-engineer by using AOCs. From an application perspective, a 1m DAC is actually more reliable because it has fewer active components to fail. At Op2Link, we focus on the EEPROM handshake—ensuring that when you plug this 1m cable into a Cisco Nexus and an Arista switch, they recognize each other instantly without CLI workarounds.
Solving Your Connectivity Challenges
Every rack environment presents its own set of hurdles, from port-density cooling issues to multi-vendor compatibility headaches. At Op2Link, we don’t just sell cables; we help you design a stable physical layer. If you are unsure whether 30AWG or 26AWG is better for your airflow, or if you need a custom-coded “dual-vendor” cable for a mixed-brand setup, our engineering team is ready to assist.
Let us help you eliminate the guesswork in your next 40G deployment. Consult our
