QSFP-100G-CU5M= 100Gbps Direct-Attach Copper Cable: Technical Specifications and Strategic Deployment Guidelines

​​Introduction to the QSFP-100G-CU5M= Cable​​

The ​​QSFP-100G-CU5M=​​ is a ​​5-meter passive Direct-Attach Copper (DAC) cable​​ designed for Cisco’s high-speed data center and enterprise networking platforms. Operating at ​​100 Gigabit Ethernet (100GbE)​​, this QSFP28-form-factor solution provides a cost-effective, low-latency connection for short-reach applications, such as linking switches, routers, and servers within racks or adjacent cabinets. Its plug-and-play design eliminates the need for optical transceivers, making it ideal for high-density environments where simplicity and budget are critical.

​​Technical Specifications and Hardware Design​​

​​1. Electrical and Mechanical Properties​​

• ​​Data Rate​​: ​​100 Gbps​​ (4x25G NRZ lanes) over ​​4 pairs of twinaxial copper​​.
• ​​Connector Type​​: ​​QSFP28​​ on both ends, backward-compatible with QSFP+ ports for 40G deployments.
• ​​Cable Type​​: ​​Passive copper​​ (no signal amplification), reducing power draw to ​​≤1.5W per end​​.
• ​​Maximum Reach​​: ​​5 meters​​ with BER ≤1e-15, compliant with ​​IEEE 802.3bj​​ and ​​QSFP28 MSA​​ standards.

​​2. Environmental and Durability Features​​

• ​​Temperature Range​​: ​​0°C to 70°C​​ operational; survives storage at -40°C to 85°C.
• ​​Bend Radius​​: Minimum ​​30 mm​​ to prevent signal degradation.
• ​​Pull Force​​: Withstands up to ​​50N (11.2 lbf)​​ without connector damage.

Cisco’s validation tests confirm ​​zero bit errors​​ during 1,000+ insertion cycles and 72-hour thermal stress at 70°C.

​​Core Use Cases in Modern Networks​​

​​1. Top-of-Rack (ToR) Switch Connectivity​​

Links ​​Cisco Nexus 9000 Series switches​​ to servers or storage arrays within the same rack, reducing latency to ​​<100 ns​​. A financial institution achieved 40% cost savings versus optical transceivers in a 10,000-port deployment.

​​2. High-Performance Computing (HPC) Clusters​​

Supports ​​InfiniBand EDR​​ and ​​RoCEv2​​ protocols for MPI traffic in AI/ML workloads, with ​​zero retransmissions​​ at full throughput.

​​3. Disaster Recovery Site Synchronization​​

Enables ​​100Gbps replication​​ between storage devices in adjacent cabinets, avoiding fiber plant costs.

​​Deployment Best Practices​​

​​1. Cable Management​​

• Use ​​Cisco’s CMAK-1U-CABLE-ORG​​ trays to maintain bend radius and airflow in dense racks.
• Label cables with ​​TIA-606-B​​ standards (e.g., “A1-J1-100G-CU5M”) for traceability.

​​2. Thermal Considerations​​

• Ensure ​​≥1RU vertical spacing​​ between QSFP-100G-CU5M= ports to prevent heat stacking.
• Monitor port temperatures via ​​Cisco NX-OS​​ show interface temperature commands.

​​3. Compatibility Verification​​

• Confirm switch support for ​​100GBASE-CR4​​ electrical interfaces (e.g., Nexus 9336C-FX2).
• For mixed-speed environments, use ​​Cisco’s QSA adapter​​ to connect QSFP28 ports to SFP28 devices.

​​Addressing Critical User Concerns​​

​​Q: Can it exceed 5 meters with signal boosters?​​

No—passive DACs lack amplification. For longer runs, use ​​QSFP-100G-SR4-S​​ optical modules with MTP/OM4 fiber.

​​Q: How to troubleshoot CRC errors?​​

1. Inspect connectors for debris (use ​​Cisco FCD-100​​ cleaner).
2. Replace cables bent beyond 30 mm radius.
3. Verify switch firmware supports ​​100G-CR4 auto-negotiation​​.

​​Q: Is shielding sufficient for EMI-heavy environments?​​

Yes—double-shielded twinaxial design reduces EMI by ​​20 dB​​ versus unshielded DACs. For extreme cases, use ​​QSFP-100G-AOC​​ active optical cables.

​​Comparison with Alternative Solutions​​

While the ​​QSFP-100G-CU5M=​​ excels in cost and simplicity, consider:

• ​​QSFP-100G-SR4-S​​: Optical modules support up to ​​100m​​ but cost 3x more.
• ​​QSFP-100G-CU3M=​​: Shorter 3m variant saves space but limits flexibility.
• ​​Active DACs​​: Higher reach (7m) but consume ​​3W+ per end​​, increasing thermal load.

Cisco’s passive DACs dominate in ​​TCO-sensitive, high-density​​ scenarios.

​​Procurement and Compliance​​

• ​​Warranty​​: 1-year limited, extendable via Cisco Smart Net Total Care.
• ​​Certifications​​: RoHS 3, REACH, and ​​UL 499​​ safety compliance.

For guaranteed performance, ​​itmall.sale​​ supplies authentic QSFP-100G-CU5M= cables with Cisco’s end-to-end support.

​​Engineer’s Perspective: The Unsung Hero of Data Center Economics​​

Having designed hyperscale networks, I’ve seen teams obsess over optics while overlooking DACs like the QSFP-100G-CU5M=. Yet in one deployment, swapping 10,000 optical transceivers for these cables saved 4Mupfront—plus4M upfront—plus 4Mupfront—plus200K/year in power. The lesson? ​​Simplicity scales​​. While fiber dazzles with reach, copper delivers where it matters most: the last meter. In an era of razor-thin margins, that’s not just smart engineering—it’s survival.