# QSFP28-DD Cable Overview and Applications
## Introduction to QSFP28-DD Cables
QSFP28-DD (Quad Small Form-factor Pluggable 28 Double Density) cables represent the next generation of high-speed interconnect solutions designed to meet the growing demands of modern data centers and high-performance computing environments. These cables build upon the successful QSFP28 form factor while doubling the port density and bandwidth capacity.
## Key Features of QSFP28-DD Cables
The QSFP28-DD specification offers several important features:
– Double the density of standard QSFP28 ports
– Support for data rates up to 400Gbps (8x50G PAM4)
– Backward compatibility with QSFP28 and QSFP+ ports
– Improved thermal performance for high-density deployments
– Multiple cable options including direct attach copper (DAC) and active optical cables (AOC)
## Technical Specifications
QSFP28-DD cables adhere to strict technical standards:
Parameter | Specification
Data Rate | Up to 400Gbps (8x50G PAM4)
Connector Type | Double-density 38-pin connector
Cable Types | Passive DAC, Active DAC, AOC
Maximum Length | 3m (passive DAC), 5m (active DAC), 100m+ (AOC)
Power Consumption | Varies by type (typically 1-5W)
## Common Applications
QSFP28-DD cables find use in various high-performance networking scenarios:
### Data Center Interconnects
These cables are ideal for spine-leaf architectures in modern data centers, providing high-bandwidth connections between switches and routers while maintaining port density.
### High-Performance Computing
In HPC environments, QSFP28-DD cables enable fast data transfer between compute nodes and storage systems, crucial for scientific research and AI workloads.
### Cloud Infrastructure
Major cloud providers utilize QSFP28-DD technology to build scalable, high-bandwidth networks that can handle massive amounts of east-west traffic.
## Comparison with Other Form Factors
When compared to alternative solutions, QSFP28-DD offers distinct advantages:
– Higher density than standard QSFP28 (2:1 ratio)
– More cost-effective than OSFP for many applications
– Better thermal characteristics than some competing high-density form factors
– Established ecosystem with multiple vendor support
## Future Outlook
As network bandwidth requirements continue to grow, QSFP28-DD is positioned to serve as an important transitional technology between current 100G/400G deployments and future 800G solutions. Its balance of performance, density, and cost-effectiveness makes it particularly attractive for data center operators looking to maximize their infrastructure investments.
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