# QSFP-DD and QSFP28 Cable Comparison and Selection Guide
## Introduction to QSFP-DD and QSFP28 Cables
In the world of high-speed data transmission, QSFP-DD and QSFP28 cables play crucial roles in modern networking infrastructure. These form factors represent significant advancements in connectivity solutions, offering different capabilities to meet various networking requirements.
## Understanding QSFP28 Cables
QSFP28 (Quad Small Form-factor Pluggable 28) cables have been the industry standard for 100G Ethernet and InfiniBand applications. The “28” denotes its support for 28 Gbps per lane, enabling 100G connectivity through four lanes.
Keyword: qsfp-dd qsfp28 cable
Key Features of QSFP28:
- Supports data rates up to 100Gbps
- Backward compatible with QSFP+ (40G) ports
- Available in active optical cables (AOC) and direct attach copper (DAC) variants
- Commonly used in data centers for spine-leaf architectures
## Exploring QSFP-DD Cables
QSFP-DD (Quad Small Form-factor Pluggable Double Density) represents the next generation of high-density, high-speed connectivity. It doubles the lane count of QSFP28 while maintaining the same port size.
Key Features of QSFP-DD:
- Supports data rates up to 400Gbps (8x50G)
- Maintains backward compatibility with QSFP28 and QSFP+
- Offers higher port density than QSFP28
- Designed for next-generation data center applications
## Comparison Between QSFP-DD and QSFP28 Cables
1. Data Rate Capabilities
QSFP28 supports up to 100Gbps (4x25G or 4x28G), while QSFP-DD supports up to 400Gbps (8x50G). This makes QSFP-DD ideal for bandwidth-intensive applications.
2. Physical Dimensions
Both form factors have similar width, but QSFP-DD is slightly longer to accommodate the additional electrical contacts. The port size remains compatible, allowing QSFP-DD ports to accept QSFP28 modules.
3. Power Consumption
QSFP-DD modules typically consume more power (up to 12W) compared to QSFP28 (typically 3.5W-5W). This is an important consideration for data center power budgets.
4. Application Scenarios
QSFP28 remains the dominant choice for 100G deployments, while QSFP-DD is gaining traction for 200G and 400G applications, particularly in hyperscale data centers.
## Selection Guide: Choosing Between QSFP-DD and QSFP28
When to Choose QSFP28:
- For existing 100G network infrastructure
- When cost-effectiveness is a priority
- For deployments where power efficiency is critical
- In environments with established QSFP28 ecosystem
When to Choose QSFP-DD:
- For future-proofing network infrastructure
- When planning 200G or 400G deployments
- In high-density environments where space is limited
- For hyperscale data center applications
