As 10G SFP+ direct attach copper twinax cables (DACs) and transceivers become common for top of rack (ToR) applications in the data centre, where small access switches or port extenders connect directly to servers, SFP+ DACs were developed specifically as a cost-effective alternative to optical modules for these short-reach, high-speed interconnects. By incorporating SFP+ DACs into the physical infrastructure, organizations can achieve 10G performance without additional signal processing or conversion. This provides an ideal low power and low latency 10 Gbps server interconnect option for ToR switching deployments. However, what should you pay attention to when deploying SFP+ DACs in your network? Read this article and you will get the answer.
Don’t Exceed Bend Radius of Your SFP+ Cables
The weight of large bundles of SFP+ cables can exert a significant force along the horizontal plane, and specifically on the host port of the active equipment. If the cable emerges from the rear of the connector at too sharp an angle, excess mechanical stress may be transmitted both along the cable and into the circuit board located inside the connector. Excessive side forces exerted by the cable can also misalign the plug in the equipment-mounted receptacle. These forces may degrade performance or even possibly damage the connector and lead to failure. It is important to observe and maintain proper cable bend radius and equally important to provide adequate and secure strain relief on the cable. In order to help maintain proper bend, it is recommended to confirm the American wire gauge (AWG) of your SFP+ cables first. Standard copper SFP+ cables are offered in different wire AWG depending on length. Cables must not be bent below their minimum bend radius, which depends upon cable size as expressed in AWG. The table below summarizes minimum values typically admitted for SFP+ cables sustained bend radiuses.
|AWG Cable Size||Sustained Bend Radius|
|24||1.5 inches (38 mm)|
|26||1.3 inches (33 mm)|
|28||1.0 inches (25 mm)|
|30||0.9 inches (23 mm)|
Calculate the Length of Your SFP+ Cables
When you deploy SFP+ cables within a single 84 in. 45 RU cabinet, conservatively the longest connection will be 7 ft. or 2.1m to reach from the top U to the bottom and approximately 1.5 ft. or 0.45m to route to any port on either end. Example cabinet with 2 top of rack switches and 20 2U servers with dual SFP+ NICs (Network Interface Cards) total of 40 SFP+ cables. Conservatively, longest cable required to reach farthest port is 2.1+2×0.45≈3m. A 3m cable should be adequate to connect any two ports within a cabinet.
Use Cable Management Tools to Bear Your Heavy SFP+ Cables
To help manage the weight of bundled cable and ensure they do not sag over time, a cable manager or strain relief bar should be installed to support SFP+ cables and provide strain relief along the horizontal plane. Strain relief bars facilitate the correct alignment of cable and connector into the port, and help installers observe manufacturer and bend radius requirements of cable close to the connector. The strain relief bars also help keep cables routed clear from spaces directly behind server and switch equipment, reducing thermal resistance through the equipment and promote effective cooling and airflow. Besides, cable ties should be used to bundle the cables together and tie them to the strain relief bars and cable managers. This should be done carefully to ensure the cables are firmly in place and will not move, but not so tight as to deform or stress the cable jacketing.
SFP+ direct attach copper twinax cables offer the smallest 10G form factor and a small overall cable diameter for higher density and optimized rack space in 10G uplinks and 10G Fiber Channel SAN and NAS input/output connections. The use of DAC cable can cost up to three times less than fiber optic solutions, while offering lower latency and consuming up to 50% less power per port than current copper twisted-pair cabling systems. FS.COM provides full series of 10G SFP+ cable, which covers a wide range of applications. Both generic and brand compatible versions are available. All SFP+ cables are 100% tested to ensure the compatible and quality.
|FS PN.||SFP+ Direct Attach Copper Twinax Cable Description|
|21269||0.5m(1.6ft) 10G SFP+ Passive Direct Attach Copper Twinax Cable 30AWG|
|21254||1m(3.3ft) 10G SFP+ Passive Direct Attach Copper Twinax Cable 30AWG|
|39781||1.5m(4.9ft) 10G SFP+ Passive Direct Attach Copper Twinax Cable 30AWG|
|21278||2m(6.6ft) 10G SFP+ Passive Direct Attach Copper Twinax Cable 30AWG|
|48914||2.5m (8.20ft) 10G SFP+ Passive Direct Attach Copper Twinax Cable 30AWG|
|35194||3m(9.8ft) 10G SFP+ Passive Direct Attach Copper Twinax Cable 30AWG|
|30743||7m(23ft) 10G SFP+ Active Direct Attach Copper Twinax Cable 24AWG|
|30778||10m(32.8ft) 10G SFP+ Active Direct Attach Copper Twinax Cable 24AWG|