Direct Attach Cable Assemblies for Data Center Interconnection

As is know to all, direct attach cable assemblies include two main types: direct attach copper cable and active optical cable. They are mainly used as media to support high transfer rates between servers, switches and storage devices intra rack or inter rack in a data center. As the direct attach cable assemblies have the same port with an optical transceiver, but with significant cost savings and power savings in short reach applications, they are becoming more and more popular with data center operators.

Types of Direct Attach Cable Assemblies

According to the connectors attached to each end of the fiber cable, the direct attach cable assemblies can be terminated with transceiver-style plugs, such as SFP+ (enhanced small form-factor pluggable) and QSFP+ (quad small form-factor pluggable). With the same ports as the transceiver optics, they can support Ethernet, Infiniband or Fibre channel but with independent protocol. In general, direct attach cable assemblies are divided into three families—direct attach passive copper cable, direct attach active copper cable and active optical cable.

• Direct Attach Passive Copper Cable Without active circuitry component, the direct attach passive copper cable can achieve interconnections up to 7 m at 10 Gbps or 40 Gbps with low power.
• Direct Attach Active Copper Cable The active copper cable is designed in the same cable type as the passive one, but incorporates active component to boost/receive signal that requires more power. It can reach up to 15 m at 10Gbps or 40 Gbps.
• Active Optical Cable Designed in optical fiber type, the AOC incorporates active electrical and optical components, which can achieve longer distance than the copper assemblies. In general, it can reach more than 100 m via multimode fiber.

In addition, with the fan-out technology, both direct attach copper cable and active optical cable can be designed as breakout direct attach cable assemblies, e.g. QSFP+ to SFP+ cable, which can better satisfy the demands on network migration.

Direct Attach Cable Assemblies Use Case

The direct attach cable assemblies are ideal choices for short-reach direct connection application. Generally, they are used in the EDA (Equipment Distribution Area) where cabinets and racks house end equipment (servers) and where horizontal cabling from the HDA (Horizontal Distribution Area) is terminated at patch panels, as shown in the following picture:

For interconnection in racks and between rows of racks, the direct attach cable assemblies are used to connect server to switch, storage to switch or switch to switch. Depending on different interconnect application and distance requirement, the direct attach passive or active copper cable, active optical cable or breakout direct attach cable assemblies with various length options can be used.

As 10G network is widely deployed in today’s data center, 10G SFP+ DACs (e.g. SFP-H10GB-ACU10M) are commonly used in interconnect application below 15 m, e.g. server to switch or storage to switch interconnection in the same rack. And now 25 GbE is popular and recommended to replace the 10G network in the coming future. The 25G direct attach cable assemblies, such as SFP28 DACs, are already available in the market. For 40GbE, 40G QSFP+ DACs and AOCs are used, the former is usually used for short-interconnection below 15 m while the latter is used for longer interconnect application that over 15 m but less than 100 m. Of course, higher speed and more bandwidth are needed for spine switches. Thus, 100G DACs, like QSFP28 DACs are used in this case.

FS.COM Direct Attach Cable Assemblies Solution

FS.COM offers a wide range of direct attach cable assemblies including both DACs and AOCs which cover data rates of 10 G, 25 G, 40 G, 100 G and 120 G. Each of them are tested to ensure 100% compatible with the major brands. Most popular model of the assemblies are with ready stock. Moreover, OEM is available according to your unique requirement.