DAC Cables for 10G and 40G Ethernet Network

With the fast growing of local fiber communication network over the past few decades, people are longing for cables which can provide not only high speed, but also high performance. Thus, vendors around the world are focusing on designing such cables and direct attach cables (DAC) has been proven to be one of the best and cost-effective solutions to satisfy this demand. Today’s article will introduce 10G and 40G DAC cables.

 

A direct attach cable is a kind of optical transceiver assembly with the connector modules permanently attached to either end. It is designed to use the same port as the optical transceiver, but compared to real optical modules, the connector modules at both ends are without expensive optical lasers. Thus, DAC is much cheaper and has lower power consumption than the regular optics. It is popular in the network industry and widely used in storage areas network, data center, and high-performance computing connectivity, etc.

 

With different demands for DAC cables, DAC is being required to be improved and provide more possibilities to satisfy various application environments. Here will introduce two commonly used DACs for your reference.

 

Small Form-Factor Pluggable Plus Transceiver (SFP+) DAC, also known as Twinax cables, uses the inexpensive copper twinaxial cable with SFP+ modules on both sides, which is also based on SFP+ MSA (multi-source agreement), providing 10 Gigabit Ethernet connectivity between devices. SFP+ DAC cable has a fixed-length cable, typically 1 to 7 m (passive cables) or up to 15 m (active cables) in length and is ideal for high-density, in-rack 10Gbps connections between servers and switches with its low cost, low power consumption and low latency. It can not only provide better cable management for high-density deployments, but also enhance electrical characteristics for the most reliable signal transmission. Generally speaking, 10G SFP+ DAC cables can be classified into 10G SFP+ passive copper cable (PCC), 10G SFP+ active copper cable (ACC) and 10G SFP+ active optical cable (AOC). Here is a Cisco compatible SFP-H10GB-CU1-5M 10G SFP+ DAC.

 

Since 1G and 10G are no longer capable of satisfying the increasing bandwidth needs, migration to 40G becomes an imperative and spontaneous alternation to cope with the trend of higher network speeds and greater scalability. And 40G QSFP+ DAC is an ideal solution to support 40G applications.

 

40G QSFP+ DAC transmits 40GbE over short distances of parallel coaxial copper cabling, accomplished using a special cabling assembly with four lanes of coaxial cabling (eight pairs). It is designed to meet high performance computing application needs for high density cabling interconnect system capable of delivering an aggregate data bandwidth of 40Gbps. 40G QSFP+ DAC is a cost-effective solution for 40G LAN, HPC and SAN applications. The three common 40G QSFP+ DACs are 40G QSFP+ to QSFP+ DAC, 40G QSFP+ to 4 SFP+ DAC and 40G QSFP+ to 4 XFP DAC. For example, QSFP+ to QSFP+ DAC consists of a cable assembly that connects two QSFP+ modules respectively at each end of the cable. This kind of cable is usually applied in rather short distances and provides an efficient way to establish a 40G link between QSFP+ ports of QSFP+ switches with less cost. The following image is a Cisco QSFP-H40G-CU1M compatible 40G QSFP+ DAC.

 

DAC cable has received great attention and is popular in the market. The main reason is its lower price compared with regular optics. Another reason is that DAC cables are cost-effective, especially in short distance (< 5 m). This post has provided some basic information about DAC cables and some choices for DACs which are available for different Ethernet network. Besides the choices mentioned above for DACs, a variety of high speed interconnect DAC assemblies including 10G SFP+ cables, 40G QSFP cables and 120G XFP cables, which can satisfy the demands from 10G to 100G interconnection, are in stock in FS.COM. All of these DAC cables can meet the ever growing need to cost-effectively deliver more bandwidth, and can be customized to meet different requirements.