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14 Mar 2016

40 Gigabit Ethernet era is already upon us and makes a contribution to satisfying the increasing demands of higher throughputs and bandwidth. The 40-Gbps Ethernet transfers data at a rate of 40 gigabits per second over Ethernet. The biggest market for 40G Ethernet (40GbE) is in data center for interconnection links with servers and storage area networks. How to deploy 40G Ethernet? This article will introduce some information related to 40G cabling and transceivers options.

Cables for 40 Gigabit Ethernet

40G cables can provide inexpensive and reliable 40G speed connections using either copper cables with distances reaching up to 30ft (~10 meters length) or active optical cables reaching even 300ft(100 meters). Cables can be divided into different types according to different criteria. There are generally two types: fiber and copper cables.

  • Fiber Cables: active optical cable (AOC) assemblies were invented to replace copper technology in data centers and high performance computing (HPC) applications. The 40G QSFP+ AOC is a parallel 40Gbps quad small form factor pluggable (QSFP+) active optical cable, which supplies higher port density and total system cost. The QSFP+ optical modules provide four full-duplex independent transmit and receive channels, each are able of 10Gbps operation 40Gbps aggregate bandwidth of at least 100m multimode fiber.
  • Copper Cables: QSFP+ to QSFP+ copper cable and QSFP+ to 4SFP+ breakout copper cable are the two common types of QSFP+ cables. QSFP+ to QSFP+ copper cables are hot-removable and hot-insertable. A cable consists of a cable assembly that connects directly into two QSFP+ modules, one at each end of the cable. QSFP+ to 4 SFP+ breakout copper cable is with one QSFP+ on one end and four SFP+ on the other end. It allows a 40G Ethernet port to be used as four independent 10G ports thus providing increased density while permitting backward compatibility and a phased upgrade of equipment. QFX-QSFP-DAC-1M
40G Optical Transceivers Types

40G optical transceivers, compliant to the IEEE standards mainly include CFP and QSFP (Quad Small Form-factor Pluggable). CFP stands for C form-factor pluggable and it is a multi-source agreement to produce a common form-factor for the transmission high-speed digital signals. Nowadays, QSFP is more favored than CFP, and it mainly has the following three types:

  • 40GBASE-SR4 It reaches 40-Gbps Ethernet over four short-range multimode fiber optic cables and supports link lengths of 100m and 150m respectively on laser-optimized OM3 and OM4 multimode fiber cables. In this process, the multimode fiber uses parallel-optics transmission instead of serial transmission due to the 850nm vertical-cavity surface-emitting laser (VCSEL) modulation limits. Parallel-optics transmission uses a parallel optical interface where data is simultaneously transmitted and received over multiple fibers and the interfaces are 4x10G channels on four fibers per direction.
  • 40GBASE-LR4 It reaches 40-Gbps Ethernet over four wavelengths carried by a single long-distance singlemode fiber optic cable and supports link lengths of up to 10 km over single-mode fiber with duplex LC connectors. It operates at a wavelength of 1310 nm. The 40 Gigabit Ethernet signal is carried over four wavelengths with 10G on each wave. It is designed to use in switches, routers and data center equipment where it provides higher density and lower cost when compared with standard SFP+ modules.
  • 40GBASE-CR4 It is a direct attach cable segment with the QSFP+ modules attached to each end of the cable. It reaches 40-Gbps Ethernet over four short-range twinaxial copper cables bundled as a single cable and supports link lengths of up to 10 km over a standard pair of G.652 single-mode fiber with duplex LC connectors. The QSFP+ modules are plugged into the QSFP+ ports on the switch or computer interface. Before you choose to use the 40GBASE-CR4 , please make sure the QSFP+ modules on the cable support the QSFP+ port on your switch or computer interface.

As the main fiber optical manufacturer in China, Fiberstore provides a wide range of 40G cables and optical transceivers, such as Cisco QSFP-H40G-CU5M copper cable, Juniper JNP-QSFP-40G-LR4 QSFP+ transceivers, etc. All our cables can meet the ever increasing need to cost-effectively deliver more bandwidth, and can be customized to meet different requirements.


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