How to Choose the 40G Transceivers

With the economics-driven growth of global regional and local fiber communication network over the past few decades, the IEEE 802.3 ba 40-Gbps Ethernet standard was published in June, 2010. In order to meet the data transmission needs in the market, a high-performance and flexible implementation of the IEEE 802.32012 for 40-Gbps Ethernet - 40G transceivers are developed and widely used. The 40-Gbps Ethernet transfers data at a rate of 40 gigabits per second over Ethernet.

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. The 40-Gigabit CFP transceiver module is prepared for use within 40-Gbps Ethernet links over single mode fiber. While the 40-Gigabit QSFP transceiver module is a hot-swappable, parallel fiber-optical module with four independent optical transmit and receive channels. These channels can terminate in another 40-Gigabit QSFP transceiver, or the channels can be broken out to four separate 10-Gigabit SFP+ transceivers. It is an industry format jointly developed and supported by many network component vendors, allowing data rates from 4x10 Gbit/s.

As the 40-Gigabit QSFP transceivers are used to interface networking hardware to a fiber optic cable, the choice of them depends on many factors, like the transport media, the connector type, transmission distance, wavelength, etc. Today, let’s mainly discuss on how to choose the proper 40-Gigabit QSFP transceivers according to the media system. According to the IEEE 802.3 ba 40Gb/s Ethernet standard, commonly used 40-Gbps Ethernet media systems include the following:
● 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. Multiplexing and demultiplexing of the four wavelengths are managed within the device. 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.

Fiberstore provides various types of 40-Gigabit QSFP transceivers including single-mode and multi-mode with different channels and wavelengths. In order to achieve a fast and successful selection of the proper transceivers, transport media is an important factor in choosing the 40-Gigabit QSFP transceivers.