With 40 Gigabit Ethernet commonly deployed in most data centers, it is very essential for the data center managers to employ the suitable 40G devices like 40G QSFP+ transceivers. Nowadays, various 40G transceivers are available on the market, but mainly there are two interfaces adopted by 40G QSFP+ transceivers—MTP/MPO and LC. What’s the difference between these two interface types? This article will have an analysis of the 40G QSFP+ transceivers with MTP/MPO interface and 40G QSFP+ transceivers with LC interface.
Generally, the 40G QSFP+ transceivers with LC interface are used for long distance transmission over single-mode fiber (SMF), and QSFP+ transceivers with MTP/MPO interface are utilized for short distance transmission over multimode fiber (MMF). However, for some 40G transceivers with MTP/MPO interface, such as 40GBASE-PLRL4, and 40GBASE-PLR4, they can support long distance transmission over SMF.
40G QSFP+ transceivers with LC interface—In the transmit side, 4-channel 10G serial data streams are passed to laser drivers. The laser drivers control directly modulated lasers (DML) with wavelengths. Then the output of the four DMLs are optically multiplexed to a SMF through an industry-standard LC connector, combining as 40G optical signal. In the receive side, the 40G optical signals are demultiplexed into 4 individual 10G channels with different wavelength. Each wavelength light is collected by a discrete photo diode, and then outputted as electric data after amplified by a TIA. In this process, a 4-wavelength CWDM multiplexer and demultiplexer is used over a pair of single-mode fibers.
40G QSFP+ transceivers with MTP/MPO interface—In the transmit side, the transmitter converts parallel electrical input signals into parallel optical signals through the use of a laser array. Then the parallel optical signals are transmitted parallelly through the multimode fiber ribbon. In the receive side, the receiver converts parallel optical input signals via a photo detector array into parallel electrical output signals.
Note: there are some 40G transceivers with MTP/MPO interface working over SMF as mentioned above. For this kind of PSM (a parallel single-mode optical transceiver with an MTP/MPO fiber ribbon connector) QSFP+, it offers 4 independent transmit and receive channels, each capable of 10G operation for an aggregate data rate of 40G over SMF. That is to say, 8 single-mode fibers are used to achieve parallel transmission.
For the 40G QSFP+ transceivers with LC interface, they cannot be split into 4x10G as they use 4 wavelengths on a pair of single-mode fibers and do not lend themselves to “splitting” into 4 pairs without substantial complexity to split out the wavelengths. For the 40G QSFP+ transceivers with MTP/MPO interface, they can be used in 4x10G connectivity via an external 12-fiber parallel to 2-fiber duplex breakout cable, which connects the 40G module to four 10G optical interfaces.
As a professional manufacturer and supplier in optical communication industry, FS.COM provides a series of 40G transceivers to meet various network demands. The following table lists the generic ones. Besides the generic ones, the 40G transceivers compatible with other brands, such as Cisco, Juniper are also available. Most of them are in stock now and can be shipped the same day after order.
|Model||Interface Type||Cable Type||Max Cable Distance|
|40GBASE-CSR4||MTP/MPO||MMF||400 m over OM4 MMF|
|40GBASE-SR4||MTP/MPO||MMF||150 m over OM4 MMF|
|40GBASE-LR4||LC duplex||SMF||10 km|
|40GBASE-LR4L||LC duplex||SMF||2 km|
|40GBASE-ER4||LC duplex||SMF||40 km|
|40GBASE-LX4||LC duplex||MMF/SMF||OM3/OM4 MMF: 150 m, SMF: 2 km|
|40GBASE-SR BiDi||LC duplex||MMF||150m@OM4/100m@OM3/30m@OM2|
|40GBASE-LR4 CFP||SC duplex||SMF||10 km|