In the past years, we have talked a lot about 10G and 40G Ethernet. Now 100G Ethernet is here and familiar to many of us. IHS Infonetics reports that by 2019, 100G Ethernet will make up more than 50 percent of data center optical transceiver transmissions. This makes 100G transceivers very popular in the transceiver market. Generally, 100G transceivers include CFP/CFP2/CFP4, CXP and QSFP28 transceivers. Among them, the QSFP28 transceiver is the primary 100G transceiver for now and future. Here we will have a comprehensive introduction to QSFP28 transceivers.
We know QSFP+ is specified by a multi-source agreement (MSA) under the auspices of the Small Form Factor Committee. QSFP28 has the same package form factor and transmission lane number as QSFP+. The difference is QSFP28 can support up to 28G per lane, much high than the 10G per lane of QSFP+. QSFP28 transceivers use an MPO/MTP(12 fiber) cable connector and the pinout is as same as the QSFP+ 40G interface. Their cabling type is the same as 40G QSFP+ transceivers and their pinouts are also the same. So switch vendors can provide high density 40G/100G dual mode ports instead of a soup of different port sizes, exactly like the dual mode SFP/SFP+ 1G/10G ports we have now.
The QSFP28 transceiver module was first invented in 2013. With years of developing, there are various QSFP28 transceivers that can support different standards and applications. The followings are the commonly used types in 100G data center:
100Gbase-SR4 QSFP28 Transceiver
As most data centers rely largely on multi-mode fibers, IEEE standard for QSFP28 transceivers that supports short distance over multi-mode was firstly published, which is 100GBase-SR4. 100Gbase-SR4 QSFP28 transceivers have MTP interfaces and can support 100G transmission up to 70m over OM3 and 100m over OM4.
For long distance transmission, the IEEE standard 100Gbase-LR4 is being applied in QSFP28 transceivers. Unlike 100Gbase-SR4 QSFP28 transceivers, 100Gbase-LR4 QSFP28 transceivers use the WDM technologies for four 25G lanes transmission. The four 25G optical signals are being transmitted over four different wavelengths. This kind of 100G transceiver has a duplex LC interface for 100G dual-way transmission and can support transmission up to 10km over single-mode fiber.
100Gbase-PSM4 QSFP28 MSA Transceiver
As mentioned above, 100Gbase-LR4 QSFP28 transceivers can support transmission distance of 10km, which overkills many applications. Thus, MSA published 100Gbase-PSM4 standard to support a transmission distance up to 500m over single-mode multi-fibers. The 100Gbase-PSM4 QSFP28 MSA transceiver has an MTP interface.
100Gbase-CWDM4 QSFP28 MSA Transceiver
MSA also published 100Gbase-CWDM4 standard for QSFP28 over single-mode up to 2km through duplex LC interface. 100Gbase-CWDM4 QSFP28 MSA transceivers also use WDM technologies But the transmission distance is shorter and the cost is much lower than 100Gbase-LR4 QSFP28 transceivers.
Except the above mentioned commonly used QSFP28 fiber optic transceivers, QSFP28 DACs are also being provided in the market to further decrease the costing of 100G connections over short distance. There are mainly two types of QSFP28 direct attach cables: QSFP28 to QSFP28 DAC and QSFP28 to 4×SFP28 DAC. The former is length of copper cable terminated with a QSFP28 connector on each end. The latter is a length of breakout cable with one end terminated with QSFP28 connector and the other terminated with four SFP28 modules. QSFP28 to SFP28 DAC can achieve the 25G to 100G transmission. The length of QSFP28 DAC is usually up to 5 meters which can cover a wide range of short connections in data center.
QSFP28 transceivers are suggested methods for upgrading to 100G network. The above mentioned are the most popular 100G QSFP28 transceivers which are all available for same day shipping in FS.COM. The following table listed part of them for your reference. Kindly contact firstname.lastname@example.org for more details.
|100G QSFP28 Transceiver||Interface||Fiber Type||Distance||Standards|
|100Gbase-SR4 QSFP28 transceiver||MTP||Multimode||70m (OM3); 100m (OM4)||IEEE|
|100Gbase-LR4 QSFP28 transceiver||LC Duplex||Single-mode||10km||IEEE|
|100Gbase-PSM4 QSFP28 MSA transceiver||MTP||Single-mode||500m||MSA|
|100Gbase-CWDM4 QSFP28 MSA transceiver||LC Duplex||Single-mode||2km||MSA|