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100G QSFP28 Overview

As 100G services continue to expand in various network applications, this article provides a complete overview of the QSFP28, the most popular form of 100G optical transceiver on the market.


Definition


The 100G QSFP28 optical transceiver is designed primarily for 100G Ethernet services. In terms of physical dimensions, it is identical to the 40G QSFP+ and just like the 40G QSFP+ uses four 10Gbps lanes, the 100G QSFP28 also uses four lanes but at 28Gbps each (hence the 28 in the name). When compared to previous generation 100G optical transceivers like the CFP/CFP2/CFP4, the QSFP28 offers much better port density due to its smaller footprint, consumes less power and comes at a much lower cost per bit.


Key Standards


The 100G QSFP28 optics on the market today are all defined by IEEE and MSA (Multi Source Agreement). The IEEE defines mainly three variants being the SR4 for short reach (100m), the LR4 for long reach (10km), and the ER4 for extended reach (40km). The SR4 and the LR4 are the most popular versions based on the IEEE definition but neither is seen as a perfect fit for the data center application with the SR4 reach being too limited and the LR4 being too expensive. This is why the MSA introduced the PSM4 and the CWDM4 versions of the QSFP28 optics.


Various Options


The following table summarizes the key characteristics for the different QSFP28 optics:

QSFP28

SR4

LR4

PSM4

CWDM4

ER4

Standard

IEEE 802.3

IEEE 802.3

MSA

MSA

IEEE 802.3

Connector

MTP/MPO-12

LC Duplex

MTP/MPO-12

LC Duplex

LC Duplex

Fiber

MMF

SMF

SMF

SMF

SMF

Wavelength

850nm

1295.56-1309.14nm

1310nm

1270-1331nm

1295.56-1309.14nm

Reach

70/100m

10km

500m

2km

40km

Applications


As the cost of the 100G QSFP28 optics have been dropping over the last few years, the range of applications has been widening and currently includes:

  • 100G Ethernet links

  • Data Center interconnects

  • Enterprise networks

  • 100G transport links

Each of these applications has different requirements particularly from a transmission distance perspective and this will be a key determining factor when selecting which type of QSFP28 you need for your application.


GigOptics - Your Supplier for 100G QSFP28


At Gigoptics, we offer a wide range of optical transceivers including all types of QSFP28 100G; all tested to ensure quality and reliability. For more information, contact us at info@gigoptics.com.

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