100G QSFP28 Transceiver Selection Tutorial For Beginer's - Walsun

What is a 100G QSFP28 Transceiver

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The 100G QSFP28 transceiver is a fiber optic communication module used to increase data transmission rates to 100Gbps, typically employing PAM4 modulation technology. It consists of an optical transmitter, optical receiver, module housing, and chipset. This module typically utilizes multimode or single-mode fiber optic cables as transmission media and converts electrical signals to optical signals through electro-optical modulation technology, enabling high-speed data transmission and communication over optical fibers.

100G QSFP28 Four Lambda Transceivers

In transceivers with four lambdas, data transmission is distributed across 4 separate wavelengths. Each lane has its own transmitter and receiver operating at 25Gbps, aggregating to the total data rate of 100Gbps. The SM wavelengths can be further classified to LAN WDM (nm, nm, nm and nm) and CWDM (nm, nm, nm and nm), with the latter offering better cost efficiency due to the wider separation of wavelengths.

Figure 1: Singlemode (SM) QSFP28 4 lambda configuration

The QSFP28 modules that can be offered are:

QSFP28

Datasheet

Max Distance

Connector

PSM4

QSFP-100G-PLR4L

2km

MPO 12

CWDM4

QSFP-100G-CLR4

10km

Duplex LC

LR4

QSFP-100G-LR4

10km

Duplex LC

ER4

QSFP-100G-ER4

40km

Duplex LC

ZR4

QSFP-100G-ZR4

80km

Duplex LC

ZR4+

QSFP-100G-eZR4+

100km

Duplex LC

100G QSFP28 Single Lambda Transceivers

In single lambda transceivers, data transmission occurs over a single optical wavelength, using 1 channel/ lane, allowing higher data rate over a pair of optical fiber. Unlike 4 lambda transceivers, single lambda technology simplifies the design of transceivers with reduced optics, thus reduces power consumption and costs. The single lambda transceiver supports only SM transmission, ranging from 500m (DR1), 2km (FR1) and 10km (LR1).

Figure 2: Singlemode (SM) QSFP28 Single lambda configuration

QSFP28

Datasheet

Max Distance

Connector

DR1

QSFP-100G-DR

500m

Duplex LC

FR1

QSFP-100G-FR

2km

Duplex LC

LR1

QSFP-100G-LR

10km

Duplex LC

CWDM Single Lambda QSFP28 transceiver module is designed for use in 100Gbps Ethernet links over 10km single mode fiber, incorporating one channel optical signal, on either , , , or nm. Typically, they are used in Data Center Environment for connecting 400Gbps Ethernet CWDM wavelengths, and break-out to specified 100Gbps CWDM wavelengths for leaf-spine networks.

CWDM Single Lambda QSFP28 transceiver:

QSFP28

Datasheet

Max Distance

For more 100g qsfp28information, please contact us. We will provide professional answers.

Connector

Wavelength

LR

QSFP-100G-LRCxx

10km

Duplex LC

Please specify xx = 27:nm, 29:nm, 31: nm, 33:nm

DWDM Single Lambda QSFP28 transceiver module is designed for use in C-band DWDM networks with 100GHz ITU Grid spacing for Data Center Interconnectivity. The modules have fixed DWDM wavelengths that are plugged directly into transponders, routers, or switches. In most cases it can achieve 2km without DCM (Dispersion Compensation Module) and EDFA (Erbium-Doped Fiber Amplifier). However, for long and extended distances up to 120km, DCM and EDFA are required to compensate fiber link loss and fiber dispersion. Starview can provide you the complete solution for such requirements.

DWDM Single Lambda QSFP28 transceiver:

How to Select the Best QSFP28 Optics?

The first thing to make sure of before purchasing is the transmission distance you expect the transceivers to reach. Here are a few tips to choose the right QSFP28 transceivers for your 100G deployment based on different transmission distances.

1. Copper DAC Used Inside Racks: 1-5m

QSFP28 DACs are a very cost-effective I/O solution for 100GbE connectivity within 5m. If your 100G deployment is within 5m intra racks, the DACs would be good for you.

2. Multimode Fiber Use Between Switches: 5-100m

For 100G cabling between switches, there are two options to choose from. One is to use QSFP28 AOC for a distance of 3-20 meters. And the other option is to use a QSFP28 SR4 transceiver with 12-fiber MTP OM3/OM4 cable to reach a distance of up to 100m.

3. Single-Mode Fiber Use Between Switches: 100m-2km

For a distance of 100m-2km, there are two recommendations, QSFP28 PSM4 and CWDM4 transceivers. QSFP28 PSM4 can support up to 500m over 12-fiber MTP single-mode fiber cable. QSFP28 CWDM4 transceivers are suitable for 2km over duplex LC single-mode fiber cable.

4. Single-Mode Fiber for Long Span: ≤10km

For long-distance 100GbE deployment, such as connectivity between two buildings, mostly up to 10 km, QSFP28 LR4 with duplex LC single-mode fiber cable is the preferred option defined by IEEE. Some QSFP28 LR4 modules can even reach a maximum distance of 20km.

5. Transmission Distance Exceeds 10 km

The QSFP28 ER4 optical transceiver provides superior performance for 100G Ethernet applications up to 40 km links. It converts 4 input channels of 25Gb/s electrical data to 4 channels of LAN WDM optical signals and then multiplexes them into a single channel for 100Gb/s optical transmission. There are also QSFP28 ZR4 100G module and DWDM PAM4 module for extended long-haul transmission up to 80km.

100G QSFP28 Modules: FAQs

Q: What compatible brands of Walsun QSFP28 modules are available?

A: Walsun offers high-quality 100G QSFP28 transceivers that are compatible with mainstream brands including Cisco, Arista, Juniper, Brocade, Dell, Extreme, HW, H3C, Ciena, Mellanox, IBM, Generic, Walsun, Edge-Core, Palo Alto Networks, Avago, Allied Telesis, Check Point, Chelsio, F5 Networks, etc.

Q: What's the difference between Walsun QSFP-100G-ER4L-S and QSFP-100/112G-ER4 transceiver?

A: QSFP-100G-ER4L-S QSFP28 transceiver module is designed for use in 100GBASE Ethernet throughput up to 40km over single mode LC fiber cable. While the QSFP-100/112G-ER4 QSFP28 is a dual rate optical transceiver, supporting data rate of 103.1Gbps and 112Gbps. It is suitable to be used in various applications, such as 100GBASE Ethernet, telecom, 5G network mid/backhaul.

Q: What's the difference between Walsun QSFP-100G-PSM4-S and QSFP-100G-CWDM4-S?

A: QSFP-100G-CWDM4-S optical transceiver is designed with LC duplex connector, supporting the maximum transmission distance up to 2km. While QSFP-100G-PSM4-S optics is designed with MTP/MPO connector and the maximum transmission distance is 500m. Usually QSFP-100G-CWDM4-S module is more expensive than QSFP-100G-PSM4-S module. 

Q: Will Walsun 100GBASE-ER4 QSFP28 optical transceiver module work on a CWDM or DWDM Mux/Demux?

A: No. CWDM or DWDM Mux/Demux only support CWDM or DWDM transceiver. So our 100G ER4 module cannot be used directly with the channel port of CWDM Mux/Demux, because of its much greater working bandwidth than that of the channel port. But it is possible to transmit 100G data through the special port (provided that there is one on your device).

Conclusion

Probably the most common question we get from our customers when looking at our vast array of 100G QSFP28 Optical Transceivers to help optimize their network, is:

“Why are there so many different types?”

One might ask the same question (I know I have!) of the vast array of screwdrivers in a pro mechanic’s toolbox. Just as different screwdriver types (slotted, Phillips, TORX, and so on) are engineered to transfer energy more effectively from a screwdriver to the screw based on a given application,100G QSFP28 Optical Transceiver types are created with unique features to address the needs of specific network applications.

Knowing the tools – and more importantly when and where to use them – will save you valuable time, effort, and money. Here are some of the fundamental tools of the trade every network engineer should be familiar with.

QSFP28 SR4 and LR4

For most network engineers, the 100G SR4 and LR4 transceivers are those tools they reach for most often. The short reach SR4 is the 100G workhorse within head-ends and datacenters, using cost-effective 850nm lasers over parallel multimode fiber (MMF) for distances up to 70m (OM3), 100m (OM4), or 150m (OM5).

The “long reach” LR4s are the other 100G workhorse for applications up to 10km, using lasers in the nm range over duplex single mode fiber. These two definitely make up the volume of 100G transceiver deployments, but there are other tools in the QSFP28 “kit”.

QSFP28 SWDM4

The 100G SWDM4 transceivers are based on short wavelength division multiplexing. Instead of the four parallel lanes of 850nm used for SR4, SWDM4 multiplexes four separate wavelengths (850, 880, 910, and 940nm) to be then transported up to 150m (OM5) over a duplex MMF pair.

The SWDM4 “tool” gives a network engineer the option of upgrading their 10GBASE-SR duplex links to 100G without the need to run new parallel fiber, saving cost and time by leveraging off the existing cable plant.

QSFP28 CWDM4

The 100G CWDM4 provides a lower-cost alternative to the LR4 for links up to 2km. That rather large gap in the portfolio between 150m (SR4) and 10km (LR4) is well served by the 2km CWDM4.

As the name indicates, the 100G CWDM4 uses lasers based on the CWDM grid (, , , and nm) as opposed to the LR4, which is based on the LAN-WDM spacing (, , , and nm). Relaxing the requirements on the CWDM4 specs allows for a lower cost 100G solution optimized for 2km spans over duplex SMF.

QSFP28 PSM4

The 100G PSM4 provides the 10km singlemode reach of an LR optic, but with an MPO connector to provide a four-lane Parallel Single Mode (PSM) interface, rather than the duplex LC connector on the QSFP28 LR4. A network engineer thus has the ability to break out from a single QSFP28 100G port to 4xSFP28 25G ports, up to 10km away. The PSM4 module helps maximize faceplate density on your core and access routers when aggregating 25G links from subtending equipment. Very useful as wireless and FTTx starts migrating from 10G to 25G ports.

QSFP28 ER4/ER4L

The initial 100G 40km transceiver solutions were based on CFP/CFP2 ER4, and the higher module power capacity of the CFP form factors allowed for the higher power laser and APD (receiver) required for 40G links.

The initial QSFP28-based 40km solution was the ER4L (ER4 “lite”), which relaxed the optical power budget specifications in order to meet the QSFP28 module power consumption limitation. The “lite” meant that to reach 40km, the host switch/router would need to apply FEC (forward error correction) to meet the link requirements.

Thanks to advancements in component integration and die shrinks, a true 100G ER4 is now also available in the QSFP28 form-factor. What does this mean, and why would we want this when we already have the ER4L?

Latency is the primary drawback of FEC, as that additional bit of error correction coding does take time. For latency sensitive applications, having a true ER4 can be an essential tool in your kit.

QSFP28 ZR4

The 100G ZR4 was provides that eagerly awaited upgrade path from 10GBASE-ZR to 100G. Getting four lanes of 25G to reach 80km was no trivial task, and it required the addition of a silicon optical amplifier (SOA) as well as dispersion compensation within the module to meet the 80km link budget.

The resulting power consumption of the 100G ZR4 is thus higher (~5-6W) than its shorter reach counterparts, but it is an invaluable tool in upgrading those long 10G spans to 100G without the need for additional hops or external amplifiers.

QSFP28 DR1/FR1/LR1

Single-lambda QSFP28s are a perfect complement to the 400G QSFP-DDs for breakout applications, going from 400G to 4x100G. The QSFP28 DR1 (500m), FR1 (2km) and LR1 (10km) use a single laser with PAM4 modulation at 50Gbps which allows them to link with their 400G counterparts on a lane-by-lane basis.

Summary  

Going back to the question, “Why are there so many different types?” each type of 100G transceiver is a tool that can help a network engineer optimize their optical network topology for cost, latency, and efficiency. Sure, you might be able to get away with a single screwdriver for a DIY project, but like the professionals, your prized optical network deserves the right tools for the job.

Contact us to discuss your requirements of network cabling services. Our experienced sales team can help you identify the options that best suit your needs.