Category Archives: Optical Transceiver Solution

100G QSFP28 Fiber Optic Modules and Standards

The developing of 100G fiber optic transceiver has experienced a lot of challenges, thus various types of 100G fiber optic transceivers are being invented. Many 100G modules appeared on the market for a while and disappeared soon. Now it seems that 100G QSFP28 module will win the competition. It has the same cabling structure as 40G QSFP+ module and high density feature, which allows network upgrade to 100G with lower cost and less time. This post will introduce several commonly used 100G QSFP28 modules and standards.

100G QSFP28

QSFP28 module uses four lanes for 100G optical signal transmitting like 40G QSFP+. However, each lane of QSFP28 can transmit 25G optical signal. To fit the various requirements in practical applications, IEEE and MSA standards that support different transmission distances and fiber types are being published.

100G QSFP28 SR4 

100G QSFP28 SR4 is a standard published by IEEE. 100G QSFP28 SR4 module uses eight multimode fibers for 100G dual-way transmission over 850nm. It can support a transmission distance up to 70m over OM3 and 100m OM4 with a MTP interface. 12-fiber MTP OM3/OM4 trunk cables are suggested to be used with QSFP-100G-SR4 modules. 100Gbase-SR4 QSFP28 is the most popular QSFP28 module according to research.

100G QSFP28 LR4

100G QSFp28 LR4 is another 100G standards published by IEEE. It focuses on longer transmission distance over single-mode fiber. 100G QSFP28 LR4 has a duplex LC interface and uses WDM technologies to achieve 100G dual-way transmission over four different wavelengths around 1310nm. It can support distances up to 10km.

Although IEEE has defined two 100G standards separately for short and long distances, the requirements of various applications cannot be fully satisfied. For instances, the 100G-QSFP-LR4 module can support 10km, which is too much for a lot of single-mode applications. It would be uneconomical to buy a 10km module for just 1km or 2km application. MSA has published two 100G standards — 100Gbase-PSM4 and 100Gbase-CWDM4, which can help to decrease the cost of 100G deployment.

100G QSFP28 PSM4

100G QSFP28 PSM4  module has a MTP interface working on wavelength of 1310nm for 100G transmission over single-mode fibers. It can support transmission distance up to 500 meters. 100G QSFP28 PSM4 module is much cheaper than 100Gbase-LR4 QSFP28 module. And 500 meter’s transmission distance can cover a wide range of applications.

100G QSFP28 CWDM4

For longer transmission distance, 100G QSFP28 CWDM4 is suggested, which supports a distance up to 2km over single-mode fiber optic cable. 100Gbase-CWDM4 standard is published by MSA, which is a more cost-effective solution for a wide range of applications compared with 100Gbase-LR4. This module uses CWDM technologies to transmit the 100G optical signal via a duplex LC interface over wavelengths near 1310nm.

100G QSFP28 DAC

100G QSFP28 family also includes a series of direct attach cables. There are mainly two types of QSFP28 DAC, which are QSFP28 to QSFP28 DAC and QSFP28 to SFP28 DAC. These QSFP28 DACs are cost-effective solution for 100G transmission less than 5 meters.

100G QSFP28 Module Interface Fiber Type Distance Standards
100Gbase-SR4 QSFP28 MTP Multimode 70m (OM3); 100m (OM4) IEEE
100Gbase-LR4 QSFP28 LC Duplex Single-mode 10km IEEE
100Gbase-PSM4 QSFP28 MTP Single-mode 500km MSA
100Gbase-CWDM4 QSFP28 LC Duplex Single-mode 2km MSA
Conclusion

There are many ways to transmit to 100G network. 100G QSFP28 modules are the suggested methods. Both IEEE and MSA published standards for 100G QSFP28. For short distance transmission over multimode, 100Gbase-SR4 QSFP28 module is suggested. For single-mode applications, 100Gbase-PSM4 supporting 500m, 100Gbase-CWDM4 supporting 2km and 100Gbase-LR4 supporting 10km are available. The above table shows the basic information of these modules for your reference.

Difference Between 100G-QSFP-PSM4, 100G-QSFP-SR4 and 100G-QSFP-LR4

QSFP28 fiber optic transceiver is becoming the preferred solution for 100G network. It has the same outside looking as the 40G QSFP+ transceiver. But it has a 4*25G electrical interfaces which can transmit optical signals up to 100G. The part numbers of the QSFP28 transceivers are usually market as 100G-QSFP-xx. Now there is a wide selection of 100G QSFP28 modules for 100G Ethernet link, including fiber optic transceiver and direct attached cable. Different part numbers of 100G modules are making customers confused. This post will introduce the differences between the three 100G QSFP28 modules: 100G-QSFP-PSM4, 100G-QSFP-SR4 and 100G-QSFP-LR4.

100G QSFP

Transmission Mode

It is known that QSFP28 modules generally use four lanes to transmit 100G with each lane supporting 25G. Thus, the transmission method is just like 40G QSFP+ transceiver. 100G QSFP28 SR4, LR4 and PSM4 all use the 4*25 transmission mode. However, both the QSFP28 SR4 and QSFP28 PSM4 use a 12-fiber MTP interface which achieves dual-way 100G transmission over 8 fibers at the same time. QSFP28 LR4 uses a LC duplex fiber optic interface for 100G transmission on two directions at the same time. QSFP28 LR4 transmit optical signals over four different wavelengths around 1310nm with each wavelength carrying 25G optical signal. The wavelength ranges of the four lanes are as following:

  • 1294.53nm-1296.59nm
  • 1299.02nm-1301.09nm
  • 1303.54nm-1305.63nm
  • 1308.09nm-1310.19nm
Transmission Media and Distances

The three modules can support different transmission distances. 100G-SR4 QSFP28 module works over wavelength of 850nm and is used with 12-fiber MTP OM3 or OM4 multimode fiber cables for short transmission distances up to 100m. 100G-LR4 QSFP28 module is suggested to be used with single-mode fiber. It works over 1310nm wavelengths and can transmit 100G signals up to 2km. 100G-PSM4 QSFP28 is also used with 12-fiber MTP fiber cables but the fiber type is single-mode and the transmission distance is up to 500m.

100G-QSFP-SR4

Cabling Structure

The transmission mode of the fiber optic transceiver plays an important role during fiber cabling. 100G-QSFP-SR4 and 100G-QSFP-LR4 are invented for short distance transmission and long distance transmission separately. However, the have different cabling structure. The former requires a multi-fiber cabling structure based on 12-fiber MMF MTP interfaces. While 100G-QSFP-LR4 just required the traditional two-fiber SMF cabling structure. In this case, the conversion between multimode fiber to single-mode fiber would be complex as they used totally different cabling structure. Thus, 100G-QSFP-PSM4 is invented which runs over single-mode fiber, but uses the same cabling structure as 100G-QSFP-SR4. With 100G-QSFP-PSM4, the conversion between multimode and single-mode would save more without changing the existing fiber cabling structure.

100G QSFP28 Transceiver Data Rate Interface Fiber Type Transmission
Distance		 Wavelengths Cabling Structure
100G-QSFP-SR4 4*25G MTP MMF 70m (OM3);
100m (OM4)		 850nm 12-Fiber MTP
100G-QSFP-LR4 4*25G LC SMF 2km 1310nm LC Duplex
100G-QSFP-PSM4 4*25G MTP SMF 500m 1310nm 12-Fiber MTP
Conclusion

The above table listed the basic information of the three modules for your referent. 100G-QSFP-SR4 are suitable for short distance transmission over OM3 or OM4 fiber using 12-MTP fiber cabling system. 100G-QSFP-PSM4 also has a 12-fiber MTP interface but it can support a transmission distance up to 500m over SMF. 100G-QSFP-LR4 is suitable for long transmission distance up to 2km over two single-mode fibers.

Related Article: 40G vs 100G: Which One Is Worth the Investment?

Cisco S-Class vs Non-S-Class Module

Cisco switches and fiber optic transceivers are considered as the benchmarks of the market with a market share more than 50%. With the development of fiber optic network, Cisco has developed a variety of fiber optic transceivers for different applications and has built a system to name each transceiver. For instance, the most commonly used 10G Cisco modules like SFP-10G-SR and SFP-10G-LR have part numbers which can accurately descript their biggest features. SR means “short range” and LR means “long range”. However, customers find the part numbers of some Cisco modules are named with an “S”, like SFP-10G-SR-S and SFP-10G-LR-S. Cisco calls them S-class modules. People might get confused by these Cisco S-class modules. Cisco S-Class vs Non-S-Class module, or SFP 10G SR S vs SFP 10G SR, which one should you choose?

sfp 10g sr s vs sfp 10g sr

Cisco S-Class Module VS Cisco Non-S-Class Module

Cisco only published four 10G S-class SFP+ modules and two 40G S-class QSFP+ modules. The following table listed Cisco S-class modules. Cisco S-class modules seem to have no differences from the non-S-class modules. However, if you read the specification of these modules and the suggestions from Cisco, you will find the differences.

Data Rate S-Class Module Non-S-Class Module Media
10G SFP-10G-SR-S SFP-10G-SR MMF (duplex)
10G SFP-10G-LR-S SFP-10G-LR SMF (duplex)
10G SFP-10G-ER-S SFP-10G-ER SMF (duplex)
10G SFP-10G-ZR-S SFP-10G-ZR SMF (duplex)
40G QSFP-40G-SR4-S QSFP-40G-SR4 MMF (ribbon)
40G QSFP-40G-LR4-S QSFP-40G-LR4 SMF (duplex)

Protocol

The standard non-S-class Cisco modules like SFP-10G-SR and SFP-10G-LR can support three protocols including Ethernet, OTN (Optical Transport Network) and WAN-PHY (Wide Area Network Physics). However, the S-class modules can only support Ethernet protocol.

Temperature Range

Compared with Cisco C-class modules which can be operating with three different temperature ranges, the Cisco S-class modules can only support the commercial temperature ranges which is 0 to 70°C (32 to 158°F).

  • Commercial temperature range (COM): 0 to 70°C (32 to 158°F)
  • Extended temperature range (EXT): -5 to 85°C (23 to 185°F)
  • Industrial temperature range (IND): -40 to 85°C (-40 to 185°F)

Transmission Distance

Cisco has introduced that the S-class modules are suggested to be used in enterprise network. In addition, the operating temperature range is smaller, thus, S-class module is recommended for shorter transmission distance applications compared with other standard modules.

Price

As the performance of Cisco S-class modules are no better than other modules, why did Cisco published these modules? This is because Cisco S-class modules have lower prices, which is also their biggest sale point.

cisco s-class module

Should I Choose Cisco S-Class Module?

In conclusion, S-class can only support Ethernet protocol and has a commercial temperature range, which is suggested to be used in applications that no special long distance, temperature tolerances, or other special features are required. But many people might not select S-class modules, considering about the future use. As Cisco original branded transceivers are expensive, many people will use third party modules which are much cheaper but is compatible with Cisco devices. A Cisco compatible non-S-class module could be much cheaper than a Cisco original brand S-module. But it can provide almost the same performance as the Cisco original branded non-S-class module.

Related Article: Cisco SFP-10G-SR: All You Need to Know

A Comprehensively Understanding of Cisco 10GBASE SFP+ Modules

Differences Between QSFP-40G-SR4, QSFP-40G-CSR4 and QSFP-40G-CR4

When selecting 40G fiber optic transceivers, customers are easily confused by the standards and models of the 40G modules. This is because the standards of transceiver are generally the combinations of letters and numbers. Some of the standards and models are really similar to each other. Thus, this post is to offer an illustration of three 40G modules whose standards and models are easily misidentified. These 40G modules are QSFP-40G-SR4, QSFP-40G-CSR4 and QSFP-40G-CR4. Details of the three modules will be firstly introduced separately. Then comparison in specific applications among them will be offered.

QSFP-40G-SR4 (40Gbase-SR4)

The three standards look similar. However, they actually have great differences from each other. Here starts from 40Gbase-SR4. Many vendors use “QSFP-40G-SR4” to identify 40G QSFP+ modules that support by 40Gbase-SR4 standards. 40Gbase-SR4 QSFP+ is the most popular 40G fiber optic transceiver for transmission in short distances. 40GBASE-SR4 QSFP+ module supports link lengths of 100m and 150m, respectively, on OM3 and OM4 multimode fibers. It is a parallel fiber optic transceiver containing a MTP/MPO interfaces, which use 4*10G transmission pattern. With four 10G SFP+ lane in one module, QSFP-40G-SR4 can achieve 40G optical signal transmitting and receiving at the same time via a ribbon fiber cable. The following picture shows how signals are transmitted over a MTP ribbon fiber cable.

40G-SR4 transmission

QSFP-40G-CSR4 (40Gbase-CSR4)

The working principle of QSFP-40G-CSR4 module is similar to QSFP-40G-SR4 module. Both QSFP-40G-CSR4 module and QSFP-40G-SR4 module has MTP/MPO interface. However, 40Gbase-CSR4 module can be regarded as an upgraded version of the 40Gbase-SR4 module. It can support longer 40G transmission up to 300m on OM3 and 400m on OM4. Transmission distance is the biggest different form the two 40G fiber optic transceivers.

QSFP-40G-CR4 (40Gbase-CR4)

QSFP-40G-CR4 module is very much different from the above mentioned two 40G modules. It is a pre-terminated copper cable with both ends terminated with QSFP+ connector. It is known as 40G QSFP+ cable or 40G QSFP+ direct attach cable. Limited by the property of copper cable, QSFP-40G-CR4 can only reach a transmission distance of 7 meters.

QSFP+ DAC

Which One Should You Choose QSFP-40G-SR4, QSFP-40G-CSR4 or QSFP-40G-CR4?

As the above mentioned, QSFP-40G-SR4, QSFP-40G-CSR4 and QSFP-40G-CR4 are all designed for 40G transmission in short distances. Which one is better for your applications? This should be decided by the specific applications. Generally, there are two types of transmission in 40G network: 40G to 40G transmission and 40G to 10G transmission. All the three modules can accomplish the two applications. However, there are some differences.

40Gbase SR4

QSFP-40G-SR4 and QSFP-40G-CSR4 uses the same connection methods for 40G-40G and 40G-10G transmission. For 40G to 40G connections, a length of MTP trunk cable can be used to connect two QSFP-40G-SR4 or QSFP-40G-CSR4 modules to form the whole link. The following picture takes Cisco Nexus 9396PX 40G connection as an example. For 40G to 10G connection, a MTP-8LC harness cable can be used to connect a QSFP-40G-SR4 or QSFP-40G-CSR4 module with other 10G devices.

40G to 40G connection with QSFP-40G-CSR4

For 40G QSFP+ to QSFP+ direct attach cable (DAC), no additional fiber patch cables are need for 40G to 40G connection. Directly insert the two QSFP+ connector in to the devices, 40G transmission can be achieved. For 40G to 10G transmission, another version of QSFP+ DAC can be used, which is known as QSFP+ to 4 SFP+ direct attach cable. The following picture shows how to connect a 40G port to four 10G port by using a QSFP+ to 4 SFP+ copper cable.

40G to 10G connection

If your transmission distance is less than 150 meters but longer than 7 meters, then QSFP-40G-SR4 module would be the best choice. If your transmission distance is longer than 150 meters, QSFP-40G-CSR4 module is suggested for better network performance. If the transmission distance is less than 7 meters, then QSFP-40G-CR4 modules would be the most cost-effective solutions.

Related Articles: How to Connect 40G QSFP+ SR4 Transceivers to Network?

                              40G Transceiver Module: QSFP+ Module And CFP Module

Brocade 40G Switch ICX 7750-26Q Cabling Solution

The Brocade ICX 7750 is a series of switches which can provide high-availability capabilities and flexible stacking architecture for 10/40G applications. Brocade ICX 7750 series switches are usually used for 10/40G aggregation and core distribution. Brocade ICX 7750-26Q is a member of Brocade ICX 7750 series, which is a 1U high performance switch with up to 32 40G QSFP+ ports (six optional). This post will offer optics and cabling solution for Brocade ICX 7750-26Q switches.

Brocade ICX 7750-26Q transceivers

Basic of Brocade ICX 7750-26Q Switch

The above picture shows a Brocade ICX 7750-26Q switch from FS.COM testing center. On the front panel of Brocade ICX 7750-26Q switch, there are 26 40G QSFP+ ports, ICX 7750-6Q module with 6 40G QSFP+ ports can be added on the rear panel of this switch. Thus up to 32 40G QSFP+ ports can be supplied by Brocade ICX 7750-26Q switch. It can support transmission applications for both 40G to 40G and 40G to 10G.

Brocade ICX 7750-26Q 40G to 40G Applications

Brocade ICX 7750-26Q can support 40G transmission for both short distances and long distances by using different 40G QSFP+ transceivers and fiber optic cables. The following picture shows the cabling methods for 40G point to point connection. Choosing the proper fiber patch cable for two QSFP+ modules, 40G data transmission between two Brocade ICX 7750 switches can be achieved. In this case, two Brocade 40G-QSFP-LR4 compatible transceivers and a length of LC to LC duplex single-mode fiber patch cable are being used.

brocade-icx7750 40G connection

Brocade compatible QSFP+ to QSFP+ direct attach cables including (direct attach copper cables and active optical cables) are cost-effective alternatives for Brocade ICX 7750-26Q 40G connections in short distances.

Brocade 40G-QSFP-QSFP-AOC

Brocade ICX 7750-26Q 40G to 10G Applications

As mentioned Brocade ICX 7750-26Q switch can also support 40G to 10G applications. A 40G QSFP+ port can be splitted into four 10G SFP+ ports, which can achieve transmission between 10G and 40G. There is a wide selection of Brocade ICX 7750-26Q switch 40G to 10G connections. Fanout assemblies play an important role to support these connections.

brocade-icx7750 40G connection

The above picture shows the commonly used connection methods for Brocade ICX 7750-26Q 40G to 10G connections. In this case, Brocade QSFP-40G-PLRL4 compatible transceiver is being used one the Brocade ICX 7750-26Q side. A length of MTP to four duplex LC breakout cable is being used to connect Brocade QSFP-40G-PLRL4 with four 10G SFP+ transceivers inserted in several 10G switches on the opposite side. Also, QSFP+ to SFP+ DACs and AOCs can also be used.

Brocade 40G-QSFP-SR4

Brocade ICX 7750-26Q Fiber Optic Transceivers and Cabling Solutions

Brocade ICX 7750-26Q switch provides flexible and high density networking environments. This post only provides the optics and cabling solution for Brocade ICX 7750-26Q switch. The following table listed the Brocade ICX 7750-26Q compatible transceivers and cables for you references. Kindly visit FS.COM Transceiver modules for BROCADE ICX 7750 page for more details about Brocade ICX 7750 series switches, if you are interested.

Brocade Compatible Modules Description
40G-QSFP-LR4 40GBASE-LR4 QSFP+ optic (LC), for up to 10 km over SMF
QSFP-40G-PLRL4 40GBASE-PLRL4 QSFP+ (MTP/MPO), 1km over SMF,
40G-QSFP-SR4 40GBASE-SR4 QSFP+ optic (MTP), 100 m over MMF
40G-QSFP-SR4-INT 40GBASE-SR4 QSFP+ optic (MTP), 100 m over MMF, compatible with 10GB BASE-SR
40G-QSFP-QSFP-C-0101 40 GbE direct-attached QSFP+ to QSFP+ active copper cable, 1 m
40G-QSFP-QSFP-C-0301 40 GbE direct-attached QSFP+ to QSFP+ active copper cable, 3 m
40G-QSFP-QSFP-C-0501 40 GbE direct-attached QSFP+ to QSFP+ active copper cable, 5 m
40G-QSFP-QSFP-AOC-0101 40 GbE direct-attached QSFP+ to QSFP+ active optical cable, 1 m
40G-QSFP-QSFP-AOC-0301  40 GbE direct-attached QSFP+ to QSFP+ active optical cable, 3 m
40G-QSFP-QSFP-AOC-0501 40 GbE direct-attached QSFP+ to QSFP+ active optical cable, 5 m
40G-QSFP-4SFP-C-0101 4×10 GbE direct-attached QSFP+ to 4 SFP+ copper breakout cable, 1m
40G-QSFP-4SFP-C-0301 4×10 GbE direct-attached h QSFP+ to 4 SFP+ copper breakout cable, 3m
40G-QSFP-4SFP-C-0501 4×10 GbE direct-attached QSFP+ to 4 SFP+ copper breakout cable, 5m
40G-QSFP-4SFP-AOC-0101  4×10 GbE direct-attached QSFP+ to 4 SFP+ active optical cable, 1m
40G-QSFP-4SFP-AOC-0301 4×10 GbE direct-attached QSFP+ to 4 SFP+ active optical cable, 3m
40G-QSFP-4SFP-AOC-0501  4×10 GbE direct-attached QSFP+ to 4 SFP+ active optical cable, 5m