Category Archives: Fiber Optic Transceivers

Cisco WS-C2960X-24PS-L vs WS-C2960S-24PS-L


A network switch is ubiquitous in data center: it functions as a multi-port network hardware device that bridges and routes data across multiple devices and corporate network segments. Cisco is one of the most famous and reliable switch vendors throughout the world. Among its dazzling switch product line, WS-C2960X-24PS-L and WS-C2960S-24PS-L are two Gigabit Ethernet switches that optimal for enterprise-class access for campus and branch applications. Merely judging from their physical appearance, these switches are nearly the same: configured with 24 10/100/100 Ethernet interface and 4 SFP uplinks. So when it comes to WS-C2960X-24PS-L vs WS-C2960S-24PS-L, what the differences is?

WS-C2960X-24PS-L vs WS-C2960S-24PS-L

As a member of Cisco Catalyst 2960-X series, WS-C2960X-24PS-L includes a single fixed power supply and are available with either the Cisco IOS LAN Base or LAN Lite feature set. It is designed for operational simplicity to lower total cost of ownership, enabling scalable, secure and energy-efficient business operations with intelligent services and a range of advanced Cisco IOS Software features. WS-C2960X-24PS-L also support Power over Ethernet Plus (PoE+) with up to 740W of PoE budget.

WS-C2960X-24PS-L vs. WS-C2960S-24PS-L

As for WS-C2960S-24PS-L, however, belongs to Cisco Catalyst 2960-S series. It enables reliable and secure business operations with lower total cost of ownership through a range of innovative features including FlexStack stacking with 20 Gbps of stack throughput (optional), Power over Ethernet Plus (PoE+) up to 740W, and Cisco Catalyst Smart Operations. WS-C2960S-24PS-L is ideal for deploying cost-effective wired connectivity in traditional desktop workspace environment, and enforcing basic security policies to limit access to the network and mitigate threats.


The linecard configuration of WS-C2960X-24PS-L vs WS-C2960S-24PS-L is nearly the same: both have 24 10/100/1000 Ethernet ports and 4 SFP uplink interface. And they are all stackable switches. The difference is that the switching capacity of WS-C2960X-24PS-L is slightly larger than WS C2960S-24PS-L, as shown in the following chart.

Model 10/100/1000 Ethernet ports Uplink interfaces Cisco IOS software image Available PoE power Switching capacity Stackable
WS-C2960X-24PS-L 24 4 SFP LAN Base 370 W 216 Gbps Optional
WS-C2960S-24PS-L 24 4 SFP LAN Base 370 W 176 Gbps Optional
WS-C2960X-24PS-L vs WS-C2960S-24PS-L: Connectivity Solution

Both configured with 24 10/100/1000Base Ethernet interface and 4 SFP uplinks, WS-C2960X-24PS-L vs WS-C2960S-24PS-L supports SFP transceivers to be fitted in the ports. The following chart show all the compatible SFP modules provided by FS.

WS-C2960X-24PS-L Compatible SFP Module
Product ID Description
11795 Cisco GLC-BX-D Compatible 1000BASE-BX-D BiDi SFP 1490nm-TX/1310nm-RX 10km DOM Transceiver
11802 Cisco GLC-BX-U Compatible 1000BASE-BX-U BiDi SFP 1310nm-TX/1490nm-RX 10km DOM Transceiver
11775 Cisco GLC-LH-SMD Compatible 1000BASE-LX/LH SFP 1310nm 10km DOM Transceiver
20358 Cisco GLC-EX-SMD Compatible 1000BASE-EX SFP 1310nm 40km DOM Transceiver
11779 Cisco GLC-ZX-SMD Compatible 1000BASE-ZX SFP 1550nm 80km DOM Transceiver
11773 Cisco GLC-T Compatible 1000BASE-T SFP Copper RJ-45 100m Transceiver
11773 Cisco GLC-TE Compatible 1000BASE-T SFP Copper RJ-45 100m Transceiver
11779 Cisco GLC-ZX-SM Compatible 1000BASE-ZX SFP 1550nm 80km Transceiver
11774 Cisco GLC-SX-MM Compatible 1000BASE-SX SFP 850nm 550m Transceiver
47241 Cisco CWDM-SFP-1470 Compatible 1000BASE-CWDM SFP 1470nm 80km DOM Transceiver
12672 Cisco GLC-GE-100FX Compatible 100BASE-FX SFP 1310nm 2km Transceiver for Gigabit Ethernet SFP Ports
11774 Cisco GLC-SX-MMD Compatible 1000BASE-SX SFP 850nm 550m DOM Transceiver
11775 Cisco GLC-LH-SM Compatible 1000BASE-LX/LH SFP 1310nm 10km Transceiver
WS-C2960S-24PS-L Compatible SFP Module
Product ID Description
11773 Cisco GLC-T Compatible 1000BASE-T SFP Copper RJ-45 100m Transceiver
11773 Cisco GLC-TE Compatible 1000BASE-T SFP Copper RJ-45 100m Transceiver
11774 Cisco GLC-SX-MM Compatible 1000BASE-SX SFP 850nm 550m Transceiver
11775 Cisco GLC-LH-SM Compatible 1000BASE-LX/LH SFP 1310nm 10km Transceiver
11779 Cisco GLC-ZX-SM Compatible 1000BASE-ZX SFP 1550nm 80km Transceiver
11779 Cisco GLC-ZX-SMD Compatible 1000BASE-ZX SFP 1550nm 80km DOM Transceiver
11795 Cisco GLC-BX-D Compatible 1000BASE-BX-D BiDi SFP 1490nm-TX/1310nm-RX 10km DOM Transceiver
11802 Cisco GLC-BX-U Compatible 1000BASE-BX-U BiDi SFP 1310nm-TX/1490nm-RX 10km DOM Transceiver
47241 Cisco CWDM-SFP-1470 Compatible 1000BASE-CWDM SFP 1470nm 80km DOM Transceiver
11774 Cisco GLC-SX-MMD Compatible 1000BASE-SX SFP 850nm 550m DOM Transceiver
11775 Cisco GLC-LH-SMD Compatible 1000BASE-LX/LH SFP 1310nm 10km DOM Transceiver
20358 Cisco GLC-EX-SMD Compatible 1000BASE-EX SFP 1310nm 40km DOM Transceiver

The switching capacity of WS-C2960X-24PS-L is larger than that of WS-C2960S-24PS-L, but they are both decent network switches that easy to operate. WS-C2960X-24PS-L vs WS-C2960S-24PS-L, the final decision should base on your specific networking environment. All the compatible SFP optical modules presented in the above chart are available at FS. FS manufactures a variety of high-standard optical transceivers, each of them are strictly tested for fully compatibility with the original brand. For more details, please visit or contact sales via

Compatible Optical Solution for HPE Procurve 3500yl-48G POE Switch (J8693A)

The HPE Procurve 3500 and 3500 yl switch series is a group of advanced intelligent-edge switches available with 24-port or 48-port fixed ports. These switches are with a variety of Gigabit Ethernet and 10/100Mbps interfaces. Both 24-port and 48-port switches have POE+, POE and non-POE options. Moreover, Gigabit Ethernet switches are with optional 10GbE module slot. HPE Procurve 3500yl-48G POE switch is one popular model of the 3500 yl switch series. This post will focus on this switch model and introduce compatible transceivers and cables that can be used in it.

HPE Procurve 3500yl-48G POE Switch

HPE Procurve 3500yl-48G POE switch has 44 autosensing 10/100/1000BASE-T ports and 4 dual-personality ports. Each of these four ports can be either an RJ45 10/100/1000 port with POE or an open mini-GBIC slot. It can be used as an advanced access layer switch or small distribution layer switch. With 44 fixed RJ45 10/100/1000BASE-T POE ports, it can support a considerable number of end application. And with an open module slot that supports a maximum of four 10GbE ports, it is flexible and promising when there’s need to upgrade to higher data rate or longer transmission distance.

48-port 3500yl-48g POE switch-1

Figure 1: 48-port HPE procurve 3500yl-48G POE switch.

It should be noted that each of the four mini-GBIC slots is shared with the associated 10/100/1000Base-T RJ45 port. If a mini-GBIC is installed in a slot, the associated RJ45 port is disabled.

4 dual-personality ports of HPE 3500yl-48G-POE

Figure 2: 4 dual-personality ports of HPE procurve 3500yl-48G POE switch.

Supported Transceivers and Cables in HPE 3500yl-48G POE Switch

The HPE Procurve 3500yl-48G POE switch is a multi-rate device that can support various types of network cable; when using the 4 mini-GBIC ports, different optical transceivers and cables can be used in them. For the 44 autosensing RJ45 ports, they can be used for 10/100BASE-T connectivity in half or full duplex mode, or for 1000BASE-T connectivity in full duplex mode. Ethernet cable like Cat5 can achieve the 10/100/1000BASE-T link. In terms of the mini-GBIC port, since there are three optional choices (X2, CX4 and SFP+) for the open module slot, 10G transceivers including X2, CX4 and SFP+ are possibly to be used. The following table explains what network optics and cable can be used. By the way, J8177B Gigabit 1000BASE-T mini-GBIC is not supported on the 3500 switch series.

Table: HPE compatible optical transceivers and cables.

HPE Part Number Description
J9054C HPE J9054C Compatible 100BASE-FX SFP 1310nm 2km DOM Transceiver
J9099B HPE J9099B Compatible 100BASE-BX-D BiDi SFP 1550nm-TX/1310nm-RX 10km DOM Transceiver
J9100B HPE J9100B Compatible 100BASE-BX-U BiDi SFP 1310nm-TX/1550nm-RX 10km DOM Transceiver
J4860C HPE J4860C Compatible 1000BASE-LH SFP 1550nm 80km Transceiver
J4859C HPE J4859C Compatible 1000BASE-LX SFP 1310nm 10km Transceiver
J4858C HPE J4858C Compatible 1000BASE-SX SFP 850nm 550m Transceiver
J9142B HPE J9142B Compatible 1000BASE-BX-D BiDi SFP 1490nm-TX/1310nm-RX 10km DOM Transceiver
J9143B HPE J9143B Compatible 1000BASE-BX-U BiDi SFP 1310nm-TX/1490nm-RX 10km DOM Transceiver
J8438A HPE J8438A Compatible 10GBASE-ER X2 1550nm 40km DOM Transceiver
J8437A HPE J8437A Compatible 10GBASE-LR X2 1310nm 10km DOM Transceiver
J9144A HPE J9144A Compatible 10GBASE-LRM X2 1310nm 220m DOM Transceiver
J8436A HPE J8436A Compatible 10GBASE-SR X2 850nm 300m DOM Transceiver
J9153A HPE J9153A Compatible 10GBASE-ER SFP+ 1550nm 40km DOM Transceiver
J9151A HPE J9151A Compatible 10GBASE-LR SFP+ 1310nm 10km DOM Transceiver
J9152A HPE J9152A Compatible 10GBASE-LRM SFP+ 1310nm 220m DOM Transceiver
J9150A HPE J9150A Compatible 10GBASE-SR SFP+ 850nm 300m DOM Transceiver
J9281B 1m (3ft) HPE J9281B Compatible 10G SFP+ Passive Direct Attach Copper Twinax Cable
J9283B 3m (10ft) HPE J9283B Compatible 10G SFP+ Passive Direct Attach Copper Twinax Cable

The above mentioned compatible optical transceivers and network cables can work well in HPE Procurve 3500yl-48G POE switch as the original models do, but are much more affordable. These compatible modules are tested in the switch and are ensured to work on it. If you know other working devices in this switch model, welcome to share with me and my readers.

How to Build a 10G Home Network?

The network has become the lifeblood for home and small business. It changes the way we live, work and communicate. Nobody today would deny the importance of the network, while it keeps evolving to satisfy the requirement of people. 10G networks, in this case, are no longer restricted to use in small and middle-sized business. It’s not uncommon for home to start with a 10G network setup. So how to get 10G home network? You may find some clues in this article.

Begin with Needs Assessment

Pretty much everything nowadays rely on a fast and reliable network, which leads to tremendous traffic and applications running on the networks and it keeps growing at high pace. Deploying 10G network at home eliminates network congestion at busy times while improves your productivity.   Better planning before deployment to ensuring your network can handle your business needs. You should ask yourself a few questions, such as how many computers, printers and other peripherals will connect to your network? How much wireless coverage will you need at your location? What type of mobile devices will need access to your network?


What Makes a 10G Home Network?

10G Ethernet makes streaming and sharing files over local network much faster. And 10GBASE-T standard is going mainstream into the consumer segment thanks to its lower power consumption and compatibility with existing infrastructure.


To build a 10G network, several components are indispensable: 10G core switches, access switches with 10G uplinks, and 10G network interface cards for servers and storage devices. The past few years had witness the price dropping of 10G network switches. For example, the cost of Ubiquiti Unifi and Eageswitch switches are only $200. And FS 10G network switch like S3800-48T4S only cost $480 by offering 48 100/1000Base-T and 4 10GE SFP+. When it comes to access switches with 10G uplink, FS S3800 series switches offers 24 ports with 4 10G uplinks at very decent price. These switches are well suited for home network use.

fs 10G network switch

What About 10G Cabling – 10GBASE-T, DAC or SFP+?

Upgrading the existing 1G network to 10G can be simple. As 10G switches also support 10GBASE-T, you can use the same RJ45 network cable to connect the 10G switch with your servers, storage and some other switches. The only difference is to use Cat6a network cable instead of Cat5e and Cat6 cable, or choose SFP+ 10GBASE-T modules with 2.5W power consumption and a maximum distance of 30 m.


For 10G switches that support 10G SFP+, you should use these ports if you have devices that come with 10G SFP+ port, or you need a 10G connection to other switches over 100m away. SFP+ ports look just the same as SFP ports on your Gigabit switches, but they’re now running at 10 Gigabit. For servers or storage devices with 10G SFP+ port, the most cost efficient way to connect is to use 10G DAC (direct attach twinax cable). These are basically copper cables with SFP+ connector on both sides, and they come in various lengths.


To connect switches over 100 m apart, a pair of SFP+ modules and the matching fiber cable are needed between them. Depending on the length required in home network, you can use 10G optics such as 10GBASE SR SFP module and multimode fiber to reach 300 meters. FS offers a wide range of 10G SFP+ modules and fiber patch cables for short and long distance transmission.


This article presents you some basic facts about 10 Gigabit Ethernet and how you can build a home network over 10 Gigabit. FS provides comprehensive 10G solutions: all the components mentioned to build a 10G home network are available at FS.COM, including Cat6a Ethernet cables, fiber patch cables, DACs and 10G SFP+ modules. For more details, please visit

40G Deployment: The Cost Difference Between SMF and MMF

40G network are now being extensively adopted within LANs and data centers. 100G is still predominantly in the carrier network, but could soon extend its stretch to your local network. There exists much confusion as to whether to choose single-mode fiber (SMF) or multimode fiber (MMF) for deploying 40G bandwidth, and how to get fully prepared for scaling to higher-speed 100G. If you are hesitating to make the choice, you may find this article helpful.

MMF optics and SMF optics cost

Multimode Fiber (MMF): Cost-effective With Higher Tolerance to Dirt

Cost-effectiveness: Multimode fiber (MMF) has been evolving to handle the escalating speed: OM3 has been superseded by OM4 and OM5 is there ready to use. MMF has a wider array of short distance transceivers that are easier to get. One of the liable argument that in favor of using MMF is that multimode optics use less power than single-mode ones, but only in condition that you have tens of thousands of racks. In essence, MMF still has its position under certain circumstances, like cabling within the same rack, in Fiber Channel and for backbone cabling in some new construction buildings.

cost-effective multimode fiber solution

Tolerance to Dirt: Multimode fiber tends to have a lot more tolerance to dirty connections than single-mode fiber. It can handle very dirty couples or connectors to ensure reliable and consistent link performance. Besides, it is easy to terminate, and more accommodating bend radius. So MMF is preferred by links that change frequently or are less than permanent.

multimode fiber MMF advantage in data center

Single-mode Fiber (SMF): Higher Capability and Better Future-proofing

Speed capability: Capacities are really vital for network growth. SMF does so with relatively larger capability than that of MMF. The gap between SMF and MMF cabling is much wider for high-density, high-speed networks. If you want to go further with SMF, say scaling to 100G or beyond, you simply need to upgrade the optics. Unlike using MMF, in which you have to upgrade the glass (OM3 to OM4 to OM5), the labor cost concerning this cannot be underestimated. The capacity for scaling of SMF alone makes it worth the cost. You can use single-mode for almost everything, no need for media conversion. SMF offers enough bandwidth to last a long time, making it possible to upgrade 100 Gbps to Tbps with CWDM/DWDM.

single-mode fiber SMF advantage

Future proofing: Despite the fact that SM optical transceivers usually cost higher than MM optics, SMF cabling is cheaper and can support much longer distance and reliable performance. Not to mention that bandwidth on SMF keeps going up and up on the same old glass. The good news is that the cost of SMF is dropping in recent years, and it is redesigning to run with less power, thus advocators of SMF think that it is pretty much the only rational choice for infrastructure cabling and the sure winner for today and tomorrow.

SMF and MMF: A Simple Comparison of Cost

There is no doubt that SMF is a better investment in the long run, but MMF still has a long way to go in data center interconnections. In fact the price difference of SMF optics and MMF optics can be minimized if you choose the right solution. Assuming to connect two 40G devices at 70 m away, let’s see the cost of SMF and MMF in the following chart.

Module Connector Type SMF or MMF Price 2 Connections 4 Connections 6 Connections
40GBASE-SR4 MPO12 MMF, OM4 $49.00 $564.48 $1128.96 $1693.44
40GBASE-BiDi LC MMF, OM4 $300.00 $1534.24 $2734.24 $3934.24
40GBASE-LR4 LC SMF, OS2 $340.00 $1,609.84 $2,969.84 $4,329.84
80 Gbit 160 Gbit 240 Gbit



Choosing the right fiber for your network application is a critical decision. Understanding your system requirements in order to select the appropriate fiber will maximize the value and performance of your cabling system. Be sure to select the right cable on the basis of aspects including link length, performance, and of course costs. FS provides a broad range of 40G optical transceivers and fiber patch cables with superior quality and fair price. For more details, please visit

How to Select Transceivers for White Box Switches?

White box switches, also known as open switches, have gained popularity in data centers. Because they provide high performance switching and enable users a broader choice in software and hardware purchase at the same time. However, it’s the openness of open switches that leads to other problems: is there any limitation on the use of optic modules for white box switches? How to choose an optical transceiver for open switches?

white box switches

Considerations When Selecting Transceiver for White Box Switches

As we know, open switches vendors usually sell switches either as bare-metal devices or preloaded with any compatible operating system, as requested by the purchaser. And there are many hardware and software vendors on the market. In order to achieve the desired performance with white box switches, some users may purchase hardware and software from different vendors. For example, one network operator may buy a white box switch from Dell, FS or HPE, but he will get a network operating system from Cumulus Linux. There is no fault of this action, but it will bring another problem—which type of optical transceivers can be used for the switch?

optical transceiver

According to the situation of white box switches on the market, there are two considerations should be taken into account when choosing an optical transceiver for white box switches.

The first one is the operating system (OS) of the switch. It’s known to us that there are various OS vendors like Cumulus Linux, Pica8 and HPE. They develop their own OS for their white box switches to get more market shares. Some of these companies also have their own optical transceiver production line. And some of them do not preclude the use of any industry-standard transceiver, which provide a freely choice for users to source standard components directly from manufacturers or from a broad range of re-sellers. Therefore, the transceivers from the corresponding OS vendor can be used for their open switches.

Another one is the optical transceiver itself. Not all white box switch vendors can provide transceivers for their switches. And some brand OEMs add enhancements to their standardized optic modules, which increases more cost on optics. However, some open switch vendors look forward to seeing an open standard without vendor lock-in. Therefore, cost-effective compatible optical transceivers that follow MSA SFF specification is another choice for white box switches. Among these compatible optical modules, most generic optical transceivers on the market can be used for white box switches.

Optical Transceiver Solution for White Box Switches

White box switches have been the way for web-scale data center operators who are able to drive down the cost and drive up efficiency and flexibility of their IT infrastructure, especially in some big companies like Facebook, Google or Amazon. And there is a growing group of companies that also want the same level of efficiency web-scale operators have achieved. How to realize this? More white box switches are required without question.

Under this situation, providers like FS.COM supplies several types of 10G, 25G, 40G and 100G network switches preloaded with FS OS or Cumulus OS for small and medium size networks or data centers. And all the generic optical transceivers in FS.COM are available for white box network switches.

Are White Box Switches Equal to OEM Switches?

With a low cost and excellent performance, white box switch has been a hot topic in the past few years. However, the basic definition of white box switch is still vague and ambiguous as a result of various reasons. Firstly, no one has ever made an accurate and standard conception of white box switches before; secondly, manufacturer with different interests and demands will deliberately obscure the definition of white box switch; thirdly, people who are unaware of the truth of Internet tend to be wrongly informed, which also lead to chaos in its definition. Some even simply equate a white box switch with an OEM switch. So what is a white box switch exactly?

white box switch

How to Understand White Box Switches?

According to its literal meaning, white box switches refer to switches without a label. However, there exists a deep connotation in white box switches which means this kind of switches doesn’t focus on brand. Based on this core idea, to better understand white box switches, here we might as well divide them into the following three models:

  • Bare-mental switch. It is the fundamental type of white box switch with no network operating system loaded on them except a boot loader. Customers can purchase a software through a third party like Big Switch, Cumulus, and Pica8 or even write a software by themselves. They ask for hardware support from hardware vendors and software support from software vendors.
  • White box switch. In this model, the supplier will offer switches with both hardware and software (the supplier only provide one of them, either hardware or software, but they got the authority of another from their partners). So customers can seek support for both hardware and software from one supplier. Besides, there are options for customers to choose for both hardware and software.
  • OEM switches. The hardware and software of the switch are manufactured and provided by an OEM (original equipment manufacturer). These OEMs design and manufacture a switch as specified by another company to be rebranded or not branded. This kind of switch is also called white box switch by many people. And suppliers offering this service are called white box supplier, especially when the supplier is small and not well-known.
The Market for White Box Switches

With a wide choice of networking software based on low-cost, commodity hardware, white box switches are bound to have a vast market in the future. Also, with the deployment of SDN, there is an increasing interest in white box switches within the IT community. In the previous text, we have divided white box switches into three types. Next, I will analyze the market for white box switches based upon this classification.

The market for white box switches

  • Bare-mental switches have been most widely used with a customer group mainly from networking giants like Google, Facebook, and Microsoft. They purchase a bare-mental switch and develop networking software by themselves. In china, large companies like Baidu, Alibaba, Tecent, and JD also tried this model, with Baidu being the most successful example. The reason why these giants chose such a kind of white box switch is that they are confident and capable enough to handle the development and operation of the software for a switch. Besides, these major technology firm have an extremely large-scale network, which requires them to control the network completely by themselves.
  • The customers for the second type are mainly distributed abroad with only a few in China. They mainly come from large financial companies, international data corporation and some network operators, whose size may only behind those internet giants. Cost saving is the most important driving force for them to buy a white box switch. Also, part of these enterprises chose it just for the differentiated operating system provided by white box suppliers who are willing to satisfy their specific demands through customized service.
  • The customer for the third type is distributed both at home and abroad. Although the market for this part is smaller than the first two, it has the largest potential for its customer group involving a large number of VARs (value added resellers), system integrators, IT products providers and many medium-sized clients. They adopt a white box switch for varied reasons such as improving the production line and saving costs.

Through this essay, we can see clearly that white box switch is much more than an OEM switch and the latter can be classified as one kind of the former. With a lower cost, excellent performance and huge market potential, white box switch will definitely grow up as the mainstream for switch adoption.

100G QSFP28 PAM4 or Coherent CFP?

The ever-increasing need for higher data rate in mobile data traffic, data centers and cloud services has pushed the access streams from 2.5Gb/s to 100Gb/s, and is demanding for 100Gb/s beyond without a stop. In today’s core network that has deployed 100G rates, there are QSFP28 optical transceivers including SR4, PSM4, CWDM4, LR4, ER4, etc., serving for a maximum 25km transmission distance. And there are 100G AOC, DAC and breakout cables generally for applications of tens of meters. 100G CFP/CFP2 modules including SR10, LR4 and ER4 support transmission distances of 150m to 40km. Until recent years, the telecom service providers are adopting new 100G DWDM technologies in their high capacity and long distance backbone applications. Coherent 100G DWDM transceivers are the first to be deployed for 100G long-haul applications, and then new technologies like PAM4 (Pulse Amplitude Modulation) are developed to meet lengths requirements for 100G metro network. This post is to discuss the issues on coherent and PAM4 100G DWDM transceivers.

Overview on 100G DWDM Transceivers

In the past few years, the adoption of 100G DWDM technologies is mainly focused on coherent DWDM optical transceivers, including CFP and CFP2. Until the year 2016, Inphi (a specialist in this area) offers pluggable 100G PAM4 QSFP28 DWDM transceivers to support 80km data center interconnect (DCI). The alternative for 100G DWDM coherent transceiver is given much attention. Besides, this new option for 100G DWDM transceiver also arouses hot discussion on which to choose. Knowing the characteristics and suited applications of them could help in selection.

QSFP28 PAM4 and Coherent CFP/CFP2

There are significant differences between QSFP28 PAM4 transceivers and coherent CFP/CFP2 transceivers, but they also have some relations in 100G applications. Contents below will go to details of these optical modules.


Before the announcement of PAM4, binary NRZ (non-return to zero) modulation format is used for 40G and 100G long-haul transmission systems. PAM4 has four distinct levels to encode two bits of data, essentially doubling the bandwidth of a connection. Currently the single-wavelength PAM4 modulation scheme is considered the most cost-effective, efficient enabler of 100G and beyond in the data center. The 100G DWDM transceiver utilizing PAM4 signaling is in QSFP28 form factor. The advantage is that the customers who want to build an embedded DWDM network can use this transceiver directly in the switch. On this side, it is simple and cost-effective solution. But there are some prerequisites: it needs amplification to get out of the blocks and dispersion compensation to go beyond 5-6km. Therefore, a separate DWDM multiplexer with an amplification system and dispersion compensation is required to connect data canters together.

single wavelength PAM4 100G

In another case, if the QSFP28 PAM4 module is added to an existing DWDM network, it must be a network already having right dispersion compensation modules (DCMs) and amplification system in place; if it is not, changes are required when QSFP28 PAM4 is later added.

Coherent CFP

CFP digital coherent optics (DCO) have a high speed digital signal processing (DSP) chip built in. They do not require separate DCMs. This is what makes CFP different from QSFP28. Instead, they have electronic dispersion compensation built in. Although the built-in DSP requires more power and adds cost in components, it releases the switch vendors from adding DSPs to their equipment. Coherent CFPs enables transmission distance of more than 1000km between sites.

CFP2 analog coherent optic (ACO) is half the width of the CFP. Existing CFP2 coherent DWDM optical transceivers are analog and require a separate DSP on the host board to take the full advantages of the coherent features. So it is suited for switch vendors who have fitted such a DSP, but it adds additional cost and power consumption on the main board.

CFP2 digital coherent optic (DCO), expected to be released in the coming two years, is more optimized than CFP2 ACO in that it has built-in DSP. This component will open up to all switch vendors using CFP2 without DSP. With different coherent CFPs optional, customers can pay only for what they need when they need it.

QSFP28 PAM4 or Coherent CFP?

This really should depend on the applications. According to ACG research (an analyst and consulting firm that focuses on the service providers’ networking and the telecom industry), the 100G PAM4 solution and coherent DWDM solution, together with IEEE802.3ba, cover different portions of the optical fiber reach in the data center interconnect. So when deploying a long distance 100G DWDM network with DWDM transceivers, the required transmission distance and available equipment should be taken into consideration when choosing a suitable pluggable module.

IEEE, PAM4, OIF coherent optical reaches


Using pluggable transceivers for embedded DWDM, where the DWDM functionality is in the transceiver and not a separate DWDM converter platform, offers the ultimate solution in terms of cost and simplicity. Both QSFP28 PAM4 and coherent CFP/CFP2 are all suited to this approach. They can be used for embedded DWDM networking or as part of an existing DWDM installation. They all enable the advantages of pluggable modules: simple installation, easy spares handling, lower cost of ownership and quick return on invest.

Can I Use the QSFP+ Optics on QSFP28 Port?

100G Ethernet will have a larger share of network equipment market in 2017, according to Infonetics Research. But we can’t neglect the fact that 100G technology and relevant optics are still under development. Users who plan to layout 100G network for long-hual infrastructures usually met some problems. For example, currently, the qsfp28 optics on the market can only support up to 10 km (QSFP28 100GBASE-LR4) with WDM technology, which means you have to buy the extra expensive WDM devices. For applications beyond 10km, QSFP28 optical transceivers cannot reach it. Therefore, users have to use 40G QSFP+ optics on 100G switches. But here comes a problem, can I use the QSFP+ optics on the QSFP28 port of the 100G switch? If this is okay, can I use the QSFP28 modules on the QSFP+ port? This article discusses the feasibility of this solution and provides a foundational guidance of how to configure the 100G switches.

For Most Switches, QSFP+ Can Be Used on QSFP28 Port

As we all know that QSFP28 transceivers have the same form factor as the QSFP optical transceiver. The former has just 4 electrical lanes that can be used as a 4x10GbE, 4x25GbE, while the latter supports 40G ( 4x10G). So from all of this information, a QSFP28 module breaks out into either 4x25G or 4x10G lanes, which depends on the transceiver used. This is the same case with the SFP28 transceivers that accept SFP+ transceivers and run at the lower 10G speed.

QSFP can work on the QSFP28 ports

A 100G QSFP28 port can generally take either a QSFP+ or QSFP28 optics. If the QSFP28 optics support 25G lanes, then it can operate 4x25G breakout, 2x50G breakout or 1x100G (no breakout). The QSFP+ optic supports 10G lanes, so it can run 4x10GE or 1x40GE. If you use the QSFP transceivers in QSFP28 port, keep in mind that you have both single-mode and multimode (SR/LR) optical transceivers and twinax/AOC options that are available.

In all Cases, QSFP28 Optics Cannot Be Used on QSFP+ Port

SFP+ can’t auto-negotiate to support SFP module, similarly QSFP28 modules can not be used on the QSFP port, either. There is the rule about mixing optical transceivers with different speed—it basically comes down to the optic and the port, vice versa. Both ends of the two modules have to match and form factor needs to match as well. Additionally, port speed needs to be equal or greater than the optic used.

How to Configure 100G Switch?

For those who are not familiar with how to do the port configuration, you can have a look at the following part.

  • How do you change 100G QSFP ports to support QSFP+ 40GbE transceivers?

Configure the desired speed as 40G:
(config)# interface Ethernet1/1
(config-if-Et1/1)# speed forced 40gfull

  • How do you change 100G QSFP ports to support 4x10GbE mode using a QSFP+ transceiver?

Configure the desired speed as 10G:
(config)# interface Ethernet1/1 – 4
(config-if-Et1/1-4)# speed forced 10000full

  • How do you change 100G QSFP ports from 100GbE mode to 4x25G mode?

Configure the desired speed as 25G:
(config)# interface Ethernet1/1 – 4
(config-if-Et1/1-4)# speed forced 25gfull

  • How do you change 100G QSFP ports back to the default mode?

Configure the port to default mode:
(config)# interface Ethernet1/1-4
(config-if-Et1/1)# no speed

Note that if you have no experience in port configuration, it is advisable for you to consult your switch vendor in advance.


To sum up, QSFP+ modules can be used on the QSFP28 ports, but QSFP28 transceivers cannot transmit 100Gbps on the QSFP+ port. When using the QSFP optics on the QSFP28 port, don’t forget to configure your switch (follow the above instructions). To make sure the smooth network transmission, you need to ensure the connectors on both ends are the same and no manufacturer compatibility issue exists.

The Basics of 1000BASE-SX and 1000BASE-LX SFP

Gigabit Ethernet has been regarded as a huge breakthrough of telecom industry by offering speeds of up to 100Mbps. Gigabit Ethernet is a standard for transmitting Ethernet frames at a rate of a gigabit per second. There are five physical layer standards for Gigabit Ethernet using optical fiber (1000BASE-X), twisted pair cable (1000BASE-T), or shielded balanced copper cable (1000BASE-CX). 1000BASE-LX and 1000BASE-SX SFP are two common types of optical transceiver modules in the market. Today’s topic will be a brief introduction to 1000BASE-LX and 1000BASE-SX SFP transceivers.

1000BASE in these terms refers to a Gigabit Ethernet connection that uses the unfiltered cable for transmission. “X” means 4B/5B block coding for Fast Ethernet or 8B/10B block coding for Gigabit Ethernet. “L” means long-range single- or multi-mode optical cable (100 m to 10 km). “S” means short-range multi-mode optical cable (less than 100 m).

1000BASE-SX is a fiber optic Gigabit Ethernet standard for operation over multi-mode fiber using a 770 to 860 nanometer, near infrared (NIR) light wavelength. The standard specifies a distance capability between 220 meters and 550 meters. In practice, with good quality fiber, optics, and terminations, 1000BASE-SX will usually work over significantly longer distances. This standard is highly popular for intra-building links in large office buildings, co-location facilities and carrier neutral internet exchanges. 1000BASE-SX SFP works at 850nm wavelength and used only for the purposed of the multimode optical fiber with an LC connector. 1000BASE-SX SFP traditional 50 microns of multimode optical fiber link is 550 meters high and 62.5 micron fiber distributed data interface (FDDI) multimode optical fiber is up to 220 meters. Take EX-SFP-1GE-SX as an example, its maximum distance is 550m with DOM support. The 1000Base-SX standard supports the multimode fiber distances shown in table 1.

1000Base-SX standard

Specified in IEEE 802.3 Clause 38, 1000BASE-LX is a type of standard for implementing Gigabit Ethernet networks. The “LX” in 1000BASE-LX stands for long wavelength, indicating that this version of Gigabit Ethernet is intended for use with long-wavelength transmissions (1270–1355 nm) over long cable runs of fiber optic cabling. 1000BASE-LX can run over both single mode fiber and multimode fiber with a distance of up to 5 km and 550 m, respectively. For link distances greater than 300 m, the use of a special launch conditioning patch cord may be required. 1000BASE-LX is intended mainly for connecting high-speed hubs, Ethernet switches, and routers together in different wiring closets or buildings using long cabling runs, and developed to support longer-length multimode building fiber backbones and single-mode campus backbones. E1MG-LX-OM is Brocade 1000BASE-LX SFP that operates over a wavelength of 1310nm for 10 km.


Difference Between LX, LH and LX/LH
Many vendors use both LH and LX/LH for certain SFP modules, this SFP type is similar with the other SFPs in basic working principle and size. However, LH and LX/LH aren’t a Gigabit Ethernet standard and are compatible with 1000BASE-LX standard. 1000BASE-LH SFP operates a distance up to 70km over single-mode fiber. For example, Cisco MGBLH1 1000BASE-LH SFP covers a link length of 40km that make itself perfect for long-reach application. 1000BASE-LX/LH SFP can operate on standard single-mode fiber-optic link spans of up to 10 km and up to 550 m on any multimode fibers. In addition, when used over legacy multimode fiber type, the transmitter should be coupled through a mode conditioning patch cable.

1000BASE SFP transceiver is the most commonly used component for Gigabit Ethernet application. With so many types available in the market, careful notice should be given to the range of differences, both in distance and price of multimode and single-mode fiber optics. Fiberstore offers a large amount of in-stock 1000BASE SFP transceivers which are compatible for Cisco, Juniper, Dell, Finisar, Brocade, or Netgear in various options. If you have any requirement of our products, please send your request to us.

Related Article: Compatible SFP for Cisco 2960 Series Switches

Still Have Problems with Quanta LB4M and LB6M 10G Switches?

With the growth of virtualization, cloud-based services and applications like VoIP, video streaming and IP surveillance, various 10G switches with diverse functions spring out on the market. Quanta LB4M and LB6M 10G switches are two types popular 10G switches among them. However, there is few user manuals on the Internet, which brings inconveniences for users. This post intends to give a simple introduction to Quanta LB4M and LB6M 10G switches and some solutions for the common problems that may arise in their operating process.

Basis of Quanta LB4M and LB6M 10G Switches

The Quanta LB4M is a modular Gigabit Ethernet backbone switch designed for adaptability and scalability. This switch supports up to 48 Gigabit Ethernet ports to function as a central distribution hub for other switches, switch groups, or routers. And it offers 2 SFP+ interfaces for 10G port on the daughter board. While the Quanta LB6M switch provides 24 10GbE SFP+ ports and 4 1000BASE-T ports, which makes it more popular than LB4M. For these two switches, many users think highly of its performance. But there are also some passive remarks due to the limited documentation.

quanta lb4m & lb6m

Problem & Solution

If you have searched on the Internet, you will find that there are so many questions about Quanta LB4M and LB6M switches in all aspects like lack of instructive manuals, the operating issues, IP setup problems, etc. Here is a collection of several popular ones in discussion forums and blogs. Hope it will help you.

Quanta LB4M MAC Entry Problem

Use the LB4M in an active/passive configuration for SAN (Storage Area Networking). The two SAN nodes of the user have HA (fail over) and for that it uses a virtual IP which is moved between the two head nodes in case of failure. But the virtual IP MAC is missing from the LB4M switches “mac-addr-table”, which in turn leads to this virtual IP to be mirrored to all ports on that vlan.

Solution: right MAC (Media Access Control) mapping is the core of Ethernet switches. The first choice is to determine whether the MAC address of the switches is valid. Then pick a random address with the same 3-byte prefix as one of your physical MAC addresses and see if the switch accepts it. Another choice is to check the port security where the switch only accepts traffic from a single MAC address, either hard-coded in the config or the first one “seen” on that port.

LB4M Ports Are Deactivated and Backup Image Is Corrupt

Bought a Quanta LB4M and configured a management IP for the Web interface. After rebooting the switch as told, the screen showed that the crc-checksum for both the first and the backup image are corrupt, and another image is needed via the modem.

Solution: try to get upload an image via the modem to fix the problem. And then test it to check if the switch works.

Connect Dell 2848 with SFP to Quanta LB6M?

Dell 2848 switch has four SFP ports, while the Quanta LB6M has 24 10GbE SFP+ ports and 4 1000BASE-T ports. And other devices also need to be connected with. Then how to connect Dell 2848 with Quanta LB6M? The data center is currently running on a 1Gb Cat 6 cables.

Solution: using 10Gb SFP+ LC modules for the Quanta LB6M, 1Gb SFP LC modules for the Dell 2848 and then run MM fiber. Since SFP+ and SFP ports are not compatible, OEM services are another choice to solve this type of problem. FS.COM offers various kinds of customized service to meet customers’ different demands.

How to Avoid the Problems Mentioned Above?

It is undeniable that the Quanta LB4M and LB6M 10G switches are popular among users, which can be seen from the remarks in some forums. But since there is few instructive documents to describe these two types of switches, it will be difficult to solve the problems met in the operating process immediately. FS.COM supplies various kinds of 10G switches to meet the demand of Gigabit access or aggregation for enterprise networks and operators customers. Other 10G optics like 10G transceiver and 10G DAC & AOC are also available. Welcome to visit our website for more information.