Monthly Archives: June 2017

How to Choose the Right 100G QSFP28 Optical Transceiver?

As an advanced manufacturing technology, QSFP28 optical transceivers have been highly favored by a large number of Ethernet users. We use large scale deployment and application of 100G optical transceivers in data center, Local Area Network(LAN), Wide Area Network(WAN), Ethernet switches and so on. Based on the unique low cost optical design package, we fully enjoy the great value crated by the new generation of 100G QSFP28 technology. There are many products with QSFP28 form factor like SR4, LR4, ER4, CWDM4, PSM4…

Facing so many different QSFP28 transceivers, we may be at a loss to choose an appropriate one for ourselves. At some extend, it really depends on our real demand. Due to limited space, we would mainly guide you how to choose a right one for your application from the perspective of transmission distance. Hope this article would help.

Transmission Distance

Different applications have given requirements for transmission distance, and the specific conditions and feasible measures will be fully covered in the following text.

Transmission Distance Is 100 m or Under 100 m

QSFP28 SR4 is highly recommended. The QSFP28 SR4 supports links of 70 m (OM3) and 100m (OM4) over multimode fiber with MPO connectors. It offers 4 independent transmit and receive channels, each capable of 25Gbps operation for an aggregated data rate of 100 Gbps. The QSFP28 SR4 modules are ideal for rack to rack connections in the data center and short reach telecom applications.

Transmission Distance Is Over 100 m But Under 10 km

QSFP28 LR4 is preferred. The QSFP28 LR4 is a fully integrated 4 × 25Gbit/s optical transceiver module, which supports distance up to 10 km. For long span 100GbE deployment, such a connectivity between two buildings, QSFP28 LR4 with duplex LC single-mode fiber cable is the perfect option.


Transmission Distance Exceeds 10 km

QSFP28 ER4 is ideal for very long transmission distance. The QSFP28 ER4 optical transceiver provides superior performance for 100G Ethernet applications up to 30 km links. The 100G QSFP28 ER4 module 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.

Note: When an optic says “10 km”, this is only a guideline. Actual distances can be significantly better or worse. It depends on your actual usages at large extend, including regular cleaning and maintenance.

How to Choose Based on the Same Transmission Distance?

We discussed the optimal options according different transmission distances, but it seems that it is hard to make a decision when the transmission distance is identical. QSFP28 CWDM4 and QSFP28 PSM4 are designed to meet the requirement for intermediate or mid-reaches for datacenter applications (500 m to 2 km). They both use WDM and parallel single mode fiber technologies and support transmission distance up to 2 km.


The CWDM4 provides a 100G Ethernet high-speed link with a maximum transmission distance of 2 km, which interfaces with LC duplex connectors. The CWDM4 module uses Mux/Demux technologies with 4 lanes of 25Gbps optically multiplexed onto and demultiplexed from duplex single-mode fiber.



PSM4 does not need a MUX/DEMUX for each laser but it does need either a directly modulated DFB laser (DML) or an external modulator for each fiber. With an MTP interface, PSM4 modules can bus 100Gb/s point-to-point over 2 km or can be broken out into dual 50Gb/s or quad 25Gb/s links for linking to servers, storage and other subsystems.

How to Choose?

From the aspect of an inner transceiver module structure, PSM4 can be more cost effective because of its lower component costs. However, from an infrastructure viewpoint, PSM4 would be more expensive when the link distance is long, mainly because PSM4 uses 8 optical single-mode fibers while CWDMs uses only 2 optical single-mode fibers.

Where Can Buy QSFP28 Transceivers at Low Cost ?

You may dizzy about the mess online shopping websites about fiber optic, and it is hard to find one online store that provides fiber optic products with high quality but low cost. Under this condition, you can try FS.COM which is an online shopping store about fiber optic communication. Our products has been deployed in data center and cloud computing applications all over the world.

For the mentioned 100G QSFP28 SR4, we have a big slump on it recently. Buying it now only needs $269, which is tripled on other online shopping stores. Here, we made a comparison between FS.COM and on Cisco QSFP-100G-SR4-S price. You can see it clearly by clicking the following link. Besides, all of our optical transceivers all 100% tested and fully compatible to many major brands such as Cisco, Juniper, Arista…

100G QSFP28 SR4

Cisco QSFP-100G-SR4-S at FS.COM:

Cisco QSFP-100G-SR4-S at


According to the above provided information and suggestion, you can choose the right QSFP28 transceiver for your application. FS.COM provides 100G QSFP28 modules for short reach, long reach and intermediate applications. For more details, please visit www.FS.COM.


An overview on Cisco Catalyst 3750-X Series Switch

In the later year of 2011, Cisco launched 3750 Series switch, with a purpose to improve LAN operating efficiency and resiliency for stackable switches. Cisco Catalyst 3750-X Series is one series of Cisco 3750 Series, which featured as high availability, scalability, security, energy efficiency, and ease of operation. The detailed information about Cisco Catalyst 3750-X Series switch would be provided in this article. In addition, we will guide you to plug your optical modules into this switch, all the installation and removing procedures as well as cautions are fully covered in the following passage.

Overview on Cisco Catalyst 3750-X Series switch

Cisco Catalyst 3750-X Series switch are 12-port and 24-port Gigabit Ethernet Small Form-Factor Pluggable (SFP) switches. You can see it more clearly in the following figure. Different from the traditional switch design, they additionally added some other functions, such as four optional network modules, redundant power supplies, and so on. Cisco Catalyst 3750-X Series switch are enterprise-class stackable switches and can be used for aggregation solutions in small core, midmarket, or branch office environments. The features and benefits of them are just listed in the following:


Figure1: Cisco Catalyst 3750-X Series switch with 12-port and 24-port

  • Four optional uplink network modules with Gigabit Ethernet or 10 Gigabit Ethernet
  • Dual redundant, modular power supplies and fans.
  • MACsec hardware-based encryption
  • Flexible NetFlow and switch-to-switch hardware encryption with the uplink service module
  • Enhanced Cisco EnergyWise for operational cost optimization
  • Ipv4 and IPv6 routing, multicast routing, advanced quality of service (QoS), and security features in hardware
  • Enhanced limited lifetime warranty (LLW) withe nest business day (NBD) advance hardware replacement and 90-day access to Cisco Technical Assistance Center (TAC) support
  • USB Type-A and type-B ports for storage and console respectively and an out-of-band Ethernet management port
Installing an SFP Module in the Switch

As we mentioned before, the Cisco Catalyst 3750-X Series switch are 12-port or 24-port SFP switches. That is to say, on this kind of switch, only SFP modules supported. The SFP modules provide copper or fiber-optic connections to other devices. These transceiver modules are filed-replaceable, providing the uplink interfaces when installed in an SFP module slot. The SFP modules have LC connectors for fiber-optic connection or RJ-45 connectors for copper connections. Before installing SFP module in this switch, please remember use only Cisco SFP modules on the switch.

Installation procedures:

Step1: Attach an ESD wrist strap to yourself and a properly grounded point on the chassis or the rack.

Step2: Remove the SFP transceiver from its protective packaging.

Step3: Check the label on the SFP transceiver body to verify that you have the correct model for your network.

Step 4: Remove the optical bore dust plug and set it aside.

Step 5: If the SFP module has a bale-clasp latch, move it to the open, unlocked position.

Installing Cisco SFP module

Figure2: Installing Cisco SFP module to the switch

Step 6: Align the SFP transceiver in front of the transceiver’s socket opening and carefully slide the SFP transceiver into the socket until the transceiver makes contact with the socket electrical connector.

Step7: Press firmly on the front of the SFP transceiver with your thumb to fully seat the transceiver in the module’s transceiver socket (see the below figure) on the Cisco Catalyst 3750-X Series switch.

Caution: If the latch is not fully engaged, you might accidentally disconnect the SFP transceiver.

Step9: For optical SFP transceiver, reinstall the dust plug into the SFP transceivers optical bore until you are ready to attach the network interface cable. Do not remove the dust plug until you are ready to attach the network interface cable.

Removing SFP modules

Step1: Attach an ESD-preventive wrist strap to your wrist and to a bare metal surface.

Step2: Disconnect the cable from the SFP module. For reattachment, note which cable connector plug is send (TX) and which is receive (RX).

Step3: Insert a dust plug into the optical ports of the SFP module to keep the optical interfaces clean.

Step4:If the module has a bale-clasp latch, pull the bale out and down to eject the module. If you cannot use your finger to open the latch, use a small, flat-blade screwdriver or other long, narrow instrument to open it.

Step5: Grasp the SFP module, and carefully remove it from the slot.

Removing Cisco SFP module

Figure3: Removing Cisco SFP module from the switch

Step6: Place the SFP module in an antistatic bag or other protective environment.


The Cisco Catalyst 3750-X Series switch provides high scalability, ease of management, and investment protection for evolving business needs. The installation and removing of SFP optical modules to the Cisco Catalyst 3750-X Series switch are easy operations. If you are looking for Cisco SFP modules for connection with Cisco Catalyst 3750-X Series switch with reasonable price and high quality, FS.COM would be a nice choice. Here, we offer large and in-stock SFP modules, they are 100% tested and fully compatible with Cisco 3750-X series switches. If you are interested with our products, please feel free to contact us.

Decoding 25G Ethernet And Its Optics

Most us of us may quite familiar with 10G, 40G and 100G Ethernet network, but we know little about 25G Ethernet, or even never heard about it. In the race of 10G, 40G and 100G Ethernet, it seems that 25G Ethernet lagged far behind. However, it is a good choice for network connectivity indeed. So what is 25G Ethernet and its benefits? And what about its cables and optical modules? The detailed information about 25G Ethernet would be provided in this article.

Overview on 25G Ethernet

Researched and developed by IEEE group, 25G Gigabit Ethernet is a standard for Ethernet connectivity. Compared with 10G, 40G and 100G Ethernet, 25G and 50G Ethernet were the latest developed Ethernet specification. 25G Ethernet Consortium was formed in July 2014 to support the specification of single-lane 25G Ethernet. It is an open organization to all third parties who wish to participate as members to enable the transmission of Ethernet frames at 25 or 50 Gigabit per seconds (Gbps) and to promote the standardization and improvement of the interfaces for applicable products.

25G Ethernet Specification

Based on single lane 25 Gb/s technology, the Consortium standard provides specifications for implementation, enabling Ethernet users to deploy cost effective Ethernet technologies. It is a technology that aimed at using (a) one 25 Gb/s lane to connect a single MAC operating at 25 GB/s by means of a Clause 49 PCS. The following figure shows how 25 Gb/s ports can be enabled.

25G Single Lane

Figure1: 25Gb/s SerDes Single Lane

For the configurations shown in Figure 1, 25Gb/s interfaces represent themselves as networking ports. They can auto-negotiate link speed by proprietary bit locations in extended capabilities registers.

Features and advantages of 25G Ethernet
  • Technology
    25G Ethernet technology is designed for application and infrastructure efficiency that results in a better data center ROI.
  • Robustness and reliability
    The 25G Ethernet technology is robust and reliable, and the products of Ethernet 25G are deigned to the highest standards and built to last. Weakness in one area can cascade and cause challenges that impact the entire system design and limit product reliability. The consequences would be too ghastly to contemplate.
  • Performance
    Industry analysts are predicting that 25GbE Ethernet will have the fastest adoption ramp ever for a new Ethernet technology. To make this forecast a reality requires not only 25 GbE technology that is both manufacturable and offers better features and capabilities, but also provides a true performance advantage.
  • Ease of adoption
    The IEEE group and 25G Ethernet Consortium have worked hard to ensure that 25G Ethernet offers a seamless upgrade to 10G Ethernet environments, with backwards compatibility that use the same 10GbE LC fiber cabling that has already been deployed in the data center.
  • Price
    Although 25GbE Ethernet is slightly more expensive than the 10GbE pricing, it still delivers a reasonable price. In fact the 25GbE pricing is very competitive, with only a 30% to 40% premium over 10GbE, and this premium is expected to come down over time. Overall, 25G Ethernet still offers a cost-effective solution for network connectivity.
25G SFP28 Optics

In general, there are three kinds of SFP28 optics, 25G SFP28 AOC and DAC cables as well as 25G SFP28 transceivers.

25G SFP28 AOC and DAC cable

The 25G SFP28 active optical cable is designed to overcome the bandwidth limitation of traditional copper cable so as to meet the high bandwidth in data center. It is hot pluggable and preterminated twin axial cable/fiber cable. The transmission distance can be 70 m by active optical cable with OM3 fiber. It is applicable to 25G and 10G Ethernet, data center and in-rack connection. For SFP28 DAC cable, there are two types: 25G SFP28 to SFP28 DAC and 100G QSFP28 to four SFP28 breakout DAC. These copper cables provide a cost-effective solution for connection with Top of Rack switches.


Figure2: 25G SFP28 Active Optical Cable

25G SFP28 transceivers

Basically, there are two kinds of 25G SFP28 transceiver, 25G SFP28 SR and 25G SFP28 LR optical transceiver. The 25G SFP28 SR designed to transfer data over short distance while the 25G SFP28 LR transceiver set for long distance transmission. The maximum transmission length of 25G SFP28 SR is 100 m over 50μm multimode optical fiber. The transmission distance of 25G SFP28 LR optical transceiver can be up to 10 km over single-mode fiber. Both the transceivers can be applied to data center, 10G&25G Ethernet, high-speed storage area networks and in-rack connection.


Figure3: 25G SFP28 Transceiver


25G Ethernet is taking off fast. It has a handful of very powerful data center and cloud vendors and suppliers-Google, Microsoft, Broadcom, Arista, Mellanox and Cisco. The 25G technology already exists in 100G will drive better cost efficiencies than 40G as well, saving cloud providers and enterprise data centers capital and operating expense. FS.COM provides large and in-stock 25G SFP+ cables and 25G SFP SR transceiver with high quality but low cost. If you are interested with our products, please feel free to contact us.

Why Choose 10GBASE-T SFP+ Transceiver for 10G Network Connection?

Over the years, 40G and 100G networks are developing rapidly, but nearly all new network building or network upgrading are based on 10G network. As an indispensable part in 10G network building, 10G optical transceiver has been designed and standardized by IEEE group as early as 2006. Compared with the prevalent 10GBASE-SR, 10GBASE-LR optical modules on the 10G transceiver market, 10GBASE-T SFP+ copper transceiver receives little attention. Different types have their own pros and cons, so why should we choose 10GBASE-T SFP+ transceiver for 10G network connection instead of others? This article would provide a satisfying answer for you.

Basic Information About 10GBASE-T SFP+ Transceiver

10GBASE-T meets all the bit-error rate (EDR) requirements of all the Ethernet and storage over Ethernet specifications, which is specifically designed for high speed communication links that require 10G Ethernet over cat6a or cat7 cable. It uses the familiar RJ45 connector and provides backward compatibility with legacy networks. 10GBASE-T SFP+ transceiver allows 10G bandwidth over existing infrastructrue and supports links up to 100 m using cat6a/7 cabling. It is compatible with a range of OEM’s including Cisco, Arista, Brocade, Juniper, Dell, Extreme, IBM. The SFP+ 10GBASE-T transceiver is available to many application equipment, including hubs, switches, routers, and switched interfaces on work area equipment.


The Benefits of 10GBASE-T SFP+ Transceiver
  • Low cost solutions are market stimulus

—Cost effective at up to 100 m distance

—Addresses PHY costs concerns in Enterprise market

—Enhances reach and conforms to structured cabling environment

  • Low cabling costs

—Ease and reuse of standard/structured cabling

—Ease of 1GBASE-T to 10GBASE-T migration

—Overall migration towards 10G Ethernet

  • High flexibility

—Multi-speed flexibility: Platforms support dual speed (1000BASE-T/10GBASE-T) or triple speeds (100BASE-T/1000BASE-T/10GBASE-T)

—Architecture Flexibility: Supports Top of Rack, Middle of Row or End of Row architectures

Why Choose 10GBASE-T SFP+ for Connection?

On the current 10G optical transceiver market, Direct Attach (DA) copper, 10GBASE-SR, 10GBASE-LR are highly favored by many Ethernet users. The DA copper seems cost less than the other 10G transceivers, but it has two major limitations: DA’s range is limited to 7 m; And because of the SFP+ connector, it is not backward-compatible with existing 1HbE infrastructure using RJ-45 connectors and twisted-pair cabling. By using 10GBASE-T copper transceiver, these limitations can be addressed. 10GBASE-T delivers 10GbE over cat6a or cat7 cabling terminated with RJ-45 jacks. It is backward-compatible with 1GbE and even 100Mgb Ethernet. Cat6a and cat7 cables will support up to 100 m.

10GBASE-T SFP+ transceiver on the switch

Figure: 10GBASE-T SFP+ transceiver connects the switch

In an existing data center, using 10GBASE-T SFP+ transceiver is quite convenient and efficient. Cat6 or more better twisted pair cabling rating have already been deployed in most existing data centers.10GBASE-T can be added incrementally to these data centers, either in new servers or via NIC upgrades “without forklifts”. New 10GBASE-T ports will operate with all the existing Ethernet infrastructure in place. With the upgrading of switches to 10GbE BASE T at whatever pace, the only effect will be noticeably enhanced network bandwidth.


As we discussed in this passage, 10GBASE-T SFP+ copper transceiver provides a cost-effective solution for 10G Ethernet network. It is of high port density, relatively high power and great flexibility. Thus, using 10GBASE-T SFP+ transceiver for building a new network or network upgrading is really a good deal. FS.COM provides large and in-stock 10GBASE-T SFP+ transceivers with several brands, such as Cisco, Dell, Arista…If you are interested with our products, please feel free to contact us.