Cabling Solution for Upgrading to 40G and 100G


Migrating from 10G (that uses two fibers in either a SC Duplex or a LC Duplex connector) to 40G and 100G will require a lot more fibers and a different type of connector. The way that optical fiber cabling is deployed for 10G can facilitate an easier migration path to 40G and 100G in the future. An effective migration strategy needs to provide a smooth transition to the higher Ethernet speeds with minimum disruption and without wholesale replacement of existing cabling and connectivity components.

10G use LC duplex cabling

Optical fiber cabling is commonly deployed for backbone cabling in data centers for switch to switch connections and also for horizontal cabling for switch to server and storage area network connections. The use of pre-terminated optical fiber cabling can facilitate the migration path to 40G and 100G Ethernet in the future. Figure below illustrates a pre-terminated cable assembly (MPO cassette) containing 24 OS2 single-mode fibers with two 12-fiber MPO connectors at both ends. This fiber cable assembly plugs into the back of a breakout cassette that splits the 24 fibers into 12 LC Duplex connectors at the front of the cassette.

MPO cassette has duplex lc connector and MTP connector

Four of these cassettes are mounted in a one rack unit (1U) patch panel to provide up to forty-eight 10G equipment connections using LC Duplex patch cords. The FS.COM FHD 1U fiber enclosure with four LC Duplex cassettes is illustrated in Figure below.

1U fiber enclosure with four LC Duplex cassettes

If upgrading from 10G to 40G, one or more of the LC duplex cassette(s) can be replaced with 12 port MPO adapters. The MPO adapters are designed to fit in the same opening as the cassettes. The Figure below illustrates the case where all four cassettes are replaced with four high density 12 port MPO adapters. This solution illustrates an upgrade path from 10G to 40G that does not require any additional space and reuses the same patch panels. The 12 LC duplex cassette(s) are replaced with 12 port MPO adapter(s) as needed. Additional 24-fiber cable assemblies (or any fiber counts in multiples of 12 fibers) are provided as needed for backbone or horizontal cabling.

1U fiber enclosure with four MPO adapter

How To Test Optical Loss with Light Source and Power Meter?

In order to know how effectively your fiber optic cables are transmitting, you’ll need to test each one for optical loss. The term “optical loss” can also be called insertion loss, describes the difference between the amount of light sent into the transmitting end of a fiber optic cable, and the amount of light that successfully makes it to the cable’s receiving end. TIA-standards specify that you must measure optical loss using an optical power meter and the proper light source to certify an optical fiber cable. How to do that? This blog will tell you.

Introduction to light source
A light source is a device that provides a continuous wave (CW) and stable source of energy for attenuation measurements. It includes a source, either an LED or laser, that is stabilized using an automatic gain control mechanism. LEDs are typically used for multimode fiber. On the other hand, lasers are used for singlemode fiber applications.

Introduction to light source
The output of light from either an LED or laser source may also have the option of modulation (or chopping) at a given frequency. The power meter can then be set to detect this frequency. This method improves ambient light rejection. In this case, a 2 kHz modulated light source can be used with certain types of detectors to tone the fiber for fiber identification or for confirmation of continuity.

Introduction to power meter
The power meter is the standard tester in a typical fiber optic technician’s toolkit. It is an invaluable tool during installation and restoration. The power meter’s main function is to display the incident power on the photodiode.

Introduction to power meter
Transmitted and received optical power is only measured with an optical power meter. Optical loss must be measured with a light source. Connect one end of the fiber to the light source and the other end to the power meter. The light source sends a wavelength of light down the fiber. At the other end of the cable, the power meter reads that light, and determines the amount of signal loss.

Introduction to Testing Procedure

  • Connect the light source to the transmitting end of the test cable.
  • Connect the power meter to the receiving end of the test cable.
  • Turn on the source and select the wavelength you want for the loss test.
  • Turn on the meter, select the “dBm” or “dB” range and select the wavelength you want for the loss test.
  • Measure the power and loss at the meter.

Light Source and Power Meter

Cables with losses higher than 0.5 dB per end should be cleaned and retested. Dirt is always an issue. If any of the connectors are dirty, measurements will show higher loss and more variability. If the optical loss is still higher than 0.5 dB after cleaning, that means this cable is unqualified. Then you can discard it.

What Are the Advantages and Disadvantages of Optical Fiber Cable?

An optical fiber or fiber optic cable is a flexible, transparent fiber made by drawing glass, which are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data rates) than wire cables. Whether should I use optical fiber cables in my network? What are the advantages and disadvantages of optical fiber?


Advantages of Optical Fiber Cable

  • Bandwidth

Fiber optic cables have a much greater bandwidth than metal cables. The amount of information that can be transmitted per unit time of fiber over other transmission media is its most significant advantage.

  • Low Power Loss

An optical fiber offers low power loss, which allows for longer transmission distances. In comparison to copper, in a network, the longest recommended copper distance is 100m while with fiber, it is 2km.

  • Interference

Fiber optic cables are immune to electromagnetic interference. It can also be run in electrically noisy environments without concern as electrical noise will not affect fiber.

  • Size

In comparison to copper, a fiber optic cable has nearly 4.5 times as much capacity as the wire cable has and a cross sectional area that is 30 times less.

  • Weight

Fiber optic cables are much thinner and lighter than metal wires. They also occupy less space with cables of the same information capacity.  Lighter weight makes fiber easier to install.

  • Security

Optical fibers are difficult to tap. As they do not radiate electromagnetic energy, emissions cannot be intercepted. As physically tapping the fiber takes great skill to do undetected, fiber is the most secure medium available for carrying sensitive data.

  • Flexibility

An optical fiber has greater tensile strength than copper or steel fibers of the same diameter. It is flexible, bends easily and resists most corrosive elements that attack copper cable.

  • Cost

The raw materials for glass are plentiful, unlike copper. This means glass can be made more cheaply than copper.

Disadvantages of Optical Fiber Cable

  • Difficult to Splice

The optical fibers are difficult to splice, and there are loss of the light in the fiber due to scattering. They have limited physical arc of cables. If you bend them too much, they will break.

  • Expensive to Install

The optical fibers are more expensive to install, and they have to be installed by the specialists. They are not as robust as the wires. Special test equipment is often required to the optical fiber.

  • Highly Susceptible

The fiber optic cable is a small and compact cable, and it is highly susceptible to becoming cut or damaged during installation or construction activities. The fiber optic cables can provide tremendous data transmission capabilities. So, when the fiber optic cabling is chosen as the transmission medium, it is necessary to address restoration, backup and survivability.

  • Can’t Be Curved

The transmission on the optical fiber requires repeating at distance intervals. The fibers can be broken or have transmission losses when wrapped around curves of only a few centimeters radius.

Fiber optic cable has both advantages and disadvantages. However, in the long run, optical fiber will replace copper. In today’s network, fiber optic cable becomes more popular than before and is widely used. FS.COM, as a leading optics supplier, provides all kinds of optical fiber cables with high quality and low price for your option.

100G Optical Transceivers Links: PSM4 vs CWDM4

In the past few years, 100G optical transceivers are become more popular and widely used than before. The most common 100G optical transceivers we use today are CFP, CFP2, CFP4 and QSFP28, especially the QSFP28. Besides 100G optical transceivers links (-SR10, SR4, -LR4) defined by IEEE standard, Multi-Source Agreement (MSA) also defines two 100G optical transceivers links: PSM4 and CWDM4. Both PSM4 and CWDM4 architectures take the 100GE signal and carry it over 4 separate channels. So, what’s the difference between them? PSM4 vs CWDM4–difference between them will be introduced in this blog.

The 100G PSM4 Specification defines requirements for a point-to-point 100 Gb/s link over eight single mode fibers (4 transmit and 4 receive) up to at least 500 m, each transmitting at 25Gbps. Four identical and independent lanes are used for each signal direction (as shown in figure below). Therefore, two transceivers communicate usually over 8-fiber MTP/MPO single mode patch cords. PSM4 is limited to 500 m. At present, PSM4 links are usually used in 100G QSFP28 optical transceivers.

100G Optical Transceivers Links PSM4

Similar to PSM4, CWDM4 also uses 4 x 25 Gbps to achieve 100 Gbps. But unlike PSM4, CWDM4 uses an optical multiplexer and de-multiplexer to reduce the number of fibers to 2 (as shown in figure below). Therefore, we only need to use a duplex single mode fibers to connect two 100G CWDM4 optical transceivers modules. CWDM4 is limited to 2 km. At present, CWDM4 links are used in both 100G CFP4 or the QSFP28 optical transceivers.

100G Optical Transceivers Links CWDM4

100G Optical Transceivers Links: PSM4 vs CWDM4
A summary table comparing the key differences between CWDM4 and PSM4 is shown below. From an optical transceiver module structure viewpoint, PSM4 can be more cost effective because it uses a single uncooled CW laser which splits its output power into four integrated silicon modulators. However, from an infrastructure viewpoint, PSM4 would be more expensive when the link distance is long, mainly due to the fact that PSM4 uses 8 optical single-mode-fibers while CWDM4 uses only 2 optical single-mode-fibers.

100G Optical Transceivers Links PSM4 vs CWDM4
When considering the above two factors, a total cost comparison can be qualitatively shown in the figure below. As can be seen in the figure, PSM4 starts with a lower cost due to its lower transceiver cost, but as the link distance increases, its total cost climbs up very fast due to the fact that it uses 8 optical fibers.

100G links PSM4 vs CWDM4

Different companies have different opinions on what the link distance is at the crossing point, and what the transceiver cost difference is at zero distance. But based on the specifications of PSM4 MSA, the technology has to be limited to 500 meters, which can actually cover the majority of today’s data center needs. FS.COM provides both 100G PSM4 QSFP28 ($ 750.00) and 100G CWDM4 QSFP28 ($ 1350.00) optical transceivers for your options.

Do You Use QSFP+ Direct-Attach Twinax Copper Cable?

To achieve a 40G network connection, we usually use QSFP+ transceiver modules and MTP patch cords, which can help transmit 150 m to 40 km. But, if we only need to connect within 10 m, we can use QSFP+ direct-attach twinax copper cables. It’s a high-speed, cost-effective alternative to QSFP+ fiber optics. What’s QSFP+ direct-attach copper (DAC)? Whether should I use it? This blog will introduce the knowledge of QSFP+ DAC to you.

What Is QSFP+ Direct-Attach Twinax Copper Cable?
QSFP+ DAC is also called QSFP+ to QSFP+ cable. It has a QSFP+ module at one end and another QSFP+ module at the other end, and uses integrated duplex serial data links for bidirectional communication. Used to connect the 40 Gbps QSFP+ port of a switch at one end to another QSFP+ port of a switch at the other end, it can provide high quality of 40G end-to-end connection. Usually, maximum transmission distance of QSFP+ DAC is 10 m, which makes these cables are suitable for in-rack connections between servers and Top-of-Rack (ToR) switches. Besides, since its price ($30-$200) is much lower than QSFP+ optics, it’s a more cost-effective option to connect within racks and across adjacent racks.


Passive vs Active QSFP+ DAC
QSFP+ direct-attach twinax copper cable comes in either an active or passive twinax (twinaxial) and connects directly into a QSFP+ housing. An active twinax cable has active electronic components in the QSFP+ housing to improve the signal quality. A passive twinax cable is mainly just a straight “wire” and contains few components. Generally, twinax cables shorter than 5 meters are passive and those longer than 5 meters are active, but this may vary from vendor to vendor. QSFP+ direct-attach copper is a popular choice for 40G Ethernet reaches up to 10 m due to low latency and low cost.

Popular QSFP+ Cable Overview
At present, major QSFP+ DAC vendors are Brocade, Arista and Cisco. We can use QSFP+ DAC in their hardware with QSFP+ interfaces. Although the transmission distance of QSFP+ DAC can reach 10 m, the most common types we use are 1 m, 3 m, and 5m. In the market, popular QSFP+ DAC includes Brocade 1m(40G-QSFP-C-0101) , 3m(40G-QSFP-C-0301) and 5m(40G-QSFP-C-0501) passive QSFP+ twinax copper, Arista 1m(CAB-Q-Q-1M) and 3m(CAB-Q-Q-3M) passive QSFP+ twinax copper, and Cisco 1m(QSFP-H40G-CU1M) and 3m(QSFP-H40G-CU3M) passive QSFP+ twinax copper.

Brocade,Arista and Cisco DAC

40 Gbps Direct-Attached QSFP+ to QSFP+ Copper Cables (1 m, 3 m, 5 m) are optimized to fully leverage 40 Gigabit Ethernet (GbE) switches and routers. FS.COM provides a wide range of QSFP+ cable assembly options for your network connection, which satisfies the need for ultra-thin, light-weight, highly flexible cabling solutions for use in high density intra-rack applications.

How to Convert a QSFP+ Port to a SFP+ Port?

As data communications technology migrates from 10GbE to 40GbE and beyond, it is often necessary to connect 40GbE equipment with existing 10GbE equipment. As we know 40GbE NIC or switch usually equipped with QSFP+ ports, and 10GbE switch usually equipped with SFP+ ports. That is to say we must know how to convert a QSFP+ port to a SFP+ port. At present, there exists three ways to solve this problem. I will explain it in this blog.

QSFP+ to SFP+ Cable
As shown in the figure below, a QSFP+ to SFP+ cable consists of a QSFP+ transceiver on one end and four SFP+ transceivers on the other end. The QSFP+ transceiver connects directly into the QSFP+ access port on the switch. The cables use high-performance integrated duplex serial data links for bidirectional communication on four links simultaneously. The SFP+ links are designed for data rates up to 10 Gbps each. QSFP+ cable is available in passive and active two types. Passive QSFP+ cable has no signal amplification built into the cable assembly, therefore, their transmission distance is usually shorter than an active one.


QSFP+ to SFP+ Adapter (QSA)
You can convert a QSFP+ port to a SFP+ port using the QSFP+ to SFP+ adapter. QSA provides smooth connectivity between devices that use 40G QSFP+ ports and 10G SFP+ ports. Using this adapter, you can effectively use a QSFP+ module to connect to a lower-end switch or server that uses a SFP+ based module. This adapter is very easy to use. As shown in the figure below, just plug one side of the QSA in your QSFP+ port, and plug a SFP+ module into another side of the QSA. Then you can convert a QSFP+ port to a SFP+ port easily.


QSFP+ Breakout Cable
As we know, parallel 40GBASE-SR4 QSFP+ modules use 8 out of 12 MPO/MTP interface fibers transmitting 4 x duplex (DX) channels (4 x transmit and 4 x receive). The QSFP+ breakout cable uses a pinless MTP connector on one end for interfacing with the QSFP port on the switch. The other end contains 4 duplex LC connectors, which provide connectivity to the SFP+ ports on the switch. Thus higher-speed equipment (40G QSFP+) can be connected to slower-speed equipment (10G SFP+) successfully.

QSFP+ Breakout Cable convert qsfp+ to sfp+

When you want to connect a QSFP+ port to a SFP+ port, you can use QSFP+ to SFP+ cable, QSFP+ to SFP+ adapter or QSFP+ breakout cable. All these three options can meet your needs. FS.COM provides a full range of compatible QSFP+ cable, which can be 100% compatible with your Cisco, Juniper, Arista and Brocade switches and routers. Or you want to use QSFP+ breakout cable, you can also find it in our Fiberstore.

Considerations for Buying Compatible Optical Transceiver

When choosing compatible optical transceiver, nearly 90% of transceiver end users may worry about their quality and compatibility. As we know, the price of compatible optical transceiver is usually much lower than original-brand transceiver. So, can compatible optical transceiver really perform well as the original one? What should I pay attention to when buying compatible optical transceiver? This blog will give you some practical advice aimed to help you choose compatible optical transceiver with high compatibility and low cost.

Main Concerns for Buying Compatible Optical Transceiver

  • Compatibility – The transceiver can’t be compatible with your original-brand switch.
  • Life Span – The quality of the transceiver is not reliable and the service life is short.
  • Poor performance – High latency etc.
  • Others – Refurbished modules, power consumption etc.


How to Ensure Quality of Compatible Optical Transceiver?

1. Professional Testing Process
Make sure the compatible optical transceiver you buy is tested on relevant original-brand switch. For example, when you buy a Cisco compatible optical transceiver, make sure it’s tested on Cisco switches. Usually, the compatible optical transceiver that has been tested can always guarantee perfect performance in your network.

2.Guaranteed Warranty Policy
The shopping experience tells us that bad quality products usually have short-term warranties. If there’s something wrong with your products, the vendor won’t give you any maintenance and return service. Instead, if the warranty time is long such as lifetime warranty, the products’ quality may be more reliable and stable.

3.Reputable Brand Vendor
With strict quality control system and OEM experience for many years, reputable brand vendors can usually guarantee a reliable and stable connectivity for your high-speed fiber transmission system. All the raw materials they used are safe and the performance can be comparable with the original.

Reliable Compatible Optical Transceiver Structure Details
Besides the considerations mentioned above, knowing the structure details requirement of a good compatible optical transceiver may also help you a lot.

1.Premium Metal Housing
A good transceiver module is made of premium pluggable hard gold plating, which can ensure repeated plugging and unplugging. In addition, by strict control of the gold plating thickness, it can reach a superior quality and ensure excellent connection as well as reducing the working temperature.


2.High-Quality Laser
The high-quality laser is with high sensitivity, low attenuation and high quality which ensure the perfect signal transmitting and receiving.


3.Advanced Chip
The advanced chip offers the high performance and low power consumption to the module solution which ensures the signal to be transmitted with high speed and stable performance.


4.Perfect Combination
The combination of the gold-finger (conductive metal), chip and metal housing makes a perfect transceiver module.


When you’re looking to upgrade your network, it makes sense to choose a compatible optical transceiver to help save cost. Fiberstore, a professional manufacturer and supplier of compatible optical transceiver, may be your ideal choice. Each transceiver module from FS.COM is tested on the real working environment before shipping which ensures the reliable and stable performance. Besides, Fiberstore offers a 60-day money-back return policy and a guaranteed warranty policy to ensure their transceivers’ quality. If you try to use them, you may like them.

Wireless Access Point vs Router–Which One Is Right for You?

Nowadays wireless networks are almost at every home. And surely you hear people around talking about wireless equipment from time to time. Among, wireless router is the most familiar one in our lives. However, we’ve heard more and more about the word “wireless access point” or “AP” recently. What’s the wireless AP? Is it the same as the wireless router? What’s the difference between them? Wireless access point vs router: difference between them will be introduced in this blog.

What Is a Router?
Most anyone who has a Internet connection has a router. Router is a device that routes packets between different networks. A typical consumer router is a wireless router and it has two network interfaces: LAN (including WLAN) and WAN. It serves to connect a local area network (LAN) to a wide area network – Internet (WAN). That is to say if we want to connect to Internet, we must use a router. Routers on the other hand can manage an entire home or small business giving network capability to many computers and devices simultaneously, either wired or wirelessly (when wireless router used).


What Is a Wireless Access Point?
As for wireless access point (AP), it’s commonly wire connected to Ethernet network’s router, hub or switch and then to create a simple wireless network. This was done by using a Ethernet cable to connect a switch and a AP and the AP would then communicate with WiFi devices and giving them network access. Wireless access point does not route anything. It just converts an existing wired network (LAN) into a wireless one (WLAN). A router can be a access point but a access point can’t be a router.


Wireless Access Point vs Router: Which One should I Buy?
Before routers became standard with built in WiFi, we must use a wireless AP to connect wireless devices to our network. However, now that most any router has built in WiFi and plays many roles including being a AP, many don’t use dedicated AP as they have in the past. Then wireless routers are common place in any network today but often there are weak WiFi signals or dead spots in any network. A wireless access point can be added in locations that have bad wireless network ability help with WiFi dead spots and extending a wireless network.

Wireless Access Point vs Router

In conclusion, if you want build more reliable wireless network, you may need a wireless access point. If you just want wireless network at home to cover only several people, the wireless router is enough. Today’s wireless AP is widely used in business and larger hotspot WLANs to cover a bigger area or to support hundreds of users. In larger WLANs, it usually makes sense to have several APs feeding into a single, separate router. FS.COM provides several wireless access points with high performance to support resilient wireless access services for use in enterprise offices, schools, hospitals, hotels and more.


5 Concepts Help Easily Get WDM System

The Wavelength Division Multiplexing (WDM) system is a passive, optical solution for increasing the flexibility and capacity of existing fiber lines in high-speed networks. By adding more channels onto available fibers, the WDM System enables greater versatility for data communications in ring, point-to-point, and multi-point topologies for both enterprise and metro applications. Do you know about WDM system? 5 concepts provided in this blog may help you easily get it.

Optical Transmission
Optical transmission is the conversion of a digital stream of information to light pulses. The light pulses are generated by a laser source (LED or vessel) and transmitted over an optical fiber. The receiver converts the light pulses back to digital information.

Optical Transmission

Wavelength Division Multiplexing
WDM is based on the fact that optical fibers can carry more than one wavelength at the same time. The lasers are transmitting the light pulses at different wavelengths that are combined via filters to one single output fiber. The device used to combine wavelengths is called multiplexer and the device used to separate wavelengths is called demultiplexer, which are the two most basic component in WDM system.

Wavelength Division Multiplexing

Optical Amplifiers
An optical amplifier is a device that amplifies an optical signal directly, without the need to first convert it to an electrical signal. Optical amplifiers boosts the attenuated wavelengths and are more cost efficient than electrical repeaters. Without amplifiers the reach is limited to 80-100km before electrical regeneration. Amplifier stations typically each 80-100km.

Depending on signal types and fiber characteristics, amplifiers are used in DWDM networks and increases the reach of the optical signals up to 3000 km. Amplifiers are an basic building block for a powerful DWDM network.

Optical Amplifiers

Transponders provides wavelength conversion from client to WDM signal. A transponder maps a single client to a single WDM wavelength. The digital framing of a line signal from a transponder provides service monitoring, management connectivity and increased reach. The broad range of available transponders enables cost efficient solutions for both CWDM & DWDM.


Optical Add Drop Multiplexer
The main function of an optical multiplexer is to couple two or more wavelengths into the same fiber. If a demultiplexer is placed and properly aligned back-to-back with a multiplexer, it is clear that in the area between them, two individual wavelengths exist. This presents an opportunity for an enhanced function, one in which individual wavelengths could be removed and also inserted. Such a function would be called an Optical Add Drop Multiplexer (OADM). OADM is used for increased flexibility in the optical paths. Services can be redirected upon failure or capacity constraints and capacity can be increased dynamically per node.


Multiplexer and demultiplexer are the most basic component in WDM system. If your transmission distance is more than 100 km, an optical amplifier is necessary. If your client wavelength isn’t available for WDM applications, you may need a transponder to convert it to WDM available wavelength. Want to achieve a more flexible, just choose to use a OADM. Besides these, sometimes, a dispersion compensation module is also needed to fix the form of optical signals that are deformed by chromatic dispersion and compensates for chromatic dispersion in fiber that causes the light pulses to spread and generate signal impairment. Do you get WDM system? Just start to build your own WDM system now!

Difference Between Straight-Through and Crossover Cable

Ethernet cables can be wired as straight-through or crossover. The straight-through is the most common type and is used to connect computers to hubs or switches. They are most likely what you will find when you go to your local computer store and buy a patch cable. Crossover cables are more commonly used to connect a computer to a computer and may be a little harder to find since they aren’t used nearly as much as straight-through cable. Then, what’s the difference between them? Difference between straight-through and crossover cables will be introduced in this blog.

T568A And T568B Wiring Standard Basis
A RJ45 connector is a modular 8 position, 8 pin connector used for terminating Cat5e or Cat6 twisted pair cable. A pinout is a specific arrangement of wires that dictate how the connector is terminated. There are two standards recognized by ANSI, TIA and EIA for wiring Ethernet cables. The first is the T568A wiring standard and the second is T568B. T568B has surpassed 568A and is seen as the default wiring scheme for twisted pair structured cabling. If you are unsure of which to use, choose 568B.


What Is Straight-Through Cable?
A straight-through cable is a type of twisted pair cable that is used in local area networks to connect a computer to a network hub such as a router. This type of cable is also sometimes called a patch cable and is an alternative to wireless connections where one or more computers access a router through a wireless signal. On a straight-through cable, the wired pins match. Straight-through cable use one wiring standard: both ends use T568A wiring standard or both ends use T568B wiring standard. The following figure shows a straight-through cable of which both ends are wired as the T568B standard.


What Is Crossover Cable?
An Ethernet crossover cable is a type of Ethernet cable used to connect computing devices together directly. Unlike straight-through cable, crossover cables use two different wiring standards: one end uses the T568A wiring standard, and the other end uses the T568B wiring standard. The internal wiring of Ethernet crossover cables reverses the transmit and receive signals. It is most often used to connect two devices of the same type: e.g. two computers (via network interface controller) or two switches to each other.

Crossover Cable

Choose a Straight-Through or Crossover Cable?
Usually, straight-through cables are primarily used for connecting unlike devices. And crossover cables are use for connecting unlike devices alike devices.
Use straight-through cable for the following cabling:

  • Switch to router
  • Switch to PC or server
  • Hub to PC or server

Use crossover cables for the following cabling:

  • Switch to switch
  • Switch to hub
  • Hub to hub
  • Router to router
  • Router Ethernet port to PC NIC
  • PC to PC


Straight-through and crossover cables are wired differently from each other. One easy way to tell what you have is to look at the order of the colored wires inside the RJ45 connector. If the order of the wires is the same on both ends, then you have a straight-through cable. If not, then it’s most likely a crossover cable or was wired wrong. At present, the straight-through cable is much more popular than crossover cable and is widely used by people. FS.COM provides a full range straight-through Cat5e, Cat6, Cat6a and Cat7 Ethernet patch cables with many lengths and colors options. Look for Ethernet patch cables, just come to FS.COM!