Which Tight Buffered Fiber Distribution Cable Fits Your Application?

Optical fibers with fiber counts ranging from 2 to 144 counts or more are usually coated together inside a single strand of fiber optic cable for better protection and cabling. Multi-fiber optic cables are usually required to pass a lot of distribution points. And each individual optical fiber should connect only one specific optical interface via splicing or terminating by connectors. Thus, fiber optic cables used for distribution should be durable and easy to be terminated. Tight buffered fiber distribution cables, which meet these demands, are widely used in today’s indoor and outdoor applications, like data center and FTTH projects. This post will introduce tight buffered fiber distribution cables.

tight buffered fiber cable

The Beauty of 900um Tight Buffered Fibers

Most of tight buffered fiber distribution cables are designed with 900um tight buffered fibers. This is decided by its applications. As the above mentioned, the distribution cable should be durable and easy to be terminated. The following picture shows the difference between 250um bare fiber and 900um tight buffered fiber. They are alike, but the tight buffered fiber has an additional buffer layer. Compared with bare fibers, 900um tight buffered fibers can provide better protection for the fiber cores. 900um tight buffered fibers are easy to be stripped for splicing and termination. In addition, tight buffered fiber cables are usually small in package and flexible during cabling. These are the main reasons why a lot of fiber optic distribution cables use tight buffered design.

250um vs 950um

Choose Tight Buffered Distribution Fiber Cables According to Applications

900nm tight buffered distribution fiber cables also come in a variety of types. Tight buffered distribution fiber cables used for different environments and applications might have different fiber types, outer jackets and cable structures. The following will introduce several tight buffered distribution fiber cables for your reference.

unitized distribution fiber cable
Indoor Tight Buffered Distribution Fiber Cable

Tight buffered distribution fiber cables used for indoor applications are usually used for intra building backbones and routing between telecommunication rooms. Large tight buffered fiber cable with fiber counts more than 36 fibers generally has “sub-unit” (unitized) design (shown in the above). While smaller tight buffered distribution cables, with fiber counts of 6, 12 or 24, usually have “single-jacket” (non-unitized) designs, which are more flexible in cabling and have much smaller packages and cost advantages. The lower count tight buffered distribution fiber cables with color coded 12 fibers and 24 fibers are very popular. The following picture shows a 24-fiber indoor tight buffered distribution fiber cable with single-jacket design.

24-fiber tight buffered fiber cable

During practical use, these 6, 12 or 24-fiber indoor tight buffered distribution fiber cables can be spliced with other fibers or be terminated with fiber optic connectors. And they can be made into multi-fiber optic pigtails or fiber patch cable after terminated with fiber optic connector on one end or two end. The color coded fibers can also ease fiber cabling.

Indoor/Outdoor Armored Tight Buffered Distribtight buffered fiber terminationution Fiber Cable

Although tight buffered distribution fiber cables are usually used for indoor applications, there is still a place for them in outdoor applications after added with a layer of metal armored tube inside the cable. Armored fiber cables are durable, rodent-proof, water proof and can be directly buried underground during installation, which saves a lot of time and money.

Armored tight buffered distribution fiber cable

Here we strongly recommend a low fiber count armored tight buffered distribution fiber cable which can be used for both indoor and outdoor applications (show in the above picture). This low fiber count armored tight buffered cable has a single-jacket design with a steel armored tape inside the cable. It can be used for both backbone cabling and horizontal cabling in indoor environments. And it can also be used for direct buried applications and aerial application in outdoor environments.

FS.COM Same Day Shipping Tight Buffered Distribution Fiber Cables Solution

During the purchasing of fiber optic cables, one of the most important thing is the shipment of fiber cables. Many bulk fiber cables are transmitted via shipping, which might take a long time. Now FS.COM customers in the USA can enjoy same day shipping for tight buffered distribution fiber cables for both indoor and outdoor applications. Details are shown in the following table. Kindly contact sales@fs.com for more details, if you are interested.

Part No. Description
31909 12 Fibers OM3 Plenum, FRP Strength Member, Non-unitized, Tight-Buffered Distribution Indoor Fiber Optical Cable GJPFJV
31922 12 Fibers OM4 Plenum, FRP Strength Member, Non-unitized, Tight-Buffered Distribution Indoor Fiber Optical Cable GJPFJV
31866 24 Fibers OM4 Riser, FRP Strength Member, Non-unitized, Tight-Buffered Distribution Indoor Fiber Optical Cable GJPFJV
51308 24 Fibers OS2, LSZH, Single-Armored Double-Jacket, Tight-Buffered Distribution Waterproof Indoor/Outdoor Cable GJFZY53

Source: http://www.fs.com/blog/tight-buffered-fiber-distribution-cables-for-indoor-and-outdoor-use.html

100G QSFP28 Fiber Optic Modules and Standards

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

100G QSFP28

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

100Gbase-SR4 QSFP28

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

100Gbase-LR4 QSFP28

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

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

100Gbase-PSM4 QSFP28

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

100Gbase-CWDM4 QSFP2

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


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

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

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

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

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


Transmission Mode

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

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

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


Cabling Structure

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

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

The above table listed the basic information of the three modules for your referent. 100G-QSFP-SR4 are suitable for short distance transmission over OM3 or OM4 fiber using 12-MTP fiber cabling system. 100G-QSFP-PSM4 also has a 12-fiber MTP interface but it can support a transmission distance up to 500m over SMF. 100G-QSFP-LR4 is suitable for long transmission distance up to 2km over two single-mode fibers. If you are interested in more 100G QSFP28 modules, kindly click the following page: 100G Transceiver.

Overcome OTDR Dead Zone With Launch Fiber

OTDR is a popular fiber optic testing tool which can be used to test the fiber loss, and locate the faults in fiber optic links. However, the OTDR dead zone will affect the testing result and the application of OTDR. To overcome OTDR dead zone during fiber optic testing, launch fiber is being added between OTDR and optical fiber link under test. OTDR launch fiber comes in different types of packages. OTDR launch box and OTDR launch fiber ring are the most commonly used launch fibers.

Why Can Launch Fiber Overcome OTDR Dead Zone?

OTDR insert pulses of light into fiber optic link and measure the back reflection caused by fiber faults to locate the faults. If a long fiber link is required to be tested, a lot of optical power should be inserted into the optical fiber to make sure that the light can be seen at the other end. If powerful optical pulses are inserted into optical fiber, pulse width of the launched optical signal will be increased, which will cause the dead zone at a length of fiber and affect the testing result of OTDR. This dead zone might be hundreds or thousands meters long.

OTDR launch box

To minimize the affection of the OTDR dead zone during fiber optic testing. A length of long enough optical fiber is being added between the OTDR and the fiber under test. In this way, the OTDR dead zone will happen in this additional optical fiber. The launch fiber is actually a length of optical fiber which is long enough to cover the OTDR dead zone to increase the testing accuracy. Launch fiber is usually terminated with a connector on each end to connect the OTDR with the fiber link under test.

launch fiber

OTDR Test With Launch Fiber

OTDR launch fiber mainly has two designs, one is fiber ring design and the other is box design, separately known as launch fiber ring and OTDR launch box or OTDR dead zone box. The using of them is generally the same. Here offer two situations about how to use OTDR launch fiber.

OTDR testing with launch fiber

In some cables, launch cable is being used to cover the dead zone at the beginning of the fiber link. In these cases, OTDR launch fiber or OTDR launch box is deployed between the OTDR and the near end connection as shown in the above picture. This allows the accurate measurement of the fiber loss at the near end connection.

OTDR and launch fiber

In some cases, the fiber loss at the far end connection should also be tested. Then, the launch fiber can be installed added at the far end connection to work as a receive cable, as shown in the above picture.

Please note that the launch fiber you used for testing should have the same fiber types (OS2, OM1, OM2, OM3, OM4) as the optical fiber under test.


Using launch fiber to overcome OTDR dead zone is the choice in most cases, especially for long optical fiber testing. Let the OTDR dead zone occur in the launch cable to ensure the accurate testing result. Launch fiber is suggested to be added at the beginning and the end of the fiber optic link, if the light loss of the whole fiber link is required. If you want to need more specific details about OTDR launch box, kindly visit another article: Why Do You Need OTDR Launch Box

PoE in Enterprise Network

In traditional data communication network, a network connection and a power connection are required. However, with PoE technology, only the ordinary Ethernet network cable is required. PoE (Power over Ethernet) is a technology designed to allow the existing Ethernet network cable to deliver direct electrical current flows. It has a lot of advantages like lower cost, easier maintenance, less down time and great flexibility during management and network installation. A variety of products have been designed to make full use of PoE technology. This post will introduce these PoE based products and how to use them in our network.

PoE switch

PoE switch is the most important device is you are going to use PoE technology. It is the PoE switch that transmission the necessary data and power flow together to other PoE devices. Not all the devices can be powered by PoE switches, as the electrical power provided by a PoE switches is limited. For instance, the IEEE 802.3af guarantees only 12.95 W of power on a given connection. Thus, if your devices required power higher than that, then the PoE cannot work out under this standard. The power that a PoE can provide for connections differs according to the technologies. And the port type and port numbers that PoE switches provided are various. Generally, PoE switches provided in the market can provide SFP ports for uplink and RJ45 ports for downlink. Here offers several different PoE

PoE Switch Port Detail Power Supply for PoE Port Max. Power Consumption
PS130W-8 8 PoE ports, 2 SFP ports 15.4W 130W
PS250W-8 8 PoE ports, 2 SFP ports 30W 250W
PS400W-24 24 PoE ports, 4 SFP ports 15.4W 400W
PS650W-24 24 PoE ports, 4 SFP ports 30W 650W
PS650W-48 48 PoE ports, 4 SFP+ ports 30W 350W

In many public places or even our own houses, camera is installed for surveillance These cameras are usually required to be connected to the Ethernet or monitor. As the power required by camera is not high and the places they deployed are usually lack of power outlet, IP camera which supports PoE is very popular. With a RJ45 port, the PoE IP Camera can be connected to the switch for data communication. The following picture shows a Camera that support both Ethernet network cable and additional power cords.

PoE IP Camera

WiFi is necessary in most places now. In the public places like hospital, hotel, or office, wireless access points are usually installed to transfer the data from Ethernet network cable into WiFi signals. Wireless access point is usually installed on the ceiling, where power outlet seldom installed. Thus, PoE wireless access pointer is a preferred choice in most public places. As wireless access point just needs low voltage power support, the network cable is able to provide enough power that it required.

PoE wireless access point

Network Making Full Use of PoE technology

Telecommunication network using PoE technology has a wide range of applications. It is usually installed at enterprise network like office building. The following picture shows a sample of small network using PoE technology.

PoE network

An 8-port PoE switch is being used to connect devices in a small office. The eight ports of PoE switch are set into support four Non-PoE ports and four PoE port. The devices like laptop and printer required high voltage power supply is connected to the non-PoE ports for data communication. Devices like 300 Mbps wireless access point with PoE function, and two PoE IP cameras that requires low voltage power supply, are connected to PoE port of this switch for both power supply and data communication.

The using of PoE switch, camera, and wireless access point is flexible and convenience. To provide higher speed data transmission and more applications is the trend of PoE devices developing. Meanwhile, the power that these PoE switch can supply is also increasing gradually.