Multifiber MTP/MPO cable is a preferable choice for high-density telecom and datacom cabling. For the outer jacket of MTP/MPO cable, there are many terms to describe it, such as CM, LSZH, CMP, CMR, PVC, etc. FS.COM carries several of these technologies. Do you know the differences between them? And what are the characteristics of each type? Most importantly, which one do you need for the task? This post will introduce some major jacket types for MTP/MPO cable and the other acronyms for communication cable ratings.

MTP cabling

Figure 1: MTP/MPO cabling.


CMP (plenum-rated) MTP/MPO cable complies the IEC (International Electrotechnical Commission) 60332-1 flammability standard. CMP MTP/MPO cable is designed to be used in plenum spaces, where air circulation for heating and air conditioning systems can be facilitated, by providing pathways for either heated/conditioned or return airflows. Typical plenum spaces are between the structural ceiling and the drop ceiling or under a raised floor. CMP rated communication cable is suitable for telephone and computer network exactly for this matter. It is designed to restrict flame propagation no more than five feet, and to limit the amount of smoke emitted during fire. Additionally, CMP MTP/MPO cable is more fire-retardant than LSZH, and as a result, sites are better protected. As an excellent performer cable, it is usually more costly than other cable types.

It has to be noted that some CMP cable made of fluorinated ethylene polymer (FEP) still has shortcomings of potential toxicity. Thus better CMP cable with a non-halogen plenum compound is further produced. For safety reason, no high-voltage equipment is allowed in plenum space because presence of fresh air can greatly increase danger of rapid flame spreading if the equipment catch on fire.


The LSZH (low smoke zero halogen, also refers to LSOH or LS0H or LSFH or OHLS) has no exact IEC code equivalent. The LSZH cable is based on the compliance of IEC 60754 and IEC 61034. LSZH MTP/MPO cable is better than other cables in been safer to people during a fire. It has no halogens in its composition and thus does not produce a dangerous gas/acid combination when exposed to flame. LSZH cable reduces the amount of toxic and corrosive gas emitted during inflammation. LSZH MTP/MPO cables are suitable to be used in places that is poorly aired such as aircraft, rail cars or ships, to provide better protection to people and equipment. LSZH MTP/MPO cable is more widely applied type than other materials, both for its secure properties and lower cost than CMP.

Other Types

The cable jackets will be discussed in the following part are not as frequently used for MTP/MPO cable as CMP and LSZH.

CMR (riser-rated) complies IEC 60332-3 standards. CMR cable is constructed to prevent fires from spreading floor to floor in vertical installations. It can be used when cables need to be run between floors through risers or vertical shafts. PVC is most often associated with riser-rated cable, but nor all PVC cable is necessarily riser-rated; FEP is most often associated with CMP. Since the fire requirements for CMR cable is not that strict, CMP cable can always replace CMR cable, but not reversibly.

CM (in-wall rated) cable is a general purpose type, which is used in cases where the fire code does not place any restrictions on cable type. Some examples are home or office environments for CPU to monitor connections.

The figure below generally illustrates the applicable environments for CMP, CMR and CM rated cables.

CMP, CMR, CM cable application

Figure 2: CMP, CMR, CM cable application.


Knowing the relevant details of cable ratings of MTP/MPO will certainly help in selecting the best one for your applications, which is as important as other factors. FS.COM provides high quality plenum and LSZH MTP/MPO trunk cables and MTP breakout cables at affordable prices.

Which Fiber Loopback Should I Use for My Transceiver?

In telecommunication, fiber loopback is a hardware designed to provide a media of return patch for a fiber optic signal, which is typically used for fiber optic testing or network restorations. When we need to know whether our fiber optic transceiver is working perfectly, we can use a fiber loopback cable as an economic way to check and ensure it. Basically, the loopback aids in debugging the physical connection problem of the transceiver by directly routing the laser signal from the transmitter port back to the receiver port. Since fiber optic transceivers have different interface types and connect different types of cables, it is not that simple to choose a right loopback for our transceiver. This post will be a guide on how to choose a right loopback cable for specific transceiver module.

Fiber Loopback Types and Configurations

Before deciding which loopback cable to use, we should firstly know the structure and classification of fiber loopback cable. Generally, a fiber loopback is a simplex fiber optic cable terminated with two connectors on each end, forming a loop. Some vendors provide improved structure with a black enclosure to protect the optical cable. This designing is more compact in size and stronger in use. Based on the fiber type used, there is single-mode loopback and multimode loopback, available for different polishing types. According to the optical connector type of the loopback, fiber loopback cables can be divided to LC, SC, FC, ST, MTP/MPO, E2000, etc. In testing fiber optic transceiver modules, the most commonly used are LC, SC and MTP/MPO loopback cables.

lc&sc loopback cable
Figure 1: LC & SC Loopback Cable

The LC and SC loopbacks are made with simplex fiber cable and common connectors; it’s not difficult to understand their configurations. As for the MTP/MPO loopback, it is mainly used for testing parallel optics, such as 40G and 100G transceivers. Its configuration varies since the fiber count is not always the same in different applications.

8 Fibers MTP/MPO Loopback Cable Configuration

In a 8 fibers MTP/MPO loopback, eight fibers are aligned on two sides of the connector, leaving the central four channels empty. And the fibers adopt a straight configuration of 1-12, 2-11, 5-8, 6-7. The polarity channel alignment is illustrated in the following figure.

8 Fibers Loopback Polarity Channel Alignment
Figure 2: 8 Fibers Loopback Polarity Channel Alignment
12 Fibers MTP/MPO Loopback Cable Configuration

The only difference between the 12-fiber MTP loopback and the 8-fiber loopback is that the central four channels are not empty. Its alignment is 1-12, 2-11, 3-10, 4-9, 5-8, 6-7.

12 Fibers Loopback Polarity Channel Alignment
Figure 3: 12 Fibers Loopback Polarity Channel Alignment
24 Fibers MTP/MPO Loopback Cable Configuration

The 24 fibers MTP loopback also adopts type 1 polarity. Its alignment design is shown below.

24 Fibers Loopback Polarity Channel Alignment
Figure 4: 24 Fibers Loopback Polarity Channel Alignment
Which to Choose for a Specific Transceiver?

Considering the common features of the transceiver and the loopback, we should think about the connector type, polish type, and cable type when selecting a loopback for the transceiver. The selection guide for some mostly used transceiver modules is summarized in the following tables.

Table 1: Loopback choices for 10G SFP+ transceivers

Model Interface type Cable Type Suited Loopback

LC/UPC Duplex Multimode Fiber Loopback


LC/UPC Duplex Single-mode Fiber Loopback


Table 2: Loopback choices for 40G QSFP+ transceivers

Model Interface type Cable Type Suited Loopback

8/12 Fibers MTP/UPC Multimode Fiber Loopback


8/12 Fibers MTP/APC Single-mode Fiber Loopback

40GBASE-LR4 LC Duplex (PC) SMF

LC/UPC Duplex Single-mode Fiber Loopback


LC/UPC Duplex Multimode/Single-mode Fiber Loopback

Table 3: Loopback choices for 100G QSFP28 transceivers

Model Interface type Cable Type Suited Loopback

8/12 Fibers MTP/UPC Multimode Fiber Loopback


8/12 Fibers MTP/APC Single-mode Fiber Loopback

100GBASE-LR4 LC Duplex (UPC) SMF

LC/UPC Duplex Single-mode Fiber Loopback

Table 4: Loopback choices for CFP transceivers

Model Interface type Cable Type Suited Loopback

8/12 Fibers MTP/UPC Multimode Fiber Loopback


SC/UPC Duplex Single-mode Fiber Loopback


24 Fibers MTP/UPC Multimode Fiber Loopback


This post discusses specific fiber loopback choices for some most commonly used fiber optic transceivers. For other transceiver modules that are not mentioned in this post, we can also know how to choose a suitable loopback for it by getting details about its interface type, physical contact and cable type.

Importance of Using Fiber Color Codes in Data Center

The utilization of color codes in data center effectively helps technicians make better cable management and reduce human errors. Without redundant checking process, people can easily get the information of the device by only one look. Making good use of the color code system can surely save much time during work. This article will mainly present the widely accepted color code system and its important functions.


Introduction to Color Code Systems

Fibers, tubes and ribbons in fiber optic cables are usually marked with different color codes to facilitate identification. There are many color code systems for national or international use. All these systems are characterized by using 12 different colors to identify fibers that are grouped together in a common bundle such as a tube, ribbon, yarn wrapped bundle or other types of bundle.

Different color code standards may be used in different regions. For example, the S12 standard is used for micro cables and nano cables in Sweden and other countries. The Type E standard is defined by Televerket and Ericsson used in Sweden. The FIN2012 standard is used in Finland, etc. However, there is one color code system widely recognized in the world, namely the TIA/EIA-598 standard.

Specifications of TIA/EIA-598 Color Codes

The following picture gives the fiber color coding of TIA/EIA-598 standard. If more than 12 fibers or tubes are to be separated, the color sequence is normally repeated with ring marks or lines on the colored fibers and tubes. As for the fiber cable jacket, orange, yellow, aqua and black color codes are used for their distinction.


Functions of Fiber Color Codes in Data Center
Distinguishing Fiber Grades

As mentioned above, the outer jacket color codes are able to identify the fiber grades. OM1/OM2 cables often adopts the orange jacket, OM3/OM4 cables with aqua jacket, single-mode cables with yellow jacket and hybrid cables (indoor/outdoor cables and outside plant cables) with black jacket. One thing to note is that the mix of OM1 and OM2 or OM3 and OM4 cables may be troublesome. You should make sure not to mingle these cables with the same color code.

Identifying Fiber Patch Cords

Using color codes to label fiber patch cords can reduce the potential for human error. For instance, you may highlight mission-critical patch cords in red, and then teach all technicians that a red patch cord should only be moved with proper authorization or under supervision. Likewise, keeping the fiber connector color consistent with fiber grade color standards will make it simple for technicians to use the right connectors with the cables.

Separating Different Ports

The color-coded port icons can be helpful in identifying different network routings in accordance with internal needs. By tagging each patch panel port, you can simplify and streamline network management.

Differentiating Connector Boots

You can use color codes on connector boots to make routine maintenance and moves, adds and changes easier by helping technicians preserve correct parallel groupings for switch ports. If you change your connector color, you need to ensure that your fiber cable color represents the fiber grade to avoid confusion. You can also change the color of a connector boot to differentiate between different aspects of the network, making it easy for technicians to view the contrast within a panel.


Visual management is more intuitive for specialists to supervise the data center. Color code system has provided an ideal and easy way to solve the cabling problem. Inside the cables, the fiber buffers are also color-coded with standard colors to make connections and splices easier. Therefore, if you are still bothered by these issues of fiber patch cables, using the color code system is a good way to go.

Things You Need to Know About ADSS Fiber Cables

When it comes to OSP (outside plant) deployment, many types of fiber optic cables are used for different OSP applications. ADSS (all-dielectric self-supporting) cable is the type that is strong enough to support itself between structures without using conductive metal elements. It is often installed along aerial transmission lines to be a communication medium for electrical utility companies. Both single-mode and multimode fibers can be arranged in ADSS cables. And when using single-mode fibers, the cable can carry the maximum of 144 fibers. But do you know the basic structures of ADSS cable? What are the advantages of using ADSS cable? And how can you prevent ADSS cable from damage? This article will give you all the answers.


Structures of ADSS Cable

There are generally two kinds of structures for ADSS cable. One is called as central tube structure. From the following picture, the fiber of a certain length is placed in a PBT loose tube filled with water-blocking material. Then it is wrapped with aramid yarn according to the desired tensile strength and extruded with PE or AT sheath. This structure has a smaller diameter and lighter weight. But the fiber length is limited.


The other type of structure is called as stranded structure. The following picture shows that the fiber loose tubes are surrounding around a central strength member (usually as FRP material). And the rest parts are similar to the central tube structure. This type is able to obtain longer fiber length. Although the diameter and weight is relatively big, it is better to be deployed for large span applications.


Benefits of ADSS Cable

There are many advantages of using ADSS cable. The overall weight and diameter of the cable are small which is a relief to the towers and poles. And its total transmission range is large enough to reach up to 1200 meters. Using the polyethylene sheath will also protect the cable from corrosive effect. ADSS cable’s non-metallic structure makes it possible to be anti-lightning. And the aramid yarn helps the cable to have good tensile performance and temperature performance under extreme weathers. The maximum lifespan of ADSS fiber cables can even reach up to thirty years.

Precautions for ADSS Cable Damage
  • Point 1, since many cables are running through mountainous areas, it is inevitable that the cables will be scratched or bent when come across trees or rocks. Especially for the cable sheath damage, it will greatly harm the service life of cable because the surface can be corroded once exposed to the dust and salty environment. Thus, the cable installation should be under careful examination and monitoring.
  • Point 2, due to the partial force during the line construction, common accidents like broken fiber and high loss point can be occurred. Lots of people think it is the problem of cable quality, but actually it is because of the wrong construction process. Therefore, taking control of the constant tension at a uniform speed during installation is very important.
  • Point 3, another common damage is the broken fiber at strain towers. This is because of the wrong operation or partial force on fibers. During the construction, installers must pay attention to the proper angle and pulling direction of fibers to avoid such accidents.

ADSS fiber cable is ideal for installation in distribution as well as transmission environments. It does not need support or messenger wire, a single pass is sufficient for installation which make it a cost-effective and simple way of setting up fiber optic networks. With careful installation, this type of fiber optic cable can bring much convenience for the proper application.

Applications for Outside Plant Fiber Optic Cables

Inside plant refers to the cabling running inside a building. Similarly, outside plant is the cabling running outdoors. Outside plant cables are thicker because of more durable insulation jackets. As for fiber optic communication, there are many types of outside plant fiber optic cables. Some have extra protections to prevent corrosion and other elemental interference. Outside plant fiber optics are widely used in telephone networks, CATV, metropolitan networks, utilities and so on. If you want to choose the right outside plant fiber optic cable, its applicable environment is an important factor for consideration. This post will introduce some common outside plant fiber optic cables and typical outdoor application environments.

Several Types of Outside Plant Fiber Optic Cables

Outdoor breakout cable is perfect for rugged applications and installations that require increased performance. It is usually made of several bundled simplex cables wrapped in a common cable jacket. The fungus, water and UV protections and temperature durability are beneficial to its outside applications. Its design of individual fiber reinforcement enables the quick termination to connectors and omits the use of patch panels or boxes. With much less termination work, outdoor breakout cable is more cost-effective when small fiber counts and short distances are required.


Outdoor Loose Tube Cable

Outdoor loose tube cable has the gel-filled design protecting the cable from moisture environment. The gel within the loose-tube construction stops the penetration of water and keeps it away from the fiber. Also, it keeps water from freezing near the fiber at low temperatures which reduces the chance of stress fractures. Fibers are bundled inside a small plastic tube that can protect fibers from outside stresses. Outdoor loose tube cable is often used in conduits, strung overhead or buried directly into the ground.


Outdoor Ribbon Cable

Outdoor ribbon cable has high fiber counts and small cable diameter. It contains the most fibers in the smallest cable. These fibers are laid out in rows as ribbons, and ribbons are laid on top of each other. Likewise, it also has gel-filled protection to block outside water. Ribbon cable makes installation much faster and easier since mass fusion splicers can join a ribbon at once.


Outdoor armored cable is a direct buried type that prevents itself from animal bite. The metal armoring between two jackets effectively prohibits rodent penetration. Outdoor armored cable can be divided into light armored and heavy armored types. The former has the protective plastic jacket with the same durability and longevity of a stainless steel cable with a lighter weight. The latter is wrapped in a wire circle to be applied for underwater regions that near shores and shoals.


Outside Cable Plant Applications

Outside cable plant deployment can be implemented in many environments. Above-ground, underground, buried and underwater are the typical applications.

Above-ground Cable Plant

Above-ground cable plant can be exposed to extreme temperatures, and to humidity that varies with the seasons and with daily temperature changes. Cables under such circumstances should be durable to adapt to extreme weathers and water penetration.

Underground Cable Plant

Underground cable plant usually applies cables in underground structures including the utility holes, controlled environmental vaults, ducts and so on. The condition in utility holes and ducts sometimes can be corrosive because of man-made chemicals. Cables with corrosion-proof materials are perfect for this environment.

Buried Cable Plant

Buried cable plant applies cables directly into the soil. Cables can also be exposed to the same corrosive environment as underground plant. But animal bite is an additional problem. Cables for this application should be very tough to endure both chemical corrosion and animal attack.

Underwater Cable Plant

Underwater cable plant are located beneath the surface of water. The water can range from relatively pure to brackish, or to badly contaminated with industrial effluent. Cables for underwater plant are extremely rugged, with fibers in the middle of the cable inside stainless steel tubes and the outside coated with many layers of steel strength members and conductors for powering repeaters.


Unlike indoor cables, outside plant fiber optic cables must be wrapped in different layers to withstand the severe installation conditions. Choosing the right kind of outdoor cable can save you a great deal for long-term maintenance. And your project application is an important aspect that will affect the selection of fiber optic cables.