Can I Use QSFP+ Optics on the 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 modules. 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.

Conclusion

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.

Original source : http://www.chinacablesbuy.com/can-use-qsfp-optics-qsfp28-port.html

100G QSFP28 PSM4 to Address 500m Links in Data Center

100G QSFP28 PSM4 optics is a type of 100G optical transceiver that provides a low-cost solution to long-reach data center optical interconnects. 100G PSM4 (parallel single-mode 4 lane) standard is mainly targeted to data centers that based on a parallel single-mode infrastructure for a link length of 500 m. Compared with the hot-selling 100GBASE-SR4 and 100GBASE-LR4 optics, 100G QSFP28 PSM4 recently wins the popularity among the overall users. This article will provide a complete specification of the 100G QSFP28 PSM4 transceiver and explain the reason why people would need QSFP28 PSM4.

QSFP28 module

QSFP28 PSM4—A Low-Cost but Long-Reach Solution

100G QSFP28 PSM4 is compliant with 100G PSM4 MSA standard, which defines a point-to-point 100 Gb/s link over eight parallel single-mode fibers (4 transmit and 4 receive) up to at least 500 m. PSM4 uses four identical lanes per direction. Each lane carries a 25G optical transmission. The 100G PSM4 standard is now available in QSFP28 and CFP4 form factor. Table 2 shows the diagram of the 100G QSFP28 PSM4 Specification. 100G PSM4 is a low-cost solution. Its cost structure is driven by the cost of the fiber and the high component count. FS.COM offers the Cisco compatible 100G QSFP28 PSM4 at US$750.00.

diagram of QSFP28 PSM4

As you can see in the above image, 100G QSFP28 PSM4 transceiver uses four parallel fibers (lanes) operating in each direction, with transmission distance up to 500 meters. The source of the QSFP28 PSM4 module is a single uncooled distributed feedback (DFB) laser operating at 1310 nm. It needs either a directly modulated DFB laser (DML) or an external modulator for each fiber. The 100GBASE-PSM4 transceiver usually needs the single-mode ribbon cable with an MTP/MPO connector.

Why Do We Need 100G QSFP28 PSM4?

100G PSM4 is the 100G standard that has been launched by multi-source agreement (MSA) to enable 500m links in data center optical interconnects. But as we all know, there are several popular 100G interfaces out there on the market, such as QSFP28 100GBASE-SR4, QSFP28 100GBASE-LR4, QSFP28 100GBASE-CWDM4, and CFP 100GBASE-LR4, etc. So with so many options, why do we still need 100G QSFP28 PSM4?

To better help you make up your mind, you need to figure out the following questions:

Q1: What are the net link budget differences between PSM4, SR4, LR4 and CWDM?
Table 3 displays the detailed information about these 100G standards.

100GBASE-PSM4 100GBASE-CWDM4 100GBASE-SR4 100GBASE-LR4
4-wavelength CWDM multiplexer and demultiplexer No need Need No need Need
Connector MPO/MTP connector Two LC connectors MPO/MTP connector Two LC connectors
Reach 500 m 2 km 100 m 10 km

Note: the above diagram excludes the actual loss of each link (it is the ideal situation). In fact, WDM solution are at least 7 db worse link budget than PSM4. For a 2 km connectivity, a CWDM module will have to overcome about 10 db additional losses compared to PSM4. And the 100G LR4 optics at 10 km is 12 db higher total loss than PSM4.

Q2: What power targets are achievable for each, and by extension what form factors?
According to the IEEE data sheet, the WDM solutions cannot reasonably fit inside QSFP thermal envelop, while PSM4 can fit inside the QSFP thermal envelope. That means you would need the extra power for the WDM solution of your network. But if you use the QSFP PSM4, this won’t be a problem.

All in all, a 100G QSFP28 PSM4 transceiver with 500m max reach is a optional choice for customers. Because other 100G optics are either too short for practical application in data center or too long and costly. QSFP28 PSM4 modules are much less expensive than the 10 km, 100GBASE-LR4 module, and support longer distance than 100GBASE-SR4 QSFP28.

Summary

QSFP28 PSM4 is the lowest cost solution at under one forth the cost of either WDM alternatives. 100G QSFP28 PSM4 can support a link length of 500 m, which is sufficient for data center interconnect applications. 100G QSFP28 PSM4 also offers the simplest architecture, the most streamlined data path, higher reliability, an easy upgrade path to 100G Ethernet.

Compatible Test of Cisco QSFP-40G-SR4 Optics

When purchasing the third party optics, customers usually suffer from the poor quality and compatibility issue, which is the major obstacle of OEM market. Just as a saying goes, what is good is not cheap. However, this article will prove that the cost-effective OEM optics from FS.COM are well worth the penny.

FS.COM, as a professional and reliable manufacturer and supplier of compatible optical transceiver, provides a series of self-developed products which can be highly compatible with many major brands, such as Cisco, HPE, Juniper, Brocade, Arista, etc. In this blog, we are going to present a compatibility testing of our hot-selling Cisco compatible QSFP-40G-SR4 optics on Cisco Nexus 9396PX.

Cisco QSFP-40G-SR4 Optics

Before we come to the major part, let’s have a brief overview of the 40G QSFP-40G-SR4 and the Cisco Nexus 9396PX switch. Cisco QSFP-40G-SR4 Compatible 40GBASE-SR4 QSFP+ transceiver is a short-range transceiver for 40 Gigabit Ethernet. It supports link lengths of 100m and 150m on laser-optimized OM3 and OM4 multimode fiber, respectively. Cisco QSFP-40G-SR4 enables high bandwidth 40G optical links over 12-fiber parallel fiber terminated with MPO/MTP multifiber connectors, which is also optimized to guarantee interoperability with any IEEE 40GBase-SR4 and 10GBase-SR.

Our Cisco compatible QSFP-40G-SR4 optics is fully tested with most Cisco platforms to ensure compatibility and compliance. Thus, it can be supported on a wide range of Cisco equipment, such as Cisco ASR 9000 series, Nexus 9000 series, Nexus 6000 series, and so on.

Cisco Nexus 9396PX Switch

Cisco Nexus 9396PX belongs to the Cisco Nexus 9000 series. It delivers a comprehensive line-rate layer 2 and layer 3 featuring in a two-rack-unit form factor. It can support 1/10/40 Gbps of switching capacity with forty-eight 1/10 Gigabit Ethernet SFP+ port and twelve 40 GE QSFP+ nonblocking ports. The main advantage of this switch is that you can reuse the existing 10 Gigabit Ethernet multimode cabling for 40 Gigabit Ethernet by connecting the 40Gb bidirectional transceiver. Figure 1 shows the Cisco Nexus 9396PX switch.

cisco-nexus-9396px-ports-information

The Testing Procedure of the Cisco QSFP-40G-SR4 on Cisco Nexus 9396PX Switch

In FS.COM’s test center, we care of every detail from staff to facilities to ensure our customers to receive the optics with superior quality. Just take our hot-selling Cisco QSFP-40G-SR4 optics as an example, the procedure can be quite simple that can be concluded in three steps:

1. Plug the Cisco QSFP-40G-SR4 compatible QSFP+ into the 40-Gbps ports of the Nexus 9396PX

2. Plug the cleaned MTP patch cord into the optical ports of the transceivers

3. View the state of LED light and more information in the CLI.

Besides the above procedures, we also have a testing demo of QSFP-40G-SR4 Cisco compatible module testing on Nexus 9396PX.

Conclusion

At the end of the article, you must know the reason why FS.COM is the number one choice of compatible optical transceivers. Not only the Cisco QSFP-40G-SR4 optics, but other reliable compatible fiber optic transceivers from FS.COM are the best-seller products over the past years. If you are the major brand user like Cisco, HPE or Juniper, and want to cut down your budget this time, you might want to have a look at our cost-effective compatible fiber optic transceiver.

Introduction to Horizontal and Vertical Cable Manager

For many IT manager or data center professionals, one of the most difficult task is to keep cables in proper order. Image that you walk into a sever room to troubleshoot cables because of the bad cable management, you see the cable here, cable there, cable everywhere. Can you walking through this without crying?

bad cable management

Now that you have looked at the horrible cable management, it is time for you to do something to avoid joining the terrible cable management hall.

From the above image, we can see that there are bunches of cables in one sever room, which includes power cables, network cables, and in some cases, keyboard or mouse cables. In this situation, proper rack cable management is absolutely essential. Without it, you will need to trace out every cable in the rack anytime, this, of course, can be very time consuming and difficult.

Fortunately, there are many excellent products available on the market, such as cable manager, wire duct, patch panel, cable ties and so on, which can help make cable management in rack environments much faster, easier and more effective. Whether you handle running cables for a massive corporate data center or for a small business, learning more about cable management can be very helpful. This article will have a brief introduction to the vertical and horizontal cable managers.

Vertical & Horizontal Cable Manager

Good cable management is essential. When installing cables in a sever rack, you will undoubtedly have to run them both vertically and horizontally. The best solution for this cabling is to run all the cables horizontally from the sever directly to the vertical cable management rack. In this case, you would need the cable managers to hold the cables smugly and safely. This vertical and horizontal cable manager provides plenty of room for all the cables.

Vertical cable manager just as seen in the below image, utilizes the additional space to manage the slack from patch cords, and make sure that they can easily route the largest cable diameter in your plan. For static environments, you can consider installing another vertical cable manager behind the racks, which does not block access to components in the space between the racks. Vertical racks can be also installed under a desk or against a wall and accommodate networking equipment up to 4 RU.

vertical cable manager

Horizontal cable managers allow neat and proper routing of the patch cables from equipment in racks and protect cables from damage. If you are using flat-faced patch panels or network switches that cable from above or below, horizontal cable manager will complete the support pathway for patch cords between the cabling section and the exact connection point (port) on the patch panel or switch. Alternately, horizontal management can be used to create rack-to-rack pathways for patch cords. The following image shows the 2u horizontal cable manager panel.

horizontal cable manager panel

Select a style of horizontal cable management that complements the cabling section (vertical manager). Generally, it is good practice to plan 1U of horizontal cable management for every 2U of connectivity. Cable fill should equal at minimum, half of the ports supported by the cable manager. This method assumes that patch cords enter from both sides of the rack. Capacity should equal port density when cables enter from one side of the rack only.

In some case, vertical cable manager and horizontal cable manager are often used together. The vertical cable manager guides cables to the floor and horizontal cable management draws away from equipment.

FS.COM Cable Manager

FS.COM cable management provides an engineered solution for managing high-density cabling applications, delivering increased performance to match the demands of data center applications. Use FS.COM Vertical and Horizontal Cable Managers on the sides of racks to manage premise cables, patch cords and jumper cords.

Features include:

  • Four styles: Finger duct, D-rings, Brushed, Telephone Line
  • Structure: Single-sided, Double-sided
  • Available in a variety of heights, depths and widths (rack up to 45 U)
  • Material: plastic, metal, semimetal
  • Vertical manager door opens to right or left with single knob; horizontal manager has snap-on cover
  • Rigid vertical manager trough minimizes movement when installed on the end of a row or racks; full rectangular base supports heavy cable bundles
  • Vertical cable managers feature panels that support various optional cable management accessories to divide the interior space and manage cable slack
  • The panel on dual-sided vertical managers are movable and allow for flexibility in the volume of cable management space
  • Wide variety of accessories include cable ties, cable management rings, cable lacing bars, J-hook and wire loom.

Conclusion

If you have picked the right rack cable manager (whether the vertical cable manager or the horizontal cable manager), the next important thing you should do is make sure you make a good preparation before deploying. Plan out every detail of the installation will help to ensure the cable management activities perform as quickly and easily as possible.

An Eye on the Copper Patch Panels

Are you tired of messy network? As the world embraces the increasingly faster data-rate network, IT managers felt great stress over the inability to organize and create a neat rack mounted environment. Patch panels allows the easy management of patch cables and link the cabling distribution areas, which paves the way for a refreshing new approach to a neat optical network.

Patch panels are usually installed on enclosures or racks to provide an easy way to organize connections. Patch panels are available in many different variations. Key design variations include:

  • Jack module type
  • Patch panel material type
  • Unshielded patch panels vs. shielded patch panels
  • Flat patch panels vs. angled patch panels
  • Standard patch panels vs. high-density patch panels
  • Port labeling

Patch panels also allow several cable connectors to be used (LC for fiber and RJ45 for copper). Today’s article will be concentrated on the illustration of the copper patch panels, especially cat5e patch panels and cat6 patch panels.

Copper Patch Panels

The cat5e and cat6 shielded and unshielded patch panels are the commonly used copper patch panels on the market that are suitable for communication socket interconnection between equipment room, working area and crossover terminal connection. This patch panels use the copper patch cord to contains ports to connect and manage incoming and outgoing Ethernet cables. Besides the shielded and unshielded patch panels, copper patch panels include flat and angled types from appearance design.

Flat patch panels help horizontal cable managers to organize and route cables into vertical managers. Angled patch panels are easy for cable termination and can improve patch cord routing. They serve as alternatives for management that need no rack space for horizontal management. The angled design increases rack density, managing high-density applications in one-fourth the area needed for conventional cable management systems. But angled panels are not good for cabinet installation due to the front depth requirements.

angled patch panel

Figure 1 shows the angled patch panels that allow cables to be mounted directly into the vertical cable manager. Angled patch panels do not need the additional cable manager to be installed above and below the patch panels, which makes them perfect for high-density areas. Next part will go on to talk about the cat5e and cat6 patch panels individually and specifically.

Cat5e Patch Panels

Cat5e patch panels allows fast and easy installation and cable management to copper Gigabit switches. It is compliant with TIA/EIA 568 industry specifications and features both T-568A and T-568B wiring configurations. Cat5e patch panels are ideal for Ethernet network applications. Figure 2 displays the 24 Ports Cat5e Feed-Through Patch Panel, UTP Unshielded, 1U Rack Mount.

cat5e patch panel

This type of patch panel mount the patch panel using four rack screws. With the module design, feed-through module can easily achieve high density access. No punch down is required as well. Last but not the least, UTP network cable inserts directly, simple operation, to achieve seamless integration between cables.

Cat6 Patch Panels

Cat6 patch panels deliver a steady 250 MHz connection to copper Gigabit switches. Ideal for Ethernet, Fast Ethernet and Copper Gigabit Ethernet (1000Base-T) network applications. Backward compatible with Cat. 3, 4, 5, and 5e cabling. Cat6 patch panels also meet the TIA/EIA 568 industry specification. Each patch panel terminates with standard 110 termination tools on the rear, which allows quick installations. Cat6 patch panels are available in 6-port and 8-port module groupings, in 8, 12, 24, and 48-port sizes.

Conclusion

This article provided some detailed information about copper patch panels. When selecting between the cat5e and cat6 patch panels, you should consider the density supported (24 ports or 48 ports), shielded or unshielded and the compatibility with your racks. FS.COM provides the cost-effective cat5e and cat6 patch panels in 24 ports, 48 ports per 1U or 2U panel. If you have any interest, please contact us directly.

Comparison Between Different Fiber Optic Cable Types

Nowadays more and more fiber-based networks have been built in the backbone and risers environment. Both multimode and single-mode fibers are available for the applications. But different fiber types have briefly different limitations for speed and maximum distance. These characteristics they possess and the way cause the fiber to operate determine the application to which a given fiber is most appropriate. Today’s article will offer you some information about the classification of fiber optic cables and the difference in speed and distances.

Difference Between OM Multimode Fibers

Multimode fibers, according to the specification and briefly by their bandwidth performance are commonly classified into OM1, OM2, OM3 and OM4. Each multimode type has different transmission data rates, link length and bandwidth for specific protocols, applications and transceiver types. Table 1 outlines the international standards organization classification for multimode fiber which describe the strength for speed and distance.

multimode-fiber

From the above table, we can see that OM1 is the 62.5-micron fiber, while OM2/OM3/OM4 are the 50-micron multimode fibers. OM1 multimode fiber was used to be the most common multimode fibers in the 80’s and 90’s. However, it is generated accepted that OM1 will soon be obsolete for the lowest data carrying capacity and shortest distance limitations as compared with other multimode fibers. As for the 50-micron multimode fibers, they are the most commonly used fiber types today, especially the OM3 and OM4 cables. Why do the multimode fibers with a smaller diameter have better performance than the large one? Please read on.

In terms of the performance in 50-micron and 62.5-micron multimode fibers, the difference lies in the fibers’ bandwidth, or the signal-carrying capacity. Bandwidth is actually specified as a bandwidth-distance product with units of MHz-km that depends on the data rate. As the data rate goes up (MHz), the distance that rate can be transmitted (km) goes down. Thus, a higher fiber bandwidth can enable you to transmit at higher data rates or for longer distances. For example, 50-micron multimode fiber offers nearly three times more bandwidth (500 MHz-km) than FDDI-grade 62.5-micron fiber (160 MHz-km) at 850 nm.

While fiber bandwidth is a critical factor in determining link length and data rate, transmitter and receiver characteristics also matters. For 850-nm Gigabit Ethernet, these bandwidth values support link lengths of 220 meters over 62.5-micron fiber and 550 meters over 50-micron fiber. For example, Cisco GLC-SX-MM operating at 850-nm can support a link distance of 550 m over 50-micron fiber (OM2). Today, the 850-nm operating window is increasingly important, as low-cost 850-nm lasers such as verti cal-cavity surface-emitting lasers (VCSELs) are becoming widely available for network applications. VCSELs offer users the ability to extend data rates at a lower cost than long-wavelength lasers. Since 50-micron multimode fiber has higher bandwidth in the 850-nm window, it can support longer distances using these lower-cost VCSELs. Thus, 50-micron multimode fiber is more suitable for fiber backbones running Gigabit Ethernet and higher-speed protocols over longer distances.

Multimode vs. Single-mode Fibers

Single-mode fiber, owing to the more expensive electronics required in the network, is usually used for much greater-reach applications but not a cost-effective investment for future application in building. As the multimode fibers can be divided into OM1, OM2, OM3 and OM4 fiber types, single-mode fibers usually come in OS1 and OS2 fibers. For the detailed information, please look at the article “The Truth About OS1 and OS2 Optical Fiber”.

Jacket color is sometimes a simple method to distinguish multimode cables from single-mode ones. The standard TIA-598C recommends, for non-military applications, the use of a yellow jacket for single-mode fiber, and orange or aqua for multimode fiber, depending on type as you can seen in the Figure 2.

fiber-optic-cable

Besides the jacket color, the difference between multimode and single-mode optical fiber (9-mircon core) is that the former has much larger core diameter; much larger than the wavelength of the light carried in it. Because of the large core and the possibility of large numerical aperture, multimode fiber has higher “light-gathering” capacity than single-mode fiber. In practical terms, the larger core size simplifies connections and also allows the use of lower-cost electronics such as light-emitting diodes (LEDs) and vertical-cavity surface-emitting lasers (VCSELs) which operate at the 850 nm and 1300 nm wavelength (single-mode fibers used in telecommunications typically operate at 1310 or 1550 nm). However, compared to single-mode fibers, the bandwidth & distance product limit of multimode fiber is lower. Because multimode fiber has a larger core-size than single-mode fiber, it supports more than one propagation mode; hence it is limited by modal dispersion, while single mode is not.

fiber-cable-type

The light sources used in these two cable types also plays a critical role in the performances. The LED light source sometimes used with multimode fiber produce a range of wavelengths and these each propagate at different speeds. This chromatic dispersion is another limit to the useful length for multimode fiber optic cable. In contrast, the lasers used to drive single-mode fibers produce coherent light of a single wavelength. Due to the modal dispersion, multimode fiber has higher pulse spreading rates than single mode fiber, limiting multimode fiber’s information transmission capacity. Thus, single-mode fibers are often used in high-precision scientific research because restricting the light to only one propagation mode allows it to be focused to an intense, diffraction-limited spot.

Conclusion

The growth in subscribers’ demand for more sophisticated electronics and web-connected services increases the requirement for information storage and cloud technology. End-users also want to know how to choose the right cable type for your network application. Therefore , I hope after reading this article you might have learned something from it.

The Do’s & Don’ts of UTP Cable Installation

With the technology evolving rapidly and new products keep coming out, optical technicians have to upgrade their knowledge accordingly. Take the UTP (unshieled twisted pair) network cabling as an example, lately telecommunication industry witnessed the evolution of copper cable from the old cat 3, cat 5 to the existing popular cat 5e and cat 6 cable (even to the cat 7 cable or cat8). Therefore, cable installers attach great importance on the TIA-568B installation. Even the experienced installer may discover the problems that they have never been aware of before. Today’s article is going to present all the detailed information necessary to complete a fully compliant TIA-568B UTP installation.

Overview of UTP Cable & TIA-568B Wiring Standard

Designed primarily for data transmission in local area networks (LANs), UTP network cable is a 4-pair, 100-ohm cable that consists of 4 unshielded twisted pairs surrounded by an outer jacket. Each pair is wound together for the purposes of canceling out noise that can interfere with the signal. So, remember to keep UTP cables as far away from potential sources of EMI (electrical cables, transformers, light fixtures, etc.) as possible. UTP cables should maintain a 12-inch separation from power cables.

In terms of the TIA-568B wiring scheme, this standard was published in 2001 to replace the 568A standard, which is now obsolete. The original purpose of the EIA/TIA 568 standard was to create a multiproduct, multivendor, standard for interoperable connectivity. The 568B standard sets minimum requirements for the various categories of cabling.

t568-wiring-scheme

Figure 1 shows the wiring diagrams imprinted on the jacks. The upper diagram is 568A, and the lower diagram is 568B. We can clearly see the only difference between 568A and 568B is that pairs 2 and 3 (orange and green) are swapped. For detailed information about 568A and 568B, please read the previous article “How to Configure the RJ45 Pinout”.

Do’s and Don’ts of UTP Installation

Before you proceed the following article, you must understand that this article is for general information only. Always check with the local store or cabling consultants when planning a network cabling installation.

Things You Should Do

For the UTP cable, or all the copper cables, you take the following instructions seriously during the installation.

  • Run all cables in a Star Configuration so that all network links are distributed from, or home run to, one central hub. Visualize a wagon wheel where all of the spokes start from on central point, known as the hub of the wheel.
  • The UTP cable run must be kept to a maximum of 295 feet, so that with patch cords, the entire channel is no more than 328 feet.
  • Maintain the twists of the pairs as close as possible to the point of termination, or no more than 0.5″(one half inch) untwisted.
  • Make only gradual bends in the cable where necessary to maintain the minimum bend radius of 4 times the cable diameter or approximately 1″ radius (about the roundness of a half-dollar).
  • Dress the cables neatly with Velcro cable ties (see in the below image), using low to moderate pressure.

    cable-ties

  • Use low to moderate force when pulling cable. The standard calls for a maximum of 25 lbf (pounds of force). Install proper cable supports, spaced no more than 5 feet apart.
  • Use cable pulling lubricant for cable runs that may otherwise require great force to install. (You will be amazed at what a difference the cable lubricant will make)
  • Always label every termination point at both ends. Use a unique number for each network link. This will make moves, adds, changes, and troubleshooting as simple as possible.
  • Always test every installed segment with a cable tester to make sure the attenuation under control.
  • Always install jacks in a way to prevent dust and other contaminants from settling on the contacts. The contacts (pins) of the jack should face up on flush mounted plates, or left, right, or down (never up) on surface mount boxes.
  • Always leave extra slack neatly coiled up in the ceiling or nearest concealed place. It is recommended that you leave at least 5 feet of slack at the work outlet end, and 10 feet of slack at the patch panel end.
  • Always use grommets to protect cable when passing through metal studs or anything that can possibly cause damage.
  • Choose either 568A or 568B wiring scheme before you begin your project. Wire all jacks and patch panels for the same wiring scheme (A or B).
  • Always obey all local and national fire and building codes. Be sure to firestop all cables that penetrate a firewall. Use plenum rated cable where it is mandated.

Things You Can Not Do

You should never proceed the following steps, or you will end up with permanent damage to the geometry of the cable.

  • Skin off more than 1″ of jacket when terminating UTP cable.
  • Allow the cable to be sharply bent, twisted, or kinked at any time.
  • Over tighten cable ties or use plastic ties.
  • Splice or bridge UTP cable at any point. There should never be multiple appearances of cable.
  • Use excessive force when pulling cable.
  • Use oil or any other lubricant not specifically designed for UTP network cable pulling as they can infiltrate the cable jacket, causing damage to the insulation.
  • Tie cables to electrical conduits, or lay cables on electrical fixtures.
  • Install cable that is supported by the ceiling tiles. This is unsafe, and is a violation of the building codes.
  • Never install cables taught. A good installation should have the cables loose, but never sagging.
  • Mix 568A and 568B wiring on the same installation.

In Closing

It is rare that we can directly use the patch cables or short link copper cable to connect the devices to the switch. In most cases, we need to install cable links to remote locations from patch panels to switch ports, which is far more complex. Therefore, anyone who install UTP cabling should take the dos and don’ts seriously. Any minor mistake can easily become a nightmare in the future.