Net 2
Cable Certifier
A cable certifier is a multi-function tool that verifies that a cable or an installation meets the requirements for a specific architecture implementation. For example, you would use a certifier to verify that a specific drop cable meets the specifications for 1000BaseT networking. · A certifier is very important for Cat 6 cable used with bandwidths at or above 1000 Mbps. Slight errors in connectors or wires can cause the network to function at 100 Mbps instead of the desired 1000 Mbps or 10 Gbps. · Certifiers can also validate the bandwidth capabilities of network interface cards and switches. Many can detect the duplex settings of network devices. · Most certifiers include features of a toner probe, TDR, and cable tester. Certifiers are very expensive and are typically used by organizations that specialize in wiring installations.
Multimeter
A multimeter is a device used to test various electrical properties. A multimeter can measure several parameters: · AC and DC voltage · Current (amps) · Resistance (ohms) · Capacitance Frequency
T568B
Wire color guidelines specified under the EIA/TIA568B standard
10-Megabit, 100-Megabit, Gigabit, and 10-Gigabit Ethernet Cabling Differences
-For 10BASE-T (10-Mbps Ethernet over twisted pair) and 100BASE-TX (100-Mbps Ethernet over twisted pair), only two of the twisted pairs of wires in a Cat 3, Cat 5, or Cat 5e cable are used -1000BASE-T or Gigabit Ethernet uses all four pairs of wires in Cat 5e or above cables. - If Cat 7 cabling is used for 10 Gigabit Ethernet, the cables are terminated with GG45 or TERA connectors.
Coaxial cable grades include:
= RG-58 10Base2 Ethernet networking (also called thinnet) 50 ohms = RG-59 Cable TV and cable networking 75 ohms = RG-6 Cable TV, satellite TV, and cable networking 75 ohms When using coaxial cables, it is important to use cables with the same resistance (impedance) rating.
110 block
A 110 block is a punch down block used to connect individual wires together. · The 110 block comes in various sizes for connecting pairs of wires (for example 50, 100, or 300 pair). · The 110 block has rows of plastic slots. Each plastic slot connects two wires together. oPlace the first wire into the plastic slot on the 110 block. oInsert a connecting block over the wire and slot. The connecting block has metal connectors that pierce the plastic cable sheath. oPlace the second wire into the slot on the connecting block. · C4 connectors connect four pairs of wires; C5 connectors connect five pairs of wires. · When connecting data wires on a 110 block, you typically connect wires in the following order: oWhite wire with a blue stripe followed by the solid blue wire. oWhite wire with an orange stripe followed by the solid orange wire. oWhite wire with a green stripe followed by the solid green wire. oWhite wire with a brown stripe followed by the solid brown wire. 110 blocks are used primarily for telephone applications. They are preferable over 66 blocks in high-speed networks because the introduce less crosstalk. When used for data applications: · Be sure to purchase 110 blocks that are certified for Cat 5, Cat 6 and Cat 6a. When inserting wires, preserve the twist as much as possible.
66 block
A 66 block is a punch down block used to connect individual copper wires together. · The 66 block has 25 rows of four metal pins. Pushing a wire into a pin pierces the plastic sheath on the wire, making contact with the metal pin. · There are two different 66 block configurations: oIn the 25-pair block (also called a non-split block), all four pins are bonded (electrically connected). Use the 25-pair block to connect a single wire with up to three other wires. oWith the 50-pair block (also called a split block), each set of two pins in a row are bonded. Use the 50-pair block to connect a single wire to one other wire. · With a 50-pair block, use a bridge clip to connect the left two pins to the right two pins. Adding or removing the bridge clip is an easy way to connect wires within the row for easy testing purposes. 66 blocks are used primarily for telephone applications. When used for data applications: · Be sure to purchase 66 blocks rated for Cat5. When inserting wires in the block, place both wires in a pair through the same slot to preserve the twist as much as possible.
Bad Connector
A bad connector is a damaged connector that is causing connectivity issues. For example, a broken locking tab on an RJ45 connector can cause intermittent connection problems. Another common connector is when there is a bent or damaged pin, especially on female RJ45 connections and the center wire of a coaxial cable.
Cable Tester
A cable tester (or line tester) verifies that the cable can carry a signal from one end to the other and that all wires are in the correct positions. · High-end cable testers can check for various miswire conditions (wire mapping, reversals, split pairs, shorts, or open circuits). · You can use a cable tester to quickly tell the difference between a crossover and a straight-through cable.. · Most testers have a single unit that tests both ends of the cable at once. Many testers come with a second unit that can be plugged into one end of a long cable run to test the entire cable.
Loopback Plug
A loopback plug, or loopback adapter, reflects a signal from the transmit port on a device to the receive port on the same device. Use the loopback plug to verify that a device can both send and receive signals. · There are loopback plugs for both copper and fiber connections. · A failure in the loopback test indicates a faulty network card. · A successful loopback test means the problem is in the network cabling or another connectivity device. You can purchase pre-made loopback plugs, or you can make an inexpensive one by cutting the end off a cable and manually connecting the transmit wires to the receive wires (connect the wire from pin 1 to the wire at pin 3, and the wire at pin 2 to the wire at pin 6).
Mis-wired Cable
A miswired cable is caused by incorrect wire positions on both connectors. Several wiring problems might exist: · A reverse connection is when a cable is wired using one standard on one end and another standard on the other end, creating a crossover cable. While this condition might be intentional, it can cause problems when a crossover cable is used instead of a straight-through cable. This will reverse the transmit and receive match up; the transmit pins on one end maps to the transmit pins on the other end when they should map to the receive pins on the other end. · Wiremapping is matching a wire with a pin on one end with the same pin on the other end. For example, an error in the wiremapping results when the wire at pin 1 connects to pin 4. · A split pair condition is when a single wire in two different pairs is reversed at both ends. For example, if instead of the solid green wire, the solid brown wire is matched with the green/white wire in pins 1 and 2. With a split pair configuration, the cable might still work (especially if it is short), but it could introduce crosstalk. oWhen the T568A/B standards for making drop cables are followed, one pair is split to meet the standards. In this case, a common split pair error is simply placing all wire pairs in order in the connector instead of splitting the pair according to the standard. When cables are connected using a punch down block, pairs are not split.
Smartjack
A smartjack is an intelligent loopback device installed at the demarcation point for a WAN service. Technicians at the central office can send diagnostic commands to the smartjack to test connectivity and performance between the central office and the demarc. When you contact a WAN service provider for assistance, they might execute a test using the smartjack. A successful test indicates that the problem is within your customer premises equipment (CPE).
Speed Test Website
A speed test website is an online tool that is used to test the bandwidth of your internet connection. There are countless speed test websites available, all of which provide essentially the same information: · Connection latency (ping) · Download speed Upload speed
Time-Domain Reflectometer (TDR)
A time-domain reflectometer is a special device that sends electrical pulses on a wire in order to discover information about the cable. The TDR measures impedance discontinuities (the echo received on the same wire in response to a signal on the wire). The results of this test can be used to identify several variables: · Estimated wire length · Cable impedance · The location of splices and connectors on the wire The location of shorts and open circuits
Toner Probe
A toner probe is composed of two devices that are used together to trace the end of a wire from a known endpoint to the termination point in the wiring closet. To use a toner probe: · Connect the tone generator to one end of the wire. It will send a signal on the wire. In the wiring closet, touch the probe to wires or place the probe close to wires. A sound at the probe indicates that the generated tone has been detected and the wire that you are touching is the termination point for the wire you are tracing.
Intermediate Distribution Frames (IDFs)
A traditional intermediate distribution frame (IDF) is a smaller wiring distribution frame or rack within a building. Like an MDF, the room that houses the IDF along with networking patch panels and rack-mounted equipment is called an IDF. · IDFs are typically located on each floor directly above the MDF, although additional IDFs can be added on each floor as necessary. · IDFs located above the MDF are connected using a vertical cross connect (VCC), or wire bundles that run vertically between the MDF and an IDF. · If a floor has more than one IDF, the IDFs are connected with a horizontal cross connect (HCC).
Voltage Event Recorder
A voltage event recorder keeps track of voltage conditions on a power line. Basic recorders simply keep track of the occurrence of undervoltage or overvoltage conditions, while more advanced devices track conditions over time and create a graph, saving data from a program running on a computer. Some UPS systems include a simple voltage event recorder. Use a voltage event recorder to identify periods of low or high voltage that can adversely affect network components.
Short
An electrical short occurs when electrical signals take a path other than the intended path. In the case of twisted pair wiring, a short means that a signal sent on one wire arrives on a different wire. Shorts occur when two wires touch; this can be caused by worn wire jackets, crushed wires, or a metal object piercing two or more wires.
Environmental Monitor
An environmental monitor does what its name implies—it monitors the environmental conditions of a specific area or device. · Monitors are often used to track the conditions within server rooms (such as temperature, humidity, water, smoke, motion, and air flow). · Typically computers, especially servers, have an internal monitor that measures fan speed and CPU temperature. Many monitors will sound an alarm if a specified temperature or other environmental condition is reached.
Incorrect Termination
An incorrect termination occurs when an incompatible or incorrect connector is used. This can result in reduced performance or complete connection loss.
Open Circuit
An open circuit is when a cut in the wire prevents the original signal from reaching the end of the wire. An open circuit is different from a short in that the signal stops (electricity cannot flow because the path is disconnected).
Optical Time-Domain Reflectometer (OTDR)
An optical time-domain reflector performs the same function as a TDR, but is used for fiber optic cables. An OTDR sends light pulses into the fiber cable and measures the light that is scattered or reflected back to the device. The information is then used to identify specifics about the cable: · The location of a break · Estimated cable length Signal attenuation (loss) over the length of the cable
Attenuation
Attenuation is the loss of signal strength from one end of a cable to the other. This is also known as dB loss. · The longer the cable, the more attenuation. For this reason, it is important never to exceed the maximum cable length defined by the networking architecture. · Cables at a higher temperature experience more attenuation than cables at a lower temperature. A repeater regenerates the signal and removes the effects of attenuation.
Cat 5
Cat 5 supports 100-megabit Ethernet (100BASE-TX) and ATM networking. Cat 5 specifications also support gigabit (1000 Mb) Ethernet.
Cat 5e
Cat 5e is similar to Cat 5 but provides better EMI protection. It supports 100-megabit (100BASE-T) and gigabit (1000BASE-T) Ethernet.
Cat 6
Cat 6 supports 10-Gbps Ethernet (10GBASE-T) and high-bandwidth broadband communications. In most cases, Cat 6 cables include a solid plastic core that keeps the twisted pairs separate and prevents the cable from being bent too tightly.
Cat 6a
Cat 6a is designed to provide better protection against EMI and crosstalk than Cat 6 cabling. Cat 6a provides better performance than Cat 6, especially when used with 10-Gbps Ethernet (10GBASE-T).
coaxial cable
Coaxial cable is a relatively old technology that is usually implemented with a bus topology. It is not suitable for ring or star topologies because the ends of the cable must be terminated.
Crosstalk
Crosstalk is interference that is caused by signals within the twisted pairs of wires (for example, current flow on one twisted pair causing a current flow on an adjacent pair). · The twisting of wires into pairs helps reduce crosstalk between pairs. · Each pair of wires is twisted at a different rate to reduce crosstalk between pairs. · Crosstalk is often introduced within connectors, where the twists are removed to add the connector. Crosstalk can also occur where wires are crushed or where the plastic coating is worn. There are several forms of crosstalk: · Near-end crosstalk (NEXT) is measured on the same end as the transmitter. For example, when a signal is sent on one wire pair, near-end crosstalk measures the interference on an adjacent wire pair at the same connector end. · Far-end crosstalk (FEXT) is measured on the end without the transmitter. For example, when a signal is sent on one wire pair, far-end crosstalk measures the interference on an adjacent wire pair at the opposite connector end. Alien crosstalk is introduced from adjacent, parallel cables. For example, a signal sent on one wire pair causes interference on a wire pair that is within a separate twisted pair cable bundle.
Twisted Pair Disadvantages
EMI and Eavesdropping
Each type of UTP cable can be substituted
Each type of UTP cable can be substituted for any category below it, but never for a category above. For example, Cat 6 can be substituted for a standard requiring Cat 5e. However, neither Cat 5 nor Cat 3 can be used in a situation where Cat 6 is required. The exception is Cat 7 cabling, and then only when Cat 7 is terminated with TERA connectors.
Electromagnetic Interference (EMI)andRadio Frequency Interference (RFI)
Electromagnetic interference and radio frequency interference are external signals that interfere with normal network communications. Common sources of EMI/RFI include nearby generators, motors (such as elevator motors), radio transmitters, welders, transformers, and fluorescent lighting. To protect against EMI/RFI: · Use fiber optic instead of copper cables. Fiber optic cables are immune to EMI/RFI. · Use shielded twisted pair cables. Shielded cables have a metal foil that encloses all of the wires. Some cables might also include a drain wire that is a bare wire outside of the foil, but within the cable jacket. The drain wire can be grounded to help absorb EMI/RFI. · Avoid installing cables near EMI/RFI sources.
Twisted Pair Advantages
Flexibility, Cost, Ease of Use, works with newer protocols
Open Impedance Mismatch (Echo)
Impedance is the measure of resistance within the transmission medium. · Impedance is measured in ohms (Ω). · All cables must have the same impedance rating. The impedance rating for the cable must match the impedance of the transmitting device. · Impedance is mostly a factor in coaxial cables used for networking. Be sure to choose cable with the correct rating (50 or 75 ohm) based on the network type. Never mix cables with different ratings. · When signals move from a cable with one impedance rating to a cable with another rating, some of the signal is reflected back to the transmitter, distorting the signal. With video (cable TV), impedance mismatch is manifested as ghosting of the image. · Cable distance does not affect the impedance of the cable.
As a network administrator, you are often responsible for both data and telephone wiring for your organization.
In this lesson, you will learn about: · Demarcation points · Main distribution frames (MDFs) and intermediate distribution frames (IDFs) · Punch down blocks · Patch or distribution panels · MDF, IDF, and patch panel documentation
Signal Loss
Light signals being transmitted through a fiber optic cable experience attenuation, or signal loss, as they pass through the cable due to: · Reflection: A measurable amount of light is reflected when it hits the ends of the cable. Much of a cable's reflection loss occurs at each cable connection. When the light hits the boundary between the core and the cladding, it is reflected back into the core. There is minor loss to the signal when this occurs, but it contributes to overall signal loss. · Refraction: If the light hits the boundary between the core and the cladding at too steep of an angle, the light is refracted into the cladding instead of reflected back into the core, causing signal loss. Some fiber optic cables are doped with impurities near the edge of the fiber so that the signals are bent instead of reflected back to the center of the core. The loss due to this refraction is minor when compared with the benefits of confining the light to the center of the core. · Scattering: Impurities in the fiber core can cause light to scatter. Some of the light continues down the fiber. The light that is scattered backwards contributes to the signal loss. · Absorption: Impurities in the fiber can also absorb the light, converting it to another form of energy, like heat. This is a major cause of signal loss.
Media Adapters and Transceivers
Many network switches and routers allow you to insert a transceiver such as a gigabit interface converter (GBIC) in an empty slot to convert the interface from copper wiring to fiber optic. Other devices use a small form-factor pluggable (SFP) transceiver to accomplish the same goal. Several issues can occur when using these and other fiber optic media adapters: · Some GBIC/SFP modules use multimode fiber, while others use single-mode. Make sure that you use the correct type of fiber optic cable and connector required by the specific adapter. Media adapter modules malfunction on occasion. If you have lost connectivity on one of these links, ensure that the adapter module is working correctly.
Multi-Mode vs. Single-Mode
Multi-mode and single-mode fiber cables are not interchangeable.
Known Good Spares
One valuable troubleshooting method is to keep a set of components that you know are in proper functioning order. If you suspect a problem in a component, swap it with the known good component. If the problem is not resolved, troubleshoot other components. Examples of using this strategy include the following: · Changing the drop cable that connects a computer to the network · Replacing a NIC with a verified working NIC Moving a device from one switch port to another
Punch Down Blocks
Punch down blocks are the predecessors to patch panels. They are commonly used to support low-bandwidth Ethernet and telephony wiring.
Cat 3
RJ45, Cat 3 is designed for use with 10-megabit Ethernet (10BASE-T) or 16-megabit token ring.
Troubleshooting fiber optic wiring is more complex than troubleshooting copper network wiring. To function properly, fiber optic cabling must be created, installed, and maintained very carefully.
Several important factors that can affect fiber optic performance are listed in the following table.
Damaged and Mismatched Cables
Several issues can occur when you are working with fiber optic cabling. · Fiber optic cabling is much less forgiving of physical abuse than copper wiring. The fiber core is fragile and can be easily damaged by rough handling. For example, bending a fiber cable at too tight of a radius will break the core. Wavelength mismatch will cause serious issues with fiber optic cables. You cannot mix and match different types of cable. For example, if you connect single-mode fiber to multi-mode fiber, you will introduce a catastrophic signal loss of up to 99%. Even connecting cables of the same type that have different core diameters can cause a loss of up to 50% of the signal strength.
Connectors
Several issues can occur when you are working with fiber optic connectors. · For light to pass through a fiber optic connector, the fiber within the jack must line up perfectly with the fiber in the connector. Using the wrong connector will result in misaligned fibers, disrupting the light signal even if the connector is successfully locked into the jack. · Dirty connectors can also impede or disrupt the light signal, so it's important that they are kept clean. Several cleaning methods can be used with fiber optic connectors: oFor connectors where the ferrule protrudes out of the connector, such as the FC connector, you can wipe the end of the ferrule with a lint-free cloth that has a small amount of denatured alcohol applied. Immediately wipe the ferrule dry with a dry lint-free cloth. oFor fiber optic connectors where the end of the ferrule is less accessible, you must use a specialized cleaning tool. Some cleaning tools allow you to plug in the fiber optic cable and then clean it by pumping the tool's handle. To clean the jacks on fiber optic network interfaces, you can purchase a specialized fiber optic cleaning stick to remove foreign material.
T568A
Standards for wiring twisted-pair network cabling and RJ-45 connectors and have the green pair connected to pins 1 and 2 and the orange pair connected to pins 3 and 6.
Main Distribution Frames (MDFs)
Strictly speaking, a main distribution frame (MDF) is a frame or rack that is used to interconnect and manage telecommunication wiring in a building. It functions like an old-time telephone switchboard, where operators used connecting wires to route telephone calls. Today's MDF describes the room that houses the traditional MDF along with networking patch panels. Often, rack mounted equipment is also housed in an MDF. · A traditional MDF may exist in a dedicated room or a within rack space in a datacenter. · An MDF is usually located on the bottom floor or basement of a building. · All internet or WAN demarcation points are normally near or within the MDF.
Cat 7
The Cat 7 standard was ratified years before the Cat 6a standard to support 10-Gbps Ethernet (10GBASE-T). It requires shielding on each twisted pair and the cable as a whole. It also specifies the GG45 or TERA connectors.
RJ48c
There is another connector type called RJ48c that is almost identical to RJ45. RJ48c uses the same connector as an RJ45, but it is used for specific WAN connections, such as a T1 line, and is wired differently.
Troubleshooting physical connectivity problems is much easier if you use the appropriate troubleshooting tool.
Troubleshooting physical connectivity problems is much easier if you use the appropriate troubleshooting tool.
Constructing Cables with RJ45 Connectors
Use a crimping tool designed for RJ45 connectors. · Determine whether the cable wires have solid cores or stranded cores. oBe sure to use the correct RJ45 connector type, solid or stranded. oUse solid core cables for longer runs inside walls or the ceiling. oUse stranded core wires for patch cables and for drop cables where frequent movement occurs and flexibility is needed. · To reduce crosstalk, keep the pairs twisted as much as possible right up to the connector. oUnderstand that Cat 6- and Cat 6a-compliant cables may not perform at the 10 Gbps speed if the pairs are not twisted right up to the connector.
Transceiver Mismatch
Well-manufactured network devices have interfaces that can be tailored to different cable types, protocols, and speeds. This is done by connecting a hot swappable transceiver to the interface. When connecting one network device to another, matching transceivers must be used. For twisted pair cabling, a mismatch in speed is a common issue.
Polishing
Whenever a connector is installed on the end of fiber optic cable, a degree of signal loss occurs. This is called insertion loss. Additionally, some of the light that is lost is reflected directly back down the cable, toward the source. This is called back-reflection, or optical return loss (ORL). It can corrupt the data being transmitted and even damage the transmitter. For a connector to work properly, there must be as little insertion loss and ORL as possible. The better the polish on the connector, the better the light will pass through without reflection. Fiber optic equipment manufacturers rate their connectors using the following polish grading designations: · Physical contact (PC) polishing is usually used with single-mode fiber. The ends of the fiber are polished with a slight curvature so that when the cable end is inserted into the connector, only the cores of the fiber actually touch each other. · Super physical contact (SPC) and ultra physical contact (UPC) polishing use a higher grade of polish and have more of a curvature than PC polishing, further reducing ORL reflections. · Angled physical contact (APC) polishing is used to reduce back reflection as much as possible. An APC connector has an eight-degree angle cut into the ferrule, which prevents reflected light from traveling back down the fiber. Any reflected light is bounced out into the cable cladding instead. You can only use angle-polished connectors with other angle-polished connectors. Using an angle-polished connector with a non-angle-polished connector causes excessive insertion loss. APC connectors are colored green to prevent them from being mixed with non-APC connectors.
Wire Stripper, Snips, and Crimpers
Wire strippers remove the protective sheath of a cable in order to expose the conductive wire. · Wire strippers are rated to specific gauge (cable width) ranges. · Most wire strippers are combination tools (they can strip, cut, and crimp cables). · Almost all wire strippers have multiple holes or can be adjusted for specific cable sizes. A crimping tool is used to attach connectors to wires. Some crimpers are designed for power connections. A special crimper is used to attach RJ45 connectors to twisted pair cables. Snips are cutting tools used to cut cables or wires to a specific length or to remove damaged sections. A diagonal cutter is an example of a snip tool. Whenever possible, use a wire stripper instead of snips to strip a cable. Wire strippers are specifically designed to cut only the protective sheath without cutting the internal wire.
Specially manufactured twisted pair cables are used in plenum and riser spaces
· A plenum space is a part of a building that provides a pathway for the airflow needed by heating and air conditioning systems, such as above a dropped ceiling or below a raised floor. · Plenum rated cables use insulation that is fire resistant and non-toxic when burned. · Plenum rated cables must be used in plenum spaces. · Riser rated cables are designed for installations that run between floors. · Riser requirements are not as strict as plenum requirements oPlenum rated cables can be used in riser spaces. Riser rated cables must never be used in plenum spaces
Several physical cable attributes can contribute to signal loss:
· Cable length: while higher quality cables will carry light signals further, the longer the cable, the more signal absorption and the greater the signal loss. · Connectors: every connector will cause some level of signal loss, mostly due to reflection. While patch cables at each end of a run are to be expected, you should minimize any other connections. · Splices: there are tools that you can use to splice a cut fiber optic cable. However, the signal loss from a splice is comparable to the signal loss from a connector. · Bends: micro bends in the cable due to things such as temperature change or manufacturing anomalies can cause signal loss. While you have little control over micro bends, even macro bends, those detected by the human eye, can contribute to signal loss. The straighter the fiber optic cable, the less the signal loss. You can estimate how much signal loss (measured in dB) you should reasonably expect in a given run of fiber optic cabling. Signal loss is calculated by summing the average loss of all the components used in the cable run to generate an estimate of the total attenuation that will be experienced end-to-end. This estimate is called a loss budget.
When calculating a loss budget for a segment of fiber optic cable, use the following guidelines:
· Connectors: 0.3 dB loss each · Splices: 0.3 dB loss each · Multi-mode cabling: o3 dB loss per 1000 meters when using an 850 nm light source o1 dB loss per 1000 meters when using a 1300 nm light source · Single-mode cabling: o0.5 dB loss per 1000 meters when using a 1310 nm light source o0.4 dB loss per 1000 meters when using a 1550 nm light source The total attenuation should be no more than 3 dB less than the total power at the transmission source. This is called the link-loss margin. For example, if the total power output at the transmission source of a cable run is 15 dB, then the total attenuation over the cable run should not exceed 12 dB. This ensures that the cable will continue to function as its components (such as the LED light transmitters and connectors) degrade with age and use.
Single-Mode Fiber
· Data transfers through the core using a single light path. · The core diameter is around 8-10.5 microns. · Cable lengths can extend a great distance. · There is less modal dispersion, so bandwidths can be higher. · Higher-cost electronics are required to send signals down a single path. Optimized for 1310 nm and 1550 nm light sources.
Multi-Mode Fiber
· Data transfers through the core using multiple light paths. · The core diameter is around 50 to 100 microns. · There is more modal dispersion due to the multiple paths. · Cable lengths are limited in distance and are dependent on bandwidth. · Higher light gathering capacity simplifies connections and allows lower-cost electronics. Optimized for 850 nm and 1300 nm light sources.
Documentation Keeping an MDF or IDF organized is a major challenge. One key to doing so is proper documentation. Here are some guidelines:
· Develop a naming convention and use it to label cables, wall jacks, patch panel ports, network devices, and racks. · Record names in tables and diagrams. oInclude location, installation dates, cable lengths, and cable grades. oConsider using documentation software. Perform an internet search for cable plant documentation software or cable management software to view available options.
GG45
· Has eight connectors. · Supports four pairs of wires. · Backwards compatible with RJ45. Four additional conductors in the corners of the connector that duplicate and replace the four inner pins on the RJ45.
TERA
· Has eight connectors. · Supports four pairs of wires. · Incompatible with RJ45 and GG45. Does not require special tools to install.
RJ45
· Has eight connectors. · Supports up to four pairs of wires. · Uses a locking tab to keep the connector secure in an outlet. · Used for Ethernet and some token ring connections.
Coaxial cable advantages
· Highly resistant to EMI (electromagnetic interference) Highly resistant to physical damage
Crossover
· If a network devices such as a hub or switch does not have an uplink port, use a crossover cable when connecting it to another network device. · You can also connect one computer directly to another using a crossover cable. · A crossover cable maps the transmit pins on one end of the cable with the receive pins on the other end. · You can easily create a crossover cable as follows: oUse the T568A standard to attach an RJ45 connector to one end. oUse the T568B standard to attach an RJ45 to the other end.
BNC coaxial cable connector
· Molded onto the cable Used in 10Base2 Ethernet networks
coaxial cable disadvantages
· More expensive than UTP · Inflexible construction (more difficult to install) Unsupported by newer networking standards
Straight-Through
· Most twisted pair cables are manufactured as straight-through cables. · Connect computers to a hub or switch with a straight-through cable. · The pinout order on a computer's NIC is different than the pinout order on the hub or switch port. Transmit pins of the NIC map to the receive pins on hub or switch and vice versa.
Power over Ethernet (PoE) Cabling
· Power can be supplied through one of the unused pairs of wires in 10- and 100-Megabit Ethernet. · Power can also be supplied using one of the data wires. · Many network switches have provide the option to supply PoE. · PoE injection devices can be added to the middle of the cable span.
When working with fiber optic cabling, you can use media converters to switch between different network media. For example, you can convert:
· Single-mode fiber to copper Ethernet wiring · Multi-mode fiber to copper Ethernet wiring · Single-mode or multi-mode fiber to coaxial wiring · Single-mode fiber to multi-mode fiber
While a NID can be a passive demarc that organizes the cable and connections, a more intelligent NID, known as smartjack, may be provided by the LEC.
· Smartjacks are maintained by the LEC. · Smartjacks are typically used for more complex services, such as a T1 line. · Smartjacks can provide signal conversions, buffer signals, and regenerate signals. · Smartjacks may provide diagnostic capabilities for the LEC. oThe loopback capability can be used to test signals by transmitting them back to the LEC. oAlarm indicators can report trouble to the LEC. oIndicator lights can show the configuration and status of the Smartjack.
Twisted pair cables can be solid or stranded.
· Solid wires conduct electrical signals better, but are prone to break when they are repeatedly bent. · Stranded cables are more flexible, but don't carry signals as well. · Use solid cables in permanent and semi-permanent installations. · Use stranded cables for patch cords and when cables are frequently moved.
Demarcation Points
· The demarc (short for demarcation point) is the line that marks the boundary between the telco equipment or cable and your private network or telephone system. · The demarc is also called the minimum point of entry (MPOE) or the end user point of termination (EU-POT). · In businesses, the demarc is typically located on the bottom floor of a building, just inside the building, and identified by an orange plastic cover on the wiring component. · In residential buildings, the demarc is often a small box on the outside of the house. · The demarc may be: oA box on the wall with a simple RJ45 connection oA 50-pin RJ21 connector oA fiber optic connection oA port on a network interface device (NID) · If needed, a demarc extension can be used to move the demarc to another location in a building. For example, if your organization uses only one floor of a building, you will want the demarc where it is not exposed to other organizations. oYou are responsible for installing the demarc extension, but the LEC might do it for an additional charge. · Normally, the LEC is responsible for all equipment on one side of the demarc, and the customer is responsible for all equipment on the other side of the demarc.
There are two light source technologies prevalent in fiber optic communications, diode laser and high-radiance light-emitting diode (LED). The light produced by these technologies is in the infrared region of the light spectrum.
· The most common wavelengths used in fiber optics are 850 nm, 1300 nm, 1310 nm and 1550 nm. oIn glass, these longer wavelengths have lower attenuation or signal loss due to scattering. oAttenuation in glass due to light absorption for these wavelength is almost zero. · Multi-mode fiber is designed to operate at 850 nm and 1300 nm. · Single-mode fiber is optimized for 1310 nm and 1550 nm.
Use a punch down tool to insert wires into 66 or 110 blocks.
· The punch down tool pushes the wire into the block and cuts off the excess wire. · Be sure to position the blade on the side of the clip toward the end of the wire. · The blade for a 66 block is straight, while the blade for a 110 block is notched.
Wave Division Multiplexing (WDM) joins several light wavelengths (colors) onto a single strand of fiber.
· This enables light signals in both directions across a single fiber. · Today's systems can easily multiplex 160 signals. · WDM is mostly used by long-haul and high-speed providers. · Most WDM systems are designed to be used with single-mode fiber.
Fiber Advantages
· Totally immune to EMI (electromagnetic interference) · Highly resistant to eavesdropping · Supports extremely high data transmission rates Allows greater cable distances without a repeater
F-Type coaxial cable connector
· Twisted onto the cable or installed using a compression tool · Used to create cable and satellite TV connections Used to connect a cable modem to a broadband cable connection
Coaxial cable has the following components:
· Two concentric metallic conductors oThe inner conductor is a solid wire made of copper or copper-coated tin. oThe outer mesh conductor, or shield, is made of aluminum or tin-coated copper. · An PVC plastic insulator, which surrounds the inner conductor and insulates the signal from the mesh conductor. · A PVC plastic cable sheath, or jacket, that surrounds and protects the wire.
Fiber FC Connector
· Typically used with single-mode cabling. · Each wire has a separate connector. · Uses a threaded connector. Designed to stay securely connected in environments where it may experience physical shock or intense vibration.
Patch or Distribution Panels In an MDF or IDF, punch down blocks are rarely used for network cabling. Instead, twisted pair cables are terminated at a patch panel.
· Typically, individual four-pair cables are used rather than 25-pair or 100-pair cables. This takes advantage of cable shielding and minimizes cross-talk. oIn large applications, bundles of 25- and 100-pair cables can be used for VCCs and HCCs. However, they should be certified to support the desired network speed. Twisted pairs are connected at the rear of the panel with connections similar to punch down blocks. A special tool is usually required.
Fiber LC (lift and click or little connector) Connector double strand
· Used with single-mode and multi-mode cabling. · Composed of a plastic connector with a locking tab that is similar to a RJ45 connector. · A single connector with two ends keeps the two cables in place. · Uses a ceramic ferrule to ensure proper core alignment and to prevent light ray deflection. · Is half the size of other fiber optic connectors. Mnemonics are Lift-and-Click or Little Connector
Fiber MTRJ Connector double strand
· Used with single-mode and multi-mode cabling. · Composed of a plastic connector with a locking tab. · Uses metal guide pins to ensure that it is properly aligned. · A single connector with one end holds both cables. Uses a ceramic ferrule to ensure proper core alignment and prevent light ray deflection.
Fiber ST (set twist) connector single strand
· Used with single-mode and multi-mode cabling. · Has a keyed bayonet-type connector. · Also called a push-in and twist connector. · Each wire has a separate connector. · Nickel plated with a ceramic ferrule to ensure proper core alignment and prevent light ray deflection. Mnemonics are Set-and-Twist or Straight Tip.
Fiber SC (set click) Connector single strand
· Used with single-mode and multi-mode cabling. · Has a push-on/pull-off connector that uses a locking tab to maintain connection. · Each wire has a separate connector. · Uses a ceramic ferrule to ensure proper core alignment and prevent light ray deflection. · Mnemonics are Set-and-Click or Square Connector.
Fiber Disadvantages
· Very expensive · Difficult to work with Special training required to attach connectors to cables
