Cabling and connectors

Cat 6 RJ45

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 RJ45

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).

Cat 3 RJ45

Cat 3 is designed for use with 10-megabit Ethernet (10BASE-T) or 16-megabit token ring.

Cat 5 RJ45

Cat 5 supports 100-megabit Ethernet (100BASE-TX) and ATM networking. Cat 5 specifications also support gigabit (1000 Mb) Ethernet.

Cat 5e RJ45

Cat 5e is similar to Cat 5 but provides better EMI protection. It supports 100-megabit (100BASE-T) and gigabit (1000BASE-T) Ethernet.

Electromagnetic Interference (EMI) and Radio 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.

Advantages of twisted pair cabling include:

Flexibility--you can run twisted pair cabling around tight corners and other places where other types of network cable simply cannot go without being damaged. Cost--twisted pair cabling is less expensive than other types of network cabling. Ease of use--twisted pair cabling is easy to work with, and it's much easier to install compared to other types of network cabling. Works with newer protocols--newer, faster network protocols and standards have been designed to run on twisted pair cabling.

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: Use the T568A standard to attach an RJ45 connector to one end. Use the T568B standard to attach an RJ45 to the other end.

components of fiber optic cabling:

The core carries the signal. It is made of glass or plastic. The cladding maintains the signal in the center of the core as the cable bends. The sheathing protects the cladding and the core.

Fiber optic cabling offers the following 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

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

Smartjacks

maintained by the LEC. typically used for more complex services, such as a T1 line. provide signal conversions, buffer signals, and regenerate signals. provide diagnostic capabilities for the LEC. The loopback capability can be used to test signals by transmitting them back to the LEC. Alarm indicators can report trouble to the LEC. Indicator lights can show the configuration and status of the Smartjack.

Incorrect Termination

occurs when an incompatible or incorrect connector is used. This can result in reduced performance or complete connection loss.

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

Punch down blocks

predecessors to patch panels.

STP

shielded twisted pair. Shielding is electrically conductive foil or braided material that is wrapped around pairs of wires, around the overall cable, or both. Shielding helps to minimize crosstalk. The main purpose of shielding is to minimize the effects of EMI from external sources, such as fluorescent light ballasts. The shielding can be used as a ground. However, most shielded cables have a special grounding wire called a drain wire.

demarc

the line that marks the boundary between the telco equipment or cable and your private network or telephone system.

Attenuation

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.

RG-58

10Base2 Ethernet networking (also called thinnet) 50 ohms

Single-mode fiber is optimized for

1310 nm and 1550 nm.

Multi-mode fiber is designed to operate at

850 nm and 1300 nm.

The most common wavelengths used in fiber optics are

850 nm, 1300 nm, 1310 nm and 1550 nm.

Phone cable RJ11

A phone cable is used to connect a PC to a phone jack in a wall outlet to establish a dial-up internet connection. It is also used to connect a DSL modem to a telephone network. It has two pairs of twisted cable (a total of 4 wires).

RG-59

Cable TV and cable networking 75 ohms

RG-6

Cable TV, satellite TV, and cable networking 75 ohms

Single-Mode

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

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.

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. 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.

RJ11

Has four connectors. Supports up to two pairs of wires. Uses a locking tab to keep the connector secure in an outlet. Used primarily for telephone wiring.

Coaxial cable has the following advantages:

Highly resistant to EMI (electromagnetic interference) Highly resistant to physical damage

BNC

Molded onto the cable Used in 10Base2 Ethernet networks

Coaxial cable has the following 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.

Fiber optic cabling offers the following disadvantages:

Very expensive Difficult to work with Special training required to attach connectors to cables

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.

T568A

Pin 1: GW = White with green stripe Pin 2: G = Green Pin 3: OW = White with orange stripe Pin 4: B = Blue Pin 5: BW = White with blue stripe Pin 6: O = Orange Pin 7: BrW = White with brown stripe Pin 8: Br = Brown

T568B

Pin 1: OW = White with orange stripe Pin 2: O = Orange Pin 3: GW = White with green stripe Pin 4: B = Blue Pin 5: BW = White with blue stripe Pin 6: G = Green Pin 7: BrW = White with brown stripe Pin 8: Br = Brown

The following pins are used for a computer NIC:

Pin 1: Transmit +Pin 2: Transmit -Pin 3: Receive +Pin 6: Receive - Pins 4, 5, 7, and 8 are unused.

When working with fiber optic cabling, you can use media converters to switch between different network media.

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

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.

Disadvantages of twisted pair cabling include:

Susceptible to interference--the sheath around twisted pair cable is relatively thin, making it susceptible to EMI. Susceptible to eavesdropping--with the right equipment, you can pick up signals emanating from the wire.

Cat 7 GG45 TERA

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.

Coaxial cable has the following components:

Two concentric metallic conductors The inner conductor is a solid wire made of copper or copper-coated tin. The 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.

Twisted pair cables support

Two copper conductors form a path for an electrical signal with each wire carrying an equal but opposite signal. The wires are twisted to reduce crosstalk, which is the absorbed signals from another pair. The conductors are 22- to 24-gauge in thickness and are covered in plastic insulation. Pairs are color coded, bundled together, and covered in a plastic jacket or sheath. Most cables contain four twisted pairs. Cables may contain 25 or 100 pairs when used in larger wiring applications. Each pair within a length of cable are given a different number of twists to further reduce the effects of crosstalk.

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.

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

LC Connector

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.

MTRJ Connector

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.

ST Connector

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.

SC Connector

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.

66 block

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: In 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. With 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.

110 block

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. Place the first wire into the plastic slot on the 110 block. Insert a connecting block over the wire and slot. The connecting block has metal connectors that pierce the plastic cable sheath. Place 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: White wire with a blue stripe followed by the solid blue wire. White wire with an orange stripe followed by the solid orange wire. White wire with a green stripe followed by the solid green wire. White 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.

Coaxial cable

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.

intermediate distribution frame (IDF)

a smaller wiring distribution frame or rack within a building.

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.

Open Circuit

caused by incorrect wire positions on both connectors.

Crosstalk

interference that is caused by signals within the twisted pairs of wires. 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.

Open Impedance Mismatch (Echo)

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.

UTP

unshielded twisted pair. UTP cables are easy to work with and less expensive than shielded cables.

Specially manufactured twisted pair cables

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 Plenum rated cables can be used in riser spaces. Riser rated cables must never be used in plenum spaces.