3.2 Cables - Network, Copper, Optical

What is a cable?

A passive physical medium used to transmit data between connected devices.

What is a connector?

A passive physical medium that terminates a cable to provide connection between a port and a cable.

What are the three primary types of network cables?

Coaxial, Twisted-pair, and Fiber

Copper

Copper is the most common medium used in coaxial and twisted-pair cables. Used as the conductor for transmitting data using electrical pulses.

Twisted-pair cabling

Two wires with equal and opposite signals (Transmit+, Transmit- / Receive+, Receive-). Twist keeps wires constantly moving away from interference, the opposite signals are compared on the other end. Pairs in the same cable have different twist rates

Categories (cat cables)

Categories 1 to 8, All Cat cables from 2-8 composed of four twisted pairs, total 8 wires in one cable sheath.

What determines the speed of a cable?

Cables don’t have a speed, the encoding of electric signals sent over the cable determines the data transfer rate.

What standards determine the cable types?

Cables are manufactured to meet IEEE 802.3 Ethernet standards.

Copper Cable Categories (IEEE 802.3 Ethernet standards) [Ethernet Standard, Cable Category, Max Distance]

1000BASE-T, Category 5, 100 m

1000BASE-T, Category 5e (enhanced), 100

10GBASE-T, Category 6, Unshielded 55m, Shielded 100 m

10GBASE-T, Category 6A (augmented), 100 m

What are the two color coded standards used for RJ45 wiring components?

ANSI/TIA-568: T568A, T568B

(T568B is is most commonly used)

T568A

The T568A standard is gr/wh, gr, or/wh, bl, bl/wh, or, br/wh, and br.

T568B

The T568B standard is or/wh, or, gr/wh, bl, bl/wh, gr, br/wh, and br.

Coaxial cable

Single copper cable (wire conductor) contained in an inner insulation layer, further contained in a wire mush conductor (metal shielding) and surrounded by a out insulation layer (plastic jacket). Specified by Radio Guide system, RG-6 is used with satellite and cable modems, and RG-59 is used for cable television.

Shielded twisted pair

Additional shielding protection against interference, can shield each pair or the overall cable and requires the cable to be grounded. Used in Cat 7 and Cat 8 cables

Unshielded twisted pair

Most common twisted pair cabling, no additional shielding, just insulating layer around each wire and plastic jacket over whole cable

Outer Covering Cable Abbreviations

U → Unshielded, S → Braided Shielding, F → Foil Shielding

S/FTP → Braided shielding around cable and foil around pairs

F/UTP → Foil around cable and no shielding around pairs

(<Overall cable>/<Individual Pairs>TP)

What is direct burial?

Cables buried underground, should be STP with an extra waterproof sheathing around cable or filled with gel to repel water. Should be 6-8” underground in a protective PVC pipe and away from other electrical lines.

Plenum-rated

Plenum space is a dedicated space used for air circulation in a building, typically above the drop ceiling. A Teflon-type covering is used on cables that may be exposed to extreme heat or have the possibility of releasing gases into a ventilation system. Cable is not very flexible, low bend radius

Types of plenum-rated cable

Traditional cable jacket (non-plenum)- PVC (polyvinyl chloride)

Fire-rated, cable jacket (plenum-rated) - FEP (fluorinated ethylene polymer) or low smoke PVC

Optical cable

Uses visible spectrum light pulses for data transfer over small strings of flexible glass. Very difficult to monitor or tap, degrades very little over long distances, immune to RF interference

Single-mode fiber

A smaller core that carries only one light path, typically sourced via laser. Higher bandwidth and longer transmission distance (100km), but more expensive than multimode

Multimode fiber

A larger core that carries multiple light paths, sourced via LED or lasers. Limited bandwidth and shorter transmission distance (2km), but cheaper than single