Primary Cable Types

Primary Cable Types

• Coaxial Cable
• Twisted-pair
• UTP - Unshielded Twisted Pair
• STP - Shielded Twisted Pair
• Fiber-optic

Coaxial Cable

• Consists of a solid or stranded copper core surrounded by insulation, a braided shield and an insulating jacket.

• Braided shield prevents noise and crosstalk.
• More resistant to interference and attenuation than twisted pair cabling.
• Both thin and thick cables can use (see pp. 80-81 for pics)
• BNC cable connectors,
• BNC barrel connectors
• BNC T connectors
• BNC terminators.
• Plenum (fire resistant) graded cable can be used in false ceilings of office space or under the floor.
• Can transmit data, voice and video.
• Offers moderate security ----> better than UTP/STP

Thinnet - RG-58 cable

• called
• 0.25" thick.
• Uses
• BNC twist connector,
• BNC barrel connectors
• BNC T connectors
• 50 ohm terminators
• Can carry signals 185 meters or 607 feet.
• Types: (pics on page 78)

Coaxial Cable Types

RG-8 and RG-11	Thicknet (50 ohms)
RG-58 Family
RG-58 /U	Solid copper (50 ohms)
RG-58 A/U	Thinnet, Stranded copper (50 ohms)
RG-58 C/U	Thinnet, Military grade (50 ohms)
RG-59	Broadband/Cable TV (75 ohm) video cable
RG-62 A/U	ARCnet cable (93 ohm) RG-62 A/U is the standard ARCnet cable, but ARCnet can use fiber optic or twisted pair.

• each cable must have a terminator whose impedance matches the cable type
• impedance = current resistance measured in ohms
• terminators are resistors that prevent signal bounce or echo.

Here are some limitations of 10Base2 Ethernet:

• Length of trunk segment may be up to 607 feet.
• A maximum of 30 workstations is allowed per trunk.
• There may be no more than 1024 workstations per network.
• Entire network trunk length can't exceed 3035 feet (925 meters)
• The minimum cable length between workstations is 20 inches.
• The Ethernet 5-4-3 Rule for connecting segments is 5 trunk segments can be connected, with 4 repeaters or concentrators, with no more than 3 populated segments (on coaxial cable).

Thicknet - RG-8 and RG-11 coaxial cable

• 0.5" thick
• used for 10Base5 networks, linear bus topology
• transmits at 10 Mbps
• Uses DIX or AUI (Attachment Unit Interface) connector - also known as DB-15 connector to connect to external transceivers.
• Vampire taps are used to attach a transceiver to the thicknet trunk.
• Can carry signals 500 meters or 1640 feet.
• much less flexible and far more bulky and harder to install than thinnet
• better security than thinnet
• better resistance to electrical interference than thinnet.
• MORE expensive than thinnet.

Twisted-Pair Cable

• Consists of two insulated copper wires twisted around each other.
• Twisting cancels out electrical noise from adjacent pairs (crosstalk) and external sources.
• Uses RJ-45 telephone-type connectors (larger than telephone and consists of eight wires vs. Telephone's 4 wires).
• Generally inexpensive.
• Easy to install.

Unshielded Twisted Pair (UTP)

• Maximum cable length is 100 meters or 328 feet (10BaseT).
• Types:
1. Cat 1 Voice grade telephone cable.
2. Cat 2 Data grade up to 4 Mbps, four twisted pairs.
Category 3 and above is needed for Ethernet networks. Cat 3, 4, and 5 use RJ-45 connectors
1. Cat 3 Data grade up to 10 Mbps, four pairs w/3 twists/ft.
2. Cat 4 Data grade up to 16 Mbps, four twisted pairs.
3. Cat 5 Data grade up to 100 Mbps, four twisted pairs.
This is the cheapest cable to put in. Exam questions ALWAYS take this as a given.

Here are some limitations of 10BaseT Ethernet:

• Workstations may be no more than 328 feet from the concentrator port.
• 1,023 stations are allowed on a segment without bridging.
• The minimum cable length between workstations is 8 feet.

Other Drawbacks

• UTP is particularly susceptible to crosstalk, which is when signals from one line get mixed up with signals from another.
• easily tapped (because there is no shielding)
• 100 meters is shortest distance => attenuation is the biggest problem here.

Shielded Twisted Pair (STP)

• Uses a woven copper braid jacket and a higher quality protective jacket. Also uses foil wrap between and around the wire pairs.
• Much less susceptible to interference and supports higher transmission rates than UTP.
• Shielding makes it somewhat harder to install.
• same 100 meter limit as UTP.
• harder to tap
• used in AppleTalk and Token Ring networks

Fiber Optic Cable

•  Consists of a small core of glass or plastic surrounded by a cladding layer and jacket.
• Fibers are unidirectional (light only travels in one direction) so two fibers are used, one for sending and one for receiving. Kelvar fibres are placed between the two fibres for strength.
• Good for very high speed, long distance data transmission.
• NOT subject to electrical interference.
• Cable can't be tapped and data stolen => high security
• Most expensive and difficult to work with.
• Immune to tapping.
• can transmit at 100 Mbps and way up to 2 Gbps
• up to 2000 meters without a repeater.
• Supports data, voice and video.
• needs specialized knowledge to install => expensive all round.

Cable Type Comparisons
Type	Speed	Distance	Installation	Interference	Cost	# of nodes per segment	# of nodes per network
10BaseT	10 Mbps	100 meters	Easy	Highly susceptible	Least expensive	1 computer
100BaseT	100 Mbps	100 meters	Easy	Highly susceptible	More expensive than 10BaseT
STP	16 to 155 Mbps	100 meters	Moderately Easy	Somewhat resistant	More expensive than Thinnet or UTP
10Base2	10 Mbps	185 meters	Medium Difficulty	Somewhat resistant	Inexpensive	30	1024
10Base5	10 Mbps	500 meters	More difficult than Thinnet	More resistant than most cable	More expensive than most cable	100	300
Fiber Optic	100 Mbps to 2 Gbps	2000 meters	Most difficult	Not susceptible to electronic interference	Most expensive type of cable

Signal Transmission

Baseband Transmission -- Digital

• Baseband transmission uses digital signaling over a single frequency.
• Entire communication channel is used to transmit a single signal.
• Flow is bi-directional. Some can transmit and receive at the same time.
• Baseband systems use repeaters to strengthen attenuated signals.

Broadband Transmission -- Analog

• Broadband uses analog signaling over a range of frequencies.
• Signals are continuous and non-discrete.
• Flow is uni-directional and so two frequency channels or two separate cables must be used.
• if enough bandwidth is available, multiple analog transmission systems such as cable TV AND network transmissions can be on the same cable at the same time.
• if this is the case, ALL devices must be tuned to use only certain frequencies
• Uses amplifiers for signal regeneration.

Helpful mnemonic to remember the difference:

Baseband is "BEDR"
Bidirectional
Entire channel taken up
Digital
Repeaters used to strengthen signal

IBM Cabling

• Uses AWG standard wire size.
• Connected with proprietary IBM unisex connectors.
• Defines cables as types

Type 1	STP  (Shielded twisted-pair)	used for computers and MAU's. 101 m	These three cable types can be used in Token Ring Networks	16 Mbps 260 computer limit
Type 2	STP, Voice and data	100 m
Type 3	UTP; Voice grade	45 m Most common Token Ring Cable		4 Mbps 72 computer limit
Type 5	Fiber-optic	industry standard
Type 6	STP; Data patch	used to connect MSAU's together used to extend Type 3 cables from one computer to the MSAU
Type 8	STP Flat; Carpet grade	Limited to 1/2 the distance of Type 1 cable
Type 9	STP; Plenum grade	used under floors or in ceiling space