Cabling
Characteristics of Copper Cabling
Copper cabling is the most common type of cabling used in networks today. It is inexpensive, easy to install, and has low resistance to electrical current flow.
Limitations:
- Attenuation – the longer the electrical signals have to travel, the weaker they get.
- The electrical signal is susceptible to interference from two sources, which can distort and corrupt the data signals (Electromagnetic Interference (EMI) and Radio Frequency Interference (RFI) and Crosstalk).
Mitigation:
- Strict adherence to cable length limits will mitigate attenuation.
- Some kinds of copper cable mitigate EMI and RFI by using metallic shielding and grounding.
- Some kinds of copper cable mitigate crosstalk by twisting opposing circuit pair wires together.
Types of Copper Cabling
Unshielded Twisted Pair (UTP)
- UTP is the most common networking media.
- Terminated with RJ-45 connectors
- Interconnects hosts with intermediary network devices.
Key Characteristics of UTP
1.The outer jacket protects the copper wires from physical damage.
2.Twisted pairs protect the signal from interference.
3.Color-coded plastic insulation electrically isolates the wires from each other and identifies each pair.
Shielded Twisted Pair (STP)
Better noise protection than UTP
More expensive than UTP
Harder to install than UTP
Terminated with RJ-45 connectors
Interconnects hosts with intermediary network devices
Key Characteristics of STP
1.The outer jacket protects the copper wires from physical damage
2.Braided or foil shield provides EMI/RFI protection
3.Foil shield for each pair of wires provides EMI/RFI protection
4.Color-coded plastic insulation electrically isolates the wires from each other and identifies each pair
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Coaxial Cable
Consists of the following:
1.Outer cable jacket to prevent minor physical damage
2.A woven copper braid, or metallic foil, acts as the second wire in the circuit and as a shield for the inner conductor.
3.A layer of flexible plastic insulation
4.A copper conductor is used to transmit the electronic signals.
There are different types of connectors used with coax cable.
Commonly used in the following situations:
Wireless installations -attach antennas to wireless devices
Cable internet installations -customer premises wiring
Properties of UTP Cabling
UTP has four pairs of color-coded copper wires twisted together and encased in a flexible plastic sheath. No shielding is used. UTP relies on the following properties to limit crosstalk:
- Cancellation – Each wire in a pair of wires uses opposite polarity. One wire is negative, the other wire is positive. They are twisted together and the magnetic fields effectively cancel each other and outside EMI/RFI.
- Variation in twists per foot in each wire – Each wire is twisted a different amount, which helps prevent crosstalk amongst the wires in the cable.
UTP Cabling Standards
Connectors
Straight-through and Crossover UTP Cables
Properties of Fiber-Optic Cabling
- Not as common as UTP because of the expense involved
- Ideal for some networking scenarios
- Transmits data over longer distances at higher bandwidth than any other networking media
- Less susceptible to attenuation, and completely immune to EMI/RFI
- Made of flexible, extremely thin strands of very pure glass
- Uses a laser or LED to encode bits as pulses of light
- The fiber-optic cable acts as a wave guide to transmit light between the two ends with minimal signal loss
Types of Fiber Media
Single-Mode Fiber
- Very small core
- Uses expensive lasers
- Long-distance applications
- up to 100 Gbps over 100 KM
Multimode Fiber
- Larger core
- Uses less expensive LEDs
- LEDs transmit at different angles
- Up to 10 Gbps over 550 meters
Fiber-Optic Connectors
Straight-Tip (ST)
Subscriber Connector (SC)
Lucent Connector (LC) Simplex
Duplex Multimode LC
Fiber versus Copper
