Day 5

Wires

Why wire?• Conducts Electricity and directs it

to a location.• Cheap!• Easy to run

Quality of wire• Thickness/materials of wire

dictates how much resistance it will create– This gives us signal loss & noise– AWG (American Wire Gauge)

• Smaller numbers are fatter.• Cat 5 = 24AWG• Home wiring 12AWG

UTP• Unshielded Twisted Pair

– Pair = 2 wires – Twisted means they are…twisted– Unshielded means no tin foil

Pairs• Today’s data networks require 2

pairs to transmit data. – 2 wires to send– 2 wires to receive

• Hence network cable must have at least 2 pairs.– Typically they now have 4 pairs (8

wires) because we don’t know what new technology will come out later.

Cats• Category of wire

1. No longer used2. No longer used3. Telephone wire, capable of 10Mb for

100M4. No longer used5. Standard network cable, capable of

1GB for 100M5e. 1GB for 100M6. 1GB for 100M7. 10GB for 100M (Shielded)

Creating a Patch Cable• A standard patch cable will have the

same wire colors on each end:– White/Orange, Orange, White/Green, Blue,

White/Blue, Green, White/Brown, Brown.– Orange is transmit (white/orange +)– Green Receive (white/green +)

• A “Cross Over” cable will have the above schema on one end of the cable, and a different one on the second end.– White/Green, Green, White/Orange,

White/Brown, Brown, Orange, Blue, White/Blue

– For 10 or 100 MB it is sufficient to put the green and orange wires. For GB you need all 4 pairs.

RJ45, RJ11• RJ45 is the name of the ends used

in today’s networks• RJ11 is a phone end• Sockets are sold as RJ11 or RJ45

depending on your need.– Typically called keystone jacks, used

on multi-outlet faceplates.– Are also sold as individual face plates

Coaxial• Very well shielded• Lower loss• Harder to work with• Ends are either Coax Ends or BNC

connectors.• Used for video because of

bandwidth, sometimes used in LANs– Fading away in favor of Cat5 & Fiber.

Fiber• Single Optical fiber can only

transmit data in 1 direction at a time.

• Hence 2 are needed to make a connection.

Fiber Advantages• Advantages

– High bandwidth capabilities– Low signal loss– Security

• Disadvantages– Difficult to put ends on, connect– Cost– Can be broken if pulled on etc.

Light Source• LED

– Cheap, easy. – Lower data rates, more light loss

• Laser– Very focused, low loss, high speed.

Bandwidth• Fiber optics can be used to

transmit data over 100 miles without repeaters

• In theory can be used to transmit data at 100Tb/s– Today you can buy 10Gbps network

gear• Probably maxes out around 3Gb