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2. Network Media—Copper Core Cable. Grades. Labs. Network Media. Analog and Digital Signals. Analog signal —electronic signal that varies in values Series of slopes. Analog and Digital Signals. Digital signal —electronic signal that has discrete values.
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2 Network Media—Copper Core Cable
Analog and Digital Signals Analog signal—electronic signal that varies in values Series of slopes
Analog and Digital Signals Digital signal—electronic signal that has discrete values. Rises and falls sharply at right angles; on and off, high and low
Frequency How electronic signals are measured
Attenuation Loss of signal strength All signals degenerate, lose amplitude Amplitude - The maximum voltage of electronic signal Amplitude can be increased with an amplifier
Latency Amount of time it takes for signal to travel from source to destination If latency exceeds its Time to Live (TTL), it will be removed from network
Data Transmission Bandwidth - measurement of the network media’s ability to carry data. Higher bandwidth = more data carried Measured in hertz (Hz)
Interference Undesired electromagnetic signal, distorts Can be picked up from motors, fluorescent lights, transformers… “noise”
Interference Crosstalk Interference from neighboring conductors inside the wire’s jacket Unwanted signals need to be removed, or filtered
Crosstalk Measurements Measured in decibels (dB) A unit of measurement that expresses the relationship of power between two forces Near-End Crosstalk (NEXT) A measurement of reflected loss at the near end or input end of a cable. Far-End Crosstalk (FEXT) A measurement of reflected loss at the far end or out put end of a cable
Crosstalk Measurements Equal Level Far-End Crosstalk (ELFEXT) A measurement calculated by measuring the effects of attenuation from the far end crosstalk measurement Alien Crosstalk (AXT) A measurement of noise introduced outside the cable jacket, typically caused by other network cables in close proximity.
Index Cards 1. Draw a large plus on one side, a large minus on the other 2. + side: write down the term you understand best. Explain in your own words what this term consists of. 3. – side: write down term you feel unclear about and questions you have about it 4. Share your plus and minus with 2-3 classmates
Data Transmission Baseband—One digital signal Data that is transmitted in digital signal using the entire bandwith of cable Broadband—Multiple analog signals Transmitting data in the form of analog signals at the same time.
Data Transmission Simplex—One direction Communication Example: Television station to television Full-duplex—Bi-directional and simultaneous communication between two devices. Example: Communication via telephone Half-duplex— Bi-directional communication that can only occur one direction at a time. Example: Communication via Walkie-talkie
Direct and Alternating Current Alternating current alternates between negative and positive charge Direct current is in one steady direction
Resistance and Impedance The longer the conductor, the greater the resistance (DC) and impedance (AC) Impedance increases as frequency increases Impedance decreases quality of data
Reflected Loss Transmitted in full-duplex mode Great amounts can disrupt communication
Crosstalk Type of interference Occurs when one pair of conductors imposes a signal on another pair of parallel conductors Created by magnetic induction An electrical phenomenon of current jumping from one conductor to another Network conductors, such as twisted pair, limit the effects by reducing contact between conductors
Copper Core Cable Describes the conductors diameter AWG rating
Twisted Pair Consists of four pairs of twisted conductors First introduced by telephone company Seven categories Classified as UTP (unshielded twisted pair) and STP (shielded twisted pair)
Terminating Resistor Must be electrically grounded at one end to prevent interference
10BaseT 100-Meter Rule The 100-meter length ensures that the cable on the network should not exceed 100 meters Repeater may be used to extend distance
IEEE 802.3 Media Access CSMA/CD (Carrier Sense Multiple Access with Collision Detection) ensures data delivery Workstation listens for traffic on network When network is silent, workstation transmits data If another workstation transmits data at same time, collision occurs Both workstations wait before retransmitting
IEEE 802.3 Wiring Connections 568A and 568B—Main twisted pair cable termination standards Straight-through and crossover—Common classifications of assembly Automatic Medium Dependent Interface Crossover (Auto-MDIX)—New standard introduced by HP
RJ-45 Connector Contains eight pins inside plastic housing Conductor pairs are untwisted so that each conductor can be inserted into one of the pin areas
Rollover Cable Uses an RJ-45 connector on each cable end Cisco rollover cable uses an RJ-45 on one end and a DB-9 serial cable on the other
Applied Networking What would happen if you used a crossover cable to connect access port 2X to a workstation?
Applied Networking On the hub shown, the cable connected to the Uplink port is a straight-through cable. If you were connecting this hub to another hub, would you connect the cable to the other hub’s Uplink port or to one of its access ports?
Applied Networking You have added a third workstation and a hub to an existing network of two workstations. The original workstations were connected to each other via a crossover cable. For all three workstations to communicate, you have connected them to the hub. However, when the network is running, you notice that a light above one of the access ports on the hub is lit red. What could be the problem?
Power over Ethernet (PoE) Cable used must be Cat 5 or better Two pairs of cables used for network communication, one pair used for electrical power Common PoE application is building and area security when electrical power is not available
IEEE 802.5 Describes Token Ring networks Uses the token passing media access method Configured in a ring topology
Wiring Faults Data cannot reach its destination Short Open Ground
Twisted Pair Wiring Fault Common problems that can occur when installing connectors on twisted pair cables Reversed pair Crossed pair Split pair
Applied Networking An analog signal produces 1000 cycles per second. What is the frequency of this signal? 1000