Sem 2 Networking Programming Week 4 Physical Layer

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Questions and Answers

What is a limitation of electrical signals in copper cables?

They can travel long distances without attenuation

They are resistant to electromagnetic interference

They are susceptible to attenuation and interference (correct)

They are completely immune to crosstalk

Which type of copper cable provides better noise protection than UTP?

Coaxial cable

Fiber optic cable

Shielded Twisted Pair (STP) (correct)

Unshielded Twisted Pair (UTP)

What is a method to prevent crosstalk in UTP cables?

Twisting the circuit pair wires together (correct)

Increasing the cable length

Using a metallic shielding

Using a grounded shield

Which type of copper cable is the most common networking media?

Unshielded Twisted Pair (UTP) Signup and view all the answers

What is the purpose of the outer jacket in UTP cables?

To protect the copper wires from physical damage Signup and view all the answers

What is a characteristic of STP cables?

It has a foil shield for each pair of wires Signup and view all the answers

What is a method to mitigate attenuation in copper cables?

Strictly adhering to cable length limits Signup and view all the answers

What type of connector is used to terminate UTP and STP cables?

RJ-45 Signup and view all the answers

What is the primary purpose of the woven copper braid in a coaxial cable?

To act as a shield for the inner conductor Signup and view all the answers

What is the main method used by UTP cabling to limit crosstalk?

Cancellation of magnetic fields Signup and view all the answers

What is the organization responsible for establishing standards for UTP cabling?

TIA/EIA Signup and view all the answers

What is the primary purpose of the outer cable jacket in a coaxial cable?

To prevent minor physical damage Signup and view all the answers

What type of cable is commonly used in wireless installations?

Coaxial Signup and view all the answers

What is the purpose of twisting the wires in a UTP cable?

To prevent crosstalk amongst the wires Signup and view all the answers

What type of insulation is used in a coaxial cable?

Flexible plastic Signup and view all the answers

What is the primary function of the copper conductor in a coaxial cable?

To transmit electronic signals Signup and view all the answers

What is the primary function of a cable's shielding?

To prevent electromagnetic interference (EMI) Signup and view all the answers

What type of cable is ideal for scenarios where data needs to be transmitted over longer distances at higher bandwidth?

Fiber-optic cable Signup and view all the answers

What is the primary purpose of the TIA/EIA 568 standard?

To standardize element like cable types and cable length Signup and view all the answers

What type of cable is used for host-to-host connections?

Ethernet Crossover cable Signup and view all the answers

Which organization establishes electrical standards for copper cabling?

IEEE Signup and view all the answers

What is the main difference between a Straight-through cable and a Crossover cable?

The wiring pattern at each end Signup and view all the answers

What is the purpose of the Rollover cable?

To connect a host to a router or switch console port Signup and view all the answers

What is the rating of the cable that is used for high-speed networking applications?

Category 6 Signup and view all the answers

What is a key difference between single-mode fiber cables and multimode fiber cables?

The diameter of the core Signup and view all the answers

What is the maximum cable distance for multimode fiber?

550 meters Signup and view all the answers

What type of industry uses fiber-optic cabling for backbone cabling applications and interconnection infrastructure devices?

Enterprise Networks Signup and view all the answers

What is the purpose of the colored jacket on a fiber patch cord?

To identify the type of fiber Signup and view all the answers

What is a disadvantage of multimode fiber cables compared to single-mode fiber cables?

They have greater dispersion Signup and view all the answers

What is a common application of fiber-optic cabling?

Providing backbone cabling for high-traffic areas Signup and view all the answers

What is a characteristic of multimode fiber cables?

They use LEDs that transmit at different angles Signup and view all the answers

What is the primary use of fiber-optic cabling in enterprise networks?

For backbone cabling and interconnection infrastructure devices Signup and view all the answers

What is the primary purpose of the physical layer?

To provide a physical connection to a local network Signup and view all the answers

What is the capacity at which a medium can carry data?

Bandwidth Signup and view all the answers

What is the amount of time, including delays, for data to travel from one given point to another?

Latency Signup and view all the answers

What type of cabling is the most common type of cabling used in networks today?

Copper cabling Signup and view all the answers

What is the benefit of using copper cabling?

It has low resistance to electrical current flow Signup and view all the answers

What is the measure of usable data transferred over a given period of time?

Goodput Signup and view all the answers

What is the process by which the physical layer prepares data for transmission?

Encapsulation Signup and view all the answers

What is the function of a Network Interface Card (NIC)?

To connect a device to the network Signup and view all the answers

Study Notes

Limitations of Electrical Signals

Attenuation: electrical signals weaken over long distances
Interference: susceptible to electromagnetic interference (EMI) and radio frequency interference (RFI) from two sources
Crosstalk: interference between adjacent wires

Mitigation of Limitations

Strict adherence to cable length limits to mitigate attenuation
Metallic shielding and grounding in copper cables to mitigate EMI and RFI
Twisting circuit pair wires together to mitigate crosstalk

Types of Copper Cabling

Unshielded Twisted Pair (UTP):
- Most common networking media
- Terminated with RJ-45 connectors
- Interconnects hosts with intermediary network devices
- Key characteristics: outer jacket protects copper wires, twisted pairs protect signal from interference, color-coded plastic insulation electrically isolates wires
Shielded Twisted Pair (STP):
- Better noise protection than UTP
- More expensive and harder to install than UTP
- Terminated with RJ-45 connectors
- Interconnects hosts with intermediary network devices
- Key characteristics: outer jacket protects copper wires, braided or foil shield provides EMI/RFI protection, foil shield for each pair of wires provides EMI/RFI protection
Coaxial Cable:
- Consists of outer cable jacket, woven copper braid or metallic foil, flexible plastic insulation, and copper conductor
- Used in wireless installations and cable internet installations
- Commonly used with coaxial connectors

UTP Cabling

UTP has four pairs of color-coded copper wires twisted together and encased in a flexible plastic sheath
No shielding is used
Relies on cancellation and variation in twists per foot to limit crosstalk

UTP Cabling Standards and Connectors

Standards established by TIA/EIA (568) and IEEE
Cable types, cable length, connectors, cable termination, and testing methods standardized
Electrical standards rated by IEEE (Category 3, 5, 5e, 6)

Straight-through and Crossover UTP Cables

Straight-through: both ends T568A or T568B, used for host to network device connections
Crossover: one end T568A, other end T568B, used for host-to-host, switch-to-switch, and router-to-router connections

Fiber-Optic Cabling

Less common than UTP due to expense
Ideal for some networking scenarios
Transmits data over longer distances at higher bandwidth than copper cabling
Less susceptible to attenuation, and completely immune to EMI/RFI
Made of flexible, extremely thin strands of very pure glass
Uses laser or LED to encode bits as pulses of light

Physical Layer

Purpose: establish a physical connection to a local network
Connection can be wired or wireless
Applies to corporate offices and home networks
Network Interface Card (NIC) connects device to network
Not all physical connections offer the same level of performance
Transports bits across the network media

Bandwidth

Capacity of a medium to carry data
Digital bandwidth measures amount of data that can flow from one place to another in a given amount of time
Physical media properties, current technologies, and laws of physics play a role in determining available bandwidth

Bandwidth Terminology

Latency: amount of time, including delays, for data to travel from one point to another
Throughput: measure of transfer of bits across the media over a given period of time
Goodput: measure of usable data transferred over a given period of time

Characteristics of Copper Cabling

Copper cabling is the most common type of cabling used in networks today
Inexpensive, easy to install, and has low resistance to electrical current flow
Very small core

Fiber-Optic Cabling Usage

Fiber-optic cabling is used in four types of industry:
- Enterprise Networks
- Fiber-to-the-Home (FTTH)
- Long-Haul Networks
- Submarine cable Networks

Fiber-Optic Connectors

Fiber patch cords: used to connect fiber-optic cables
Yellow jacket for single-mode fiber cables and orange (or aqua) for multimode fiber cables

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Description

This quiz covers the limitations of electrical signals in computer networks, including attenuation and interference from sources like EMI, RFI, and crosstalk. Learn how to mitigate these effects to ensure reliable data transmission.