Physical Layer Flashcards
Physical Connection
*A physical connection is essential before network communication can occur.
*The connection can be wired or wireless depending on the network setup.
*Applies to both corporate offices and homes.
*Devices are connected through Network Interface Cards (NICs).
*NICs can be wired or wireless, and some devices may have multiple NICs.
*Performance levels vary among different physical connections.
Purpose of the Physical Layer
*The Physical Layer transports bits across the network media.
*It accepts frames from the Data Link Layer and encodes them as signals.
*This encoding process is the final step in encapsulation.
*The next device in the path receives the bits, re-encapsulates the frame, and makes routing decisions.
Physical Layer Characteristics
*Three main areas addressed by Physical Layer Standards: Physical Components, Encoding, Signaling.
*Physical Components include hardware devices, connectors, and cable materials.
*Encoding converts bits into a format recognizable by the next device.
*Signaling determines how bit values are represented on the physical medium.
Physical Layer Characteristics: Bandwidth
*Bandwidth measures the capacity of a medium to carry data.
*Digital bandwidth quantifies data flow in a given time.
*Physical media properties, technology, and physics influence available bandwidth.
*Units: bps, Kbps, Mbps, Gbps, Tbps.
*Bandwidth influences latency, throughput, and goodput.
Copper Cabling: Characteristics
*Common in networks; inexpensive, easy to install, low resistance.
*Limitations: Attenuation with distance, susceptibility to EMI/RFI and crosstalk.
*Mitigation: Adherence to cable length limits, shielding, twisted pair wiring.
UTP Cabling: Properties
*UTP has color-coded twisted pairs encased in plastic sheath.
*No shielding; relies on properties to limit crosstalk.
*Cancellation and variation in twists per foot mitigate crosstalk.
Fiber-Optic Cabling: Properties
*Ideal for high bandwidth and long-distance connections.
*Immune to EMI/RFI, less susceptible to attenuation.
*Made of thin glass strands, uses light pulses for data transmission.
*Single-Mode Fiber (SMF) for long distances, Multimode Fiber (MMF) for shorter distances.
Wireless Media: Limitations
*Carries electromagnetic signals using radio/microwave frequencies.
*Provides mobility but has limitations:
*Coverage area affected by location.
*Interference susceptibility.
*Security concerns due to open transmission.
*Shared medium reduces bandwidth with multiple users.
Wireless Standards
*IEEE and industry standards define wireless data communications.
*Specify encoding, transmission frequency, reception requirements, and more.
*Wi-Fi (802.11) for LAN, Bluetooth (802.15) for WPAN, WiMAX (802.16) for broadband access, Zigbee (802.15.4) for IoT.
Wireless LAN
*Wireless LAN (WLAN) components:
*Wireless Access Point (AP) concentrates wireless signals.
*Wireless NIC Adapters provide communication to network hosts.
*Stringent security measures needed to protect WLAN from unauthorized access and damage.
