Networking Basics

Access Point Components

• Access points include wireless antennas, Ethernet switchports, and an internet port
• Wireless antennas are often embedded inside the router version

Network Interface Cards (NICs)

• NICs connect devices to a network
• Ethernet NICs are for wired connections.
• Wireless LAN (WLAN) NICs are for wireless connections

OSI Physical Layer Function

• Provides the means to transport bits that form a data link layer frame across the network media

Open Systems Interconnection Model (OSI Model)

• It's a conceptual model that standardizes the communication functions of a telecommunication or computing system without regard to their underlying internal structure and technology.

Acronyms

• TCP stands for Transmission Control Protocol
• IETF stands for Internet Engineering Task Force
• ISO stands for International Organization for Standardization
• TIA stands for Telecommunications Industry Association
• EIA stands for Electronic Industries Association
• ITU stands for International Telecommunication Union
• ANSI stands for American National Standards Institute
• IEEE stands for Institute of Electrical and Electronics Engineers
• FCC stands for Federal Communication Commission
• ETSI stands for European Telecommunications Standards Institute
• CSA stands for Canadian Standards Association
• CENELEC stands for European Committee for Electrotechnical Standardization
• JSA/JIS stands for Japanese Standards Association
• EMI stands for Electromagnetic Interference
• RFI stands for Radio Frequency Interference

Physical Layer Standards

• Addresses electronic hardware devices (Physical Components)
• Addresses media and other connectors that transmit signals representing bits
• Encoding converts data bit streams into a predefined code
• Signaling generates electrical, optical, or wireless signals to represent 1s and 0s on media
• The way bits are represented is the signaling method

Bandwidth and Digital Bandwidth

• Bandwidth is the capacity at which a medium can carry data
• Digital bandwidth measures the amount of data flow from one place to another in a given timeframe

Factors Determining Network Bandwidth

• Properties of physical media
• Technologies chosen for signaling and detecting network signals

Bandwidth Units

• 1 bps is the fundamental unit
• 1 kbps equals 1,000 bps or 10^3 bps
• 1 mbps equals 1,000,000 bps or 10^6 bps
• 1 gbps equals 1,000,000,000 or 10^9 bps
• 1 tbps equals 1,000,000,000,000 or 10^12 bps

Bandwidth Terminology

• Latency measures the time for data to travel from one point to another, including delays
• Throughput measures the transfer of bits across media over time
• Goodput measures usable data transferred over time

Interference

• Electromagnetic interference (EMI) and Radio frequency interference (RFI) distort/corrupt data signals in copper media
• Crosstalk is a disturbance caused by electric/magnetic fields of a signal on one wire affecting the signal on an adjacent wire

Copper Cabling Types

• Unshielded twisted-pair (UTP) cabling is the most common networking media
• UTP cabling uses RJ-45 connectors for interconnecting hosts with intermediary devices like switches/routers
• Shielded twisted-pair (STP) offers better noise protection but is more expensive and harder to install than UTP
• STP also uses RJ-45 connectors
• STP shields against EMI/RFI and twists wires to counter crosstalk
• Coaxial cable has two conductors sharing the same axis

Coaxial Cable

• Still sees use in wireless and cable internet installations
• In wireless setups, coaxial cables connect antennas to devices, carrying RF energy
• Cable internet providers use it within customer premises, although fiber-optic cable replaces portions outside

UTP Cabling

• Consists of 4 pairs of color-coded copper wires twisted together and encased in a flexible plastic sheath

UTP Cable Categories

• Category 3 was for voice, then data transmission
• Category 5 supports 100Mbps, and 5e supports 1000 Mbps
• Category 6 has a separator for higher speeds, supporting up to 10 Gbps
• Category 7 supports 10 Gbps
• Category 8 supports 40 Gbps

Main Cable Types by Wiring

• Ethernet straight-through cables are common for connecting a host to a switch or a switch to a router
• Ethernet crossover cables connect similar devices like switch-to-switch or host-to-host, but are considered legacy
• NICs now use auto-MDIX to detect cable type automatically. Rollover cables connect a workstation to a router or switch console port

Fiber-Optic Cables

• Single-mode fiber (SMF) uses a small core and laser tech for single light ray transmission over hundreds of kilometers
• Multimode fiber (MMF) uses a larger core and LEDs for light pulses, common in LANs with bandwidth up to 10 Gbps over links up to 550 meters

Fiber-Optic Cabling Use Cases

• Enterprise networks use fiber-optic cabling for backbone cabling and interconnecting infrastructure devices
• Fiber-to-the-Home (FTTH) provides broadband to homes and small businesses
• Long-haul networks connect countries and cities
• Submarine cable networks provide reliable, high-speed solutions over transoceanic distances

Fiber-Optic Connector Type

• Straight-Tip ST connectors were early types with a twist-on/twist-off mechanism
• Subscriber Connector SC are 'square' or 'standard' connectors, widely used in LANs/WANs, with a push-pull insertion
• Lucent Connector LC simplex connectors are smaller versions of SC connectors, called "little" or "local" connectors
• Duplex multimode LC connector is similar to an LC simplex connector, but uses a duplex connector

Fiber Patch Cords

• SC-SC Multimode Patch Cord
• LC-LC Single-Mode Patch Cord
• ST-LC Multimode Patch Cord
• SC-ST Single-Mode Patch Cord

Wireless Limitations

• Effective coverage can be limited by construction materials and terrain
• Susceptible to disruption from devices like phones, lights, and microwaves
• Wireless communication requires no physical media access, making it less secure

Wireless LANs

• Operate in half-duplex
• Many users reduce bandwidth for each user

Wireless Standards

• Wi-Fi (IEEE 802.11) is WLAN tech using CSMA/CA, requiring wireless NICs to listen before transmitting

Bluetooth

• Bluetooth (IEEE 802.15) is a WPAN standard using device pairing to communicate up to 1 to 100 meters

WiMAX

• WiMAX (IEEE 802.16) is for Worldwide Interoperability for Microwave Access, uses point-to-multipoint for wireless broadband

Zigbee

• Zigbee (IEEE 802.15.4) is for low-data rate, low-power with short range, typically for IoT applications

Common Wireless LAN Devices

• Wireless access points (APs) concentrate wireless signals and connect to wired infrastructure
• Wireless NIC adapters provide wireless communication for network hosts