Physical Layer (Layer 1) – Complete Devices & Services
Network Card (NIC)
Ethernet or Wi-Fi adapter inside PC/laptop/phone.
Ethernet Cables (Cat5e/6/6A/7/8)
Most common wired network cables with RJ45 plugs.
Fiber Optic Cables (SM/MM)
Glass cables carrying light – used for very long & fast links.
Repeater
Amplifies weak signals to go farther (rare today).
Hub (Dumb Hub)
Old multi-port repeater – sends data to everyone.
Patch Panel
Wall of organized cable sockets in server rooms.
Media Converter
Converts copper ↔ fiber or different speeds.
Transceiver (SFP/SFP+/QSFP)
Small pluggable modules for fiber or copper.
Network Access Controller
Physical appliance that enforces who joins the network.
Biometric Scanner
Fingerprint/face/iris readers with Ethernet port.
Electric Door Strike/Lock
Physical lock controlled by access system.
RFID / Proximity Card Reader
Tap-card readers (125kHz/13.56MHz) on doors.
PoE Injector / Midspan
Adds power to Ethernet cable for cameras/IP phones.
ONT (Optical Network Terminal)
Box that converts fiber from ISP to Ethernet.
Wi-Fi 6 / 6E / 7
Latest wireless standards using 2.4/5/6 GHz bands.
5G Cellular
Mobile broadband using radio towers.
GPON / XGS-PON
Fiber-to-the-home technology (1–10 Gbps).
Wiegand / RS-485 Controller
Old-school access control wiring standard.
Coaxial Cable Modem
Converts cable TV signal to Ethernet.
Antenna (Wi-Fi / 4G/5G)
Physical radio transmitter/receiver.
Bluetooth 5.3
Short-range wireless for earbuds, keyboards.
PLC (Powerline Adapter)
Sends internet through electrical wiring.
DAC Cable (Direct Attach)
Short fixed copper/fiber cable for racks.