Transmission media and network software: twisted pair, coax, fibre, wireless, client and server software
In short: Transmission media carry the signal: copper twisted pair (most LANs), coaxial cable (older networks and cable TV), fibre optic (long distances and high speed) and wireless (radio, microwave, satellite, infrared). Network software lets users and administrators use and manage the network.
What are transmission media?
The transmission medium is whatever physically carries the signal between devices. It is either guided (a cable: copper or glass) or unguided (wireless: radio, microwave, infrared).
Twisted-pair cable
Pairs of insulated copper wires are twisted around each other inside a plastic jacket. The twisting cancels much of the electrical interference (noise) from nearby cables and equipment. It is inexpensive, flexible and the standard for LANs and telephone lines, using the RJ-45 connector for Ethernet.
| UTP (unshielded) | STP (shielded) | |
|---|---|---|
| Shielding | None; relies on twisting | Foil or braid around pairs |
| Interference resistance | Good | Better, for noisy environments |
| Cost and handling | Cheaper, thinner, easier to install | More expensive, stiffer, must be grounded |
| Typical use | Offices and homes | Factories, near heavy electrical equipment |
Common categories: Cat 5e (1 Gb/s), Cat 6 (1 Gb/s, 10 Gb/s over short runs) and Cat 6A (10 Gb/s up to 100 m). The maximum Ethernet copper run is 100 metres.
Coaxial cable
A single copper conductor surrounded by insulation, a metal shield and an outer jacket. It was once the most common network cable because it was cheap, light and easy to install: Thinnet (10BASE2) reached 185 m and Thicknet (10BASE5) reached 500 m, using BNC connectors. It is no longer used for LANs but is still common for cable TV, cable broadband and CCTV.
Fibre-optic cable
A thin glass core surrounded by cladding and protective layers carries light instead of electricity. That makes it immune to electrical interference, very hard to tap, and able to carry far more data over far longer distances than copper.
- Multimode fibre: wider core, cheaper light sources, distances up to a few hundred metres to around 2 km. Used inside buildings and campuses.
- Single-mode fibre: very thin core, laser light, distances of tens of kilometres or more. Used between buildings, by ISPs and under the sea.
Wireless media
- Radio (Wi-Fi, Bluetooth): short-range wireless LANs and PANs.
- Microwave: high-frequency radio beams between dishes in line of sight, used to link buildings or towers.
- Satellite: satellites receive signals, amplify them and send them back down to another location, reaching remote areas, ships and aircraft.
- Cellular (4G/5G): towers each cover an area (a cell) and hand devices over as they move.
- Infrared: short-range light links needing line of sight, such as TV remotes.
Networking software
Hardware moves the bits, but software makes the network usable and manageable. Network software lets users reach shared resources easily, lets administrators add or remove users, protects the network against unauthorised access and attacks, and makes network virtualisation possible.
- Client software runs on the user's device and uses a service provided by a server, for example an email app, a web browser or a VPN client.
- Server software runs on servers and provides services to many clients, for example a server operating system, web server, email server or database server.
- Management software monitors and configures the network, for example controllers, monitoring systems and configuration tools.
Practice
Why is fibre used between buildings instead of copper?
What is the maximum length of a copper Ethernet run?
When would you choose STP instead of UTP?
Key takeaways
- Media are guided (copper, fibre) or unguided (wireless).
- Twisted pair with RJ-45 is the LAN standard; copper runs are limited to 100 m.
- Coax is legacy for LANs but still used for cable TV and CCTV.
- Fibre carries light: multimode for short runs, single-mode for long distances.
- Client, server and management software make the network usable and secure.
Original content written by Mohamed Fayas for FM TecHub. © 2026 FM TecHub. You're welcome to share a link to this page; please don't copy the text elsewhere without permission.