EIGRP vs OSPF — Differences, Metrics, Convergence and Which to Choose
EIGRP uses DUAL with feasible successors for near-instant failover; OSPF uses Dijkstra with a full link-state map and…
A network is two or more devices connected so they can exchange data and share resources. That is the whole definition, the rest is detail about scale, medium and purpose. Two laptops joined by one cable are a network. So is the internet.
What makes a network useful is not the wire, it is the agreement: every device follows the same set of rules (protocols) about how to address, package and acknowledge data. Without that agreement you have devices in the same room, not a network.
Network vs Networking, the Difference
People use these interchangeably and they are not the same:
- Network, the noun. The interconnected set of devices itself.
- Networking, the verb. The practice of designing, building, configuring and maintaining that set of devices.
Types of Networks
Networks are classified mainly by geographic scope, and secondarily by purpose.
| Type | Full name | Typical reach | Where you see it |
|---|---|---|---|
| PAN | Personal Area Network | A few metres | Bluetooth earbuds, smartwatch, wireless keyboard |
| LAN | Local Area Network | One building or floor | Home network, office, school computer lab |
| WLAN | Wireless LAN | Same as a LAN | Wi-Fi. It is a LAN, just over radio instead of copper |
| CAN | Campus Area Network | A cluster of buildings | University campus, hospital complex, industrial park |
| MAN | Metropolitan Area Network | A city | Municipal fibre rings, cable ISP distribution networks |
| WAN | Wide Area Network | Countries or continents | Corporate branch connectivity; the internet is the largest WAN |
| SAN | Storage Area Network | Data centre | Block-level storage over Fibre Channel or iSCSI |
| VPN | Virtual Private Network | Logical, not physical | An encrypted tunnel that makes a remote device behave as if it were on the LAN |
One common mix-up: a WLAN is not a separate category from a LAN. It is a LAN whose access layer happens to be wireless. Almost every home network is both, Wi-Fi devices and Ethernet devices sharing one broadcast domain behind the same router.
Components of a Network
| Component | OSI layer | What it does |
|---|---|---|
| NIC (Network Interface Card) | 1–2 | Gives a device its physical port and its MAC address. Every networked device has one, wired or wireless. |
| Hub | 1 | Repeats every incoming signal out of every other port. No intelligence, no MAC learning. Effectively obsolete. |
| Switch | 2 | Learns which MAC address lives on which port and forwards frames only where they need to go. The backbone of every modern LAN. |
| Router | 3 | Connects different networks and forwards packets between them using IP addresses. Your home router also does NAT, DHCP and firewalling. |
| Access Point | 1–2 | Bridges Wi-Fi clients onto the wired LAN. In business networks it has a wired uplink; in a home router it is built into the same box. |
| Modem | 1 | Converts the ISP’s signal (DSL, cable, fibre) into Ethernet the router can use. They are long-lived but not permanent, see how long modems last, and the guides to the best modems for Cox and router-modem combos for Xfinity when it is time to replace one. |
| Firewall | 3–7 | Enforces which traffic is allowed between network zones. |
| Server | — | A host that provides a service, files, DNS, DHCP, web, email, to other hosts. |
| Cabling | 1 | Twisted pair (Cat5e/6/6a), fibre optic, or coax. Fibre for distance and immunity to interference; copper for everything else. |
A typical home network uses exactly three of these: a modem, a combined router/switch/AP, and NICs in each device. An enterprise network separates them into dedicated boxes so each can be scaled independently.
Hub vs Switch vs Router, the Distinction That Matters Most
These three get confused constantly, and the difference is not size or port count:
- A hub repeats a signal blindly to every port. Everyone hears everything, and two devices talking at once causes a collision. An Ethernet splitter is cruder still, it is not a network device at all.
- A switch reads the destination MAC address and forwards the frame to that one port. Each port is its own collision domain.
- A router reads the destination IP address and moves the packet between separate networks. It also stops broadcasts, which a switch does not.
The full breakdown, with the myths corrected, is in Hub vs Switch vs Router.
Network Topologies
Topology is the arrangement of the connections, the shape of the network.
| Topology | Layout | Strength | Weakness | Still used? |
|---|---|---|---|---|
| Bus | All devices tap one shared cable | Cheap, minimal cabling | One cable break kills the whole segment; shared bandwidth; hard to fault-find | Legacy only |
| Star | Every device has its own cable to a central switch | One failed cable affects one device; easy to troubleshoot and extend | The central switch is a single point of failure | Yes, the standard |
| Ring | Each device connects to two neighbours in a loop | Predictable, no collisions with token passing | A single break splits the ring unless it is dual-ring | Rare; survives in some metro fibre rings |
| Mesh | Many redundant paths between nodes | Extremely resilient, traffic reroutes around failures | Cabling and configuration cost grows fast | Yes, WAN cores, wireless mesh, data centre fabrics |
| Tree / Hierarchical | Stars linked into layers (access, distribution, core) | Scales cleanly to thousands of ports | An upper-layer failure isolates everything below it | Yes, the enterprise standard |
In practice, nearly every modern network is a tree of stars: switches in a star at the access layer, uplinked into a hierarchy, often with a mesh between core devices for redundancy.
Protocols, the Rules Devices Agree On
- Ethernet (IEEE 802.3), how frames are formatted and moved over wire. Layer 2.
- Wi-Fi (IEEE 802.11), the same job over radio.
- TCP/IP, the suite the internet runs on. IP handles addressing and routing; TCP or UDP handles delivery. The pairing of an address and a port is what forms a socket.
- DHCP, hands out IP addresses automatically so you do not configure each device by hand.
- DNS, translates names into IP addresses.
- ARP, maps an IP address to the MAC address on the local segment, caching the result in the ARP table.
The OSI model is the framework that organises all of these into seven layers, and it is worth learning early, most troubleshooting is really the question “which layer is broken?”
Why Networks Exist, the Real Benefits
- Resource sharing. One printer, one storage array, one internet connection serving many devices instead of one each.
- Centralised data. One authoritative copy of a file, backed up once, rather than divergent copies on every machine.
- Communication. Email, VoIP, video conferencing and messaging all depend on the network layer beneath them.
- Central management. Software deployment, patching, access control and monitoring can be done from one place instead of desk by desk.
- Cost. Sharing infrastructure is cheaper per user than duplicating it, and that gap widens with scale.
Securing a Network
A network that connects everything also exposes everything, so security is not a bolt-on. The basics:
- Firewalls control which traffic crosses between zones, internet, internal LAN, guest, servers.
- Segmentation with VLANs limits how far an intruder can move if one device is compromised.
- Encryption (WPA3 on Wi-Fi, TLS for web traffic, IPsec for site-to-site links) protects data in transit.
- Intrusion detection flags traffic patterns that match known attacks.
- Access control, 802.1X, strong credentials, and least-privilege rules on who reaches what.
Our network security guide covers each of these properly.
Basic Network Troubleshooting
Work bottom-up through the layers, it is faster than guessing:
- Physical. Is the cable in? Are the link lights on? Swap the cable before you suspect anything cleverer.
- Addressing. Run
ipconfig(Windows) orip addr(Linux). A 169.254.x.x address means DHCP failed. - Local reachability.
pingyour default gateway. Failure here means the problem is on your own LAN. - Internet reachability.
ping 8.8.8.8. If that works but names do not resolve, it is DNS. - Path. tracert / traceroute shows where the path breaks or where latency jumps.
The full command list is in network troubleshooting commands.
Frequently Asked Questions
What is the simplest possible network?
Two devices connected directly by a single cable, each with an IP address in the same subnet. No switch or router required.
Is Wi-Fi a different type of network from a LAN?
No. Wi-Fi is the wireless access method for a LAN. A WLAN and a wired LAN can be, and usually are, the same network.
What is the difference between a LAN and a WAN?
Scope and ownership. A LAN covers one site and you own all of it. A WAN links sites across distance and normally rides on circuits leased from a service provider.
Do I need a switch if I already have a router?
A home router already contains a small switch, that is what the four LAN ports are. You add a separate switch only when you need more ports or want managed features such as VLANs and PoE.
What is the difference between a network and the internet?
The internet is a network, specifically, a global interconnection of millions of independently operated networks that agree to route to each other using BGP.
