This topic covers the basics of data networks, including the purpose of networks, types of networks (LAN, WAN, MAN), network components (routers, switches, hubs), and the OSI model.
Introduction to Data Networks – Study Notes
| Aspect | Description |
|---|---|
| Definition | A collection of interconnected devices (computers, servers, routers, switches, etc.) that exchange digital information using communication protocols. |
| Purpose | Enable sharing of resources (files, printers, applications), support communication (email, messaging, video), and provide access to services (cloud, Internet). |
| Key Characteristics | • Packet‑oriented transmission • Logical addressing (IP) • Layered architecture (OSI/TCP‑IP) • Scalable and fault‑tolerant |
| Component | Role |
|---|---|
| End Devices | Sources or destinations of data (PCs, smartphones, IoT sensors). |
| Transmission Media | Physical path for bits – copper (twisted‑pair, coax), fiber‑optic, wireless (radio, microwave, satellite). |
| Network Interface Card (NIC) | Provides electrical/optical conversion and MAC addressing. |
| Switches | Forward frames within a LAN based on MAC addresses; create separate collision domains. |
| Routers | Connect multiple networks; forward packets using IP addresses; perform routing decisions. |
| Access Points (APs) | Bridge wired LANs to wireless clients (Wi‑Fi). |
| Firewalls / Security Appliances | Inspect and filter traffic according to security policies. |
| Servers | Host applications, files, DNS, DHCP, authentication, etc. |
| Topology | Description | Typical Use |
|---|---|---|
| Bus | All nodes share a single communication line. | Legacy Ethernet (10BASE‑2/5). |
| Star | Devices connect to a central hub/switch. | Modern Ethernet LANs. |
| Ring | Nodes connected in a closed loop; token passing. | Token Ring, some Metro Ethernet. |
| Mesh | Redundant interconnections; each node may have multiple paths. | WAN backbones, data‑center fabrics. |
| Hybrid | Combination of two or more basic topologies. | Campus networks, large enterprises. |
| TCP/IP Layer | OSI Equivalent(s) | Core Functions |
|---|---|---|
| Link | Physical + Data Link | NIC, MAC, Ethernet, Wi‑Fi. |
| Internet | Network | IP addressing, routing, ICMP. |
| Transport | Transport | TCP (reliable), UDP (unreliable). |
| Application | Session + Presentation + Application | HTTP, FTP, DNS, SSH, etc. |
| Concept | Details |
|---|---|
| MAC Address |