Local Area Network (LAN)
A Local Area Network (LAN) is a network confined to a small geographical area, such as a home, office, or campus. It enables fast, reliable communication and resource sharing among devices.
๐น Key Characteristics of LAN
- Geographical Scope: Typically within 1 kmยฒ (building, floor, or campus).
- Ownership: Usually privately owned and managed.
- Data Transfer Speed: High โ typically 100 Mbps to 10 Gbps or more.
- Latency: Low, due to proximity of devices.
- Transmission Medium: Twisted pair cables, fiber optics, or wireless (Wi-Fi).
- Maintenance: Managed internally by network administrators.
๐น Functions of a LAN
- Sharing files, printers, and internet access.
- Centralized software and user management via servers.
- Facilitates local email and internal chat systems.
- Local hosting of web services and databases.
๐ผ๏ธ Textual Diagram โ Typical LAN Setup
+-----------+ +-----------+
| Laptop | | Printer |
+-----------+ +-----------+
\ /
\ /
+---------------------+
| Ethernet | โ Switch/Hub
+---------------------+
/ \
+-----------+ +-----------+
| Desktop 1 | | Desktop 2 |
+-----------+ +-----------+
|
+------------+
| Router |
+------------+
|
[Internet]
๐น Types of LAN
1. Wired LAN
- Uses physical cables (typically Ethernet).
- Offers high speed, low interference.
- Common in offices and server rooms.
2. Wireless LAN (WLAN)
- Uses radio waves (Wi-Fi).
- More flexible and mobile.
- Common in homes and cafes.
๐น LAN Protocols
| Protocol | Description |
|---|---|
| Ethernet (IEEE 802.3) | Most widely used wired LAN protocol. Uses CSMA/CD. |
| Wi-Fi (IEEE 802.11) | Wireless LAN standard. Uses CSMA/CA. |
| Token Ring (IEEE 802.5) | Older LAN protocol; now mostly obsolete. |
| MAC Addressing | Uniquely identifies devices at the Data Link Layer. |
๐น Advantages of LAN
- High Speed: Up to 10 Gbps with modern Ethernet.
- Low Cost: Infrastructure and maintenance are affordable.
- Security: Managed internally with firewalls, access control.
- Resource Sharing: Centralized access to printers, storage, and internet.
๐น Disadvantages of LAN
- Limited Range: Only suitable for small areas.
- Initial Setup Cost: Requires cabling, switches, routers.
- Maintenance: Needs network administration knowledge.
๐น Use Cases
- Educational Institutions: For connecting labs, classrooms, libraries.
- Businesses: Centralize data and applications on servers.
- Homes: Sharing internet, streaming, file transfers between devices.
๐น LAN Topologies
LANs can be implemented using different topologies:
| Topology | Description | Pros | Cons |
|---|---|---|---|
| Star | All nodes connect to a central hub/switch. | Easy to manage, scalable. | Hub failure = entire network down. |
| Bus | All devices share a single backbone. | Cheap, simple. | Traffic congestion, hard to troubleshoot. |
| Ring | Devices connected in a loop. | Predictable performance. | Failure in one device disrupts the loop. |
| Mesh | Each device connects to every other. | High reliability. | Expensive, complex. |
| Tree | Hierarchical, combines star and bus. | Scalable, structured. | Dependent on root node. |
๐น LAN vs WAN vs MAN
| Feature | LAN | MAN | WAN |
|---|---|---|---|
| Area Covered | Room/building | City or metro area | Country/global |
| Ownership | Private | Public or private | Public/ISP-managed |
| Speed | High | Medium | Lower (but improving) |
| Cost | Low | Medium | High |
| Technology | Ethernet, Wi-Fi | Fiber, Metro Ethernet | MPLS, Satellite, Fiber WAN |
๐น Summary
A LAN is the foundation of local digital connectivity, enabling devices within a limited area to communicate efficiently, share resources, and access external networks. It can be wired or wireless, and is the most commonly deployed network type in both homes and offices.
Next Up: WAN (Wide Area Network)