What are Local Area Networks – LANs?
A Local Area Network (LAN) is an individual computer network that covers a single geographical area, providing networking services and applications to people within a common managerial structure, such as a single business, campus, or region.
A LAN is usually administered by a single organization. The administrative control that governs the security and access control policies is enforced on the network level.
LANs and WANs are very useful to individual organizations. They connect the users within the organization. They allow many forms of communication including exchanging of e-mails, corporate training, and other resource sharing.
Simplified Definition:
A LAN interconnects computers, servers, printers, and other devices in a circumscribed location.It allows these devices to communicate with each other using protocols like TCP/IP over Ethernet or Wi-Fi. LANs are typically exclusive to an organization, such as a school, office, association, or church.
Characteristics:
Physical Proximity: LANs cover a small geographic area, such as a single building or campus.
High Data Transfer Rates: Devices within a LAN can communicate at high speeds due to their close proximity.
Shared Resources: LANs enable devices to share resources like files, printers, and internet connections.
Managed by an Organization: LANs are usually owned and maintained by the organization that operates within the area.
Types of LANs:
Wired LANs: These use physical cables (such as Ethernet) to connect devices. Common examples include office networks with wired desktop computers.
Wireless LANs (Wi-Fi): These rely on wireless signals for communication. Wi-Fi networks are prevalent in homes, coffee shops, and public spaces.
Virtual LANs (VLANs): VLANs logically group network nodes, allowing segmentation without major infrastructure changes. For instance, different departments in an office can share the same switch but behave as separate networks.
LAN Architectures:
Client-Server LANs: In this architecture, several devices (clients) connect to a central server. The server manages file storage, application access, and network traffic.
Peer-to-Peer LANs: In a peer-to-peer setup, devices communicate directly with each other without a central server. This is common in small home networks.
Benefits of LANs:
Resource Sharing: Devices can share files, printers, and internet access.
Centralized Management: Servers facilitate efficient management of network resources.
Fast Communication: High-speed communication within the LAN.
Security: LANs can be secured using firewalls, access controls, and encryption.
LAN Topologies.
Local Area Network (LAN) topologies describe the arrangement of devices and connections within a limited geographical area. Let’s explore some common LAN topologies:
Bus Topology:
Description: In a bus topology, every device is connected to a single cable that runs from one end of the network to the other.
Pros:
i. Easy installation.
ii. Requires fewer cables than mesh or star topologies.
iii. Cost-effective for small businesses.
Cons:
i. Single point of failure (if the main cable breaks, the entire network is affected).
ii. Efficiency decreases rapidly with each added node.
iii. Data can only travel in one direction at any point in time.
Usage: Bus topologies were common in smaller networks but are now outdated due to limitations and congestion issues.
Star Topology:
Description: In a star topology, all devices connect to a central hub or switch. The hub acts as a central point for communication.
Pros:
i. Easy to manage and expand.
ii. Fault tolerance (failure of one device doesn’t affect the entire network).
iii. High performance.
Cons:
i. If the hub fails, the entire network is affected.
ii. Requires more cabling than bus topology.
Usage: Commonly used in modern LANs due to its scalability and reliability.
Ring Topology:
Description: Devices are connected in a circular loop, where data travels in one direction around the ring.
Pros:
i. Simple layout.
ii. No collisions (only one device can transmit at a time).
Cons:
i. Single point of failure (if any device or cable breaks, the entire network is disrupted).
ii. Limited scalability.
Usage: Rarely used today due to its limitations.
Tree Topology:
Description: Combines features of bus and star topologies. Multiple star topologies are interconnected through a central bus.
Pros:
i. Scalable and flexible.
ii. Fault tolerance.
iii. Suitable for larger networks.
Cons:
i. Complex to set up and manage.
ii. More expensive due to additional cabling.
Usage: Common in larger LANs where hierarchical organization is needed.
Mesh Topology:
Description: Every device is directly connected to every other device. Full redundancy ensures fault tolerance. Read Spanning Tree Protocol
Pros:
i. High reliability (no single point of failure).
ii. Efficient communication.
Cons:
i. Expensive (requires many connections).
ii. Complex to set up.
Usage: Used in critical applications (e.g., stock exchanges, data centers) where reliability is paramount.
Remember that each topology has its own compromises, and organizations choose based on their specific needs and design goals. Whether it’s a simple star network or a complex mesh, LAN topologies play a crucial role in connecting devices within a confined area.
What is the difference between LAN and WAN?
The common key differences between Local Area Networks (LANs) and Wide Area Networks (WANs):
Coverage:
LAN: A LAN covers a small geographic area, such as a home, office, school, or group of buildings. It’s designed for localized networking within a limited space.
WAN: In contrast, a WAN spans larger geographical areas, including cities, states, and even nations. WANs connect multiple LANs across long distances.
Speed and Data Transfer Rates:
LANs tend to be faster because they cover shorter distances and use dedicated connections. Typical LAN speeds can reach up to 1000 Mbps.
WANs have lower data transfer rates compared to LANs. They operate at speeds around 150 Mbps or less.
Technology:
LANs primarily use connectivity technologies like Ethernet and Token Ring.
WANs employ technologies such as MPLS, ATM, Frame Relay, and X.25 for longer-distance communication.
Connection:
LANs can be connected to other LANs over any distance via telephone lines and radio waves.
WANs connect computers through public networks (like the Internet), leased lines, or satellites.
LAN Components:
LANs use Layer 2 devices like switches and bridges.
WANs involve Layer 3 devices such as routers, multi-layer switches, and technology-specific devices like ATM or Frame Relay switches.
LAN Fault Tolerance:
LANs tend to have fewer problems due to their smaller scale.
WANs are less fault-tolerant because they consist of a larger number of interconnected systems.
Data Transmission Error:
LANs experience fewer data transmission errors.
WANs encounter more data transmission errors compared to LANs.
Set-Up Costs:
Expanding a LAN with a few extra devices is not very expensive.
WANs involve more complex infrastructure and may require higher set-up costs.
In summary, while LANs provide localized connectivity within smaller areas, WANs enable widespread communication across large distances. Whether you’re sharing files within an office LAN or accessing websites on the global WAN (like the Internet), both play crucial roles in their area of use.
Communication with data, voice, and video is critical to business survival. As a result, a properly designed LAN is a fundamental requirement for doing business today. You must be able to recognize a well-designed LAN and select the appropriate devices to support the network specifications of a small- or medium-sized business.
How To Set Up a Home LAN
The Internet – A Network of Networks
Cabling Network Devices
Straight Through Cables
Cross Over Cables
