Explain Physical Topologies of LAN and WAN
Introduction
Physical topology describes how devices and cables are physically arranged in a network. It affects performance, cost, reliability, and scalability of LAN and WAN networks.
Problem Statement
Question:
Explain the physical topologies used in LAN and WAN networks in detail with advantages and disadvantages.
Answer
1. Physical Topologies in LAN
1) Bus Topology
Bus topology uses a single backbone cable to which all devices are connected. Data travels along this main cable and is received by all devices. It is simple and low cost but if the main cable fails, the entire network stops working.
| Advantages | Disadvantages |
|---|---|
| Easy to install | Backbone failure stops network |
| Low cost | Difficult troubleshooting |
| Uses less cable | Limited length |
2) Star Topology
In star topology, all devices are connected to a central hub or switch. Data passes through the central device before reaching the destination. It is easy to manage and expand, but if the central device fails, the whole network goes down.
| Advantages | Disadvantages |
|---|---|
| Easy to add/remove devices | Central device failure affects network |
| Easy fault detection | More cabling required |
| Reliable for small networks | Slightly costly |
3) Ring Topology
Ring topology connects devices in a circular form where each device is connected to two others. Data travels in one direction around the ring. It reduces data collision but failure of one device can affect the entire network.
| Advantages | Disadvantages |
|---|---|
| No data collision | One device failure stops network |
| Equal access | Hard to expand |
| Organized data flow | Maintenance is difficult |
4) Mesh Topology
In mesh topology, each device is connected to every other device. It provides multiple paths for data transmission. This topology is highly reliable but expensive and complex to install.
| Advantages | Disadvantages |
|---|---|
| Very reliable | Expensive |
| No single point of failure | Complex setup |
| High security | More cables required |
2. Physical Topologies in WAN
5) Point-to-Point Topology
Point-to-point topology connects two devices directly using a dedicated link. It is commonly used in WAN connections between two locations. It provides fast and secure communication but is not suitable for large networks.
| Advantages | Disadvantages |
|---|---|
| Simple configuration | Not scalable |
| Secure connection | Expensive for multiple links |
| High performance | Limited connection |
6) Hybrid Topology
Hybrid topology is a combination of two or more different topologies. It is used in large organizations for flexibility and scalability. Though efficient, it is complex and costly to design and maintain.
| Advantages | Disadvantages |
|---|---|
| Flexible | Complex design |
| Scalable | Higher cost |
| Suitable for large networks | Maintenance difficult |
Viva Questions with Answers
1. What is physical topology?
It is the physical layout of network devices and cables.
2. Which topology is most commonly used in LAN?
Star topology.
3. Which topology is most reliable?
Mesh topology.
4. What is the main drawback of bus topology?
If backbone fails, the network fails.
5. What is hybrid topology?
A combination of two or more network topologies.