Star, Mesh, Bus, Ring, Hybrid

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Network Topologies

Network topology refers to the physical or logical arrangement of network devices and how they communicate. Each topology has advantages, disadvantages, and best-use cases.

We will cover:

1. Star Topology

2. Mesh Topology

3. Bus Topology

4. Ring Topology

5. Hybrid Topology

1. Star Topology

Definition

In a star topology, all devices are connected to a central device (hub, switch, or router). This central device manages communication between the devices.

Diagram

      PC1     PC2
        \     /
         [Switch]
        /     \
      PC3     PC4

How It Works

• Each device (PC, printer, server) connects directly to the switch.

• If PC1 wants to send data to PC3, the data first reaches the switch, which then forwards it to PC3.

Advantages

• Easy to troubleshoot – If one connection fails, only that device is affected.

• Scalable – Easy to add new devices without affecting the network.

• Efficient – Switches provide fast data transfer.

Disadvantages

• Single point of failure – If the switch fails, the entire network goes down.

• More expensive – Requires more cables and a central device (switch).

Practical Exercise

Task: Setting up a Star Topology in Packet Tracer

• Open Cisco Packet Tracer.

• Drag and drop a switch from the "Switches" category.

• Drag and drop four PCs from the "End Devices" category.

• Connect the PCs to the switch using straight-through Ethernet cables.

• Assign IP addresses:

  • PC1: 192.168.1.1

  • PC2: 192.168.1.2

  • PC3: 192.168.1.3

  • PC4: 192.168.1.4

• Test connectivity using the ping command in the CLI:

ping 192.168.1.2

If successful, it means the network is working.

2. Mesh Topology

Definition

In a mesh topology, each device is directly connected to every other device.

Diagram

   PC1 ----- PC2
   |  \     /  |
   |    \ /    |
   |    / \    |
   |  /     \  |
   PC3 ----- PC4

How It Works

• Data is sent through multiple paths.

• Full Mesh: Every device is connected to every other device.

• Partial Mesh: Some devices have multiple connections, but not all.

Advantages

• Redundant paths – If one connection fails, another path is available.

• High reliability – Used in critical applications (e.g., military, banking).

Disadvantages

• Expensive – Requires a lot of cables and ports.

• Complex setup – Hard to configure and manage.

3. Bus Topology

Definition

A bus topology has a single backbone cable to which all devices are connected.

Diagram

PC1 ---- PC2 ---- PC3 ---- PC4
           |
        Terminator

How It Works

• Data travels in both directions along the backbone.

• Each device listens for data and accepts packets addressed to it.

Advantages

• Easy to set up – Requires minimal cabling.

• Cost-effective – No need for expensive network devices.

Disadvantages

• Single point of failure – If the main cable (bus) fails, the entire network is down.

• Collisions – When two devices send data simultaneously, collisions occur, reducing efficiency.

4. Ring Topology

Definition

In a ring topology, each device is connected to exactly two other devices, forming a closed loop.

Diagram

   PC1 --- PC2
    |       |
   PC4 --- PC3

How It Works

• Data flows in one or both directions (Token Ring).

• A token is passed around; only the device holding the token can transmit data.

Advantages

• No collisions – Uses token passing to prevent data conflicts.

• Predictable performance – Each device gets a turn to send data.

Disadvantages

• Failure-sensitive – If one device or link fails, the network breaks (unless using dual rings).

• Hard to reconfigure – Adding or removing devices disrupts the network.

5. Hybrid Topology

Definition

A hybrid topology is a combination of two or more topologies (e.g., Star-Mesh, Bus-Ring).

Example: Star-Mesh Hybrid

• Star connects small groups of PCs.

• Mesh ensures redundancy between groups.

Diagram

       [Switch] ---- PC1
          |
       [Mesh Network]
      /     |     \
   PC2    PC3    PC4

Advantages

• Highly scalable – Can adapt to different network needs.

• Fault-tolerant – Uses redundancy from mesh networks.

Disadvantages

• Expensive – Requires multiple networking devices.

• Complex configuration – Needs expertise in managing different topologies.

Conclusion

Each topology has strengths and weaknesses. Here’s a quick summary:

Topology	Pros	Cons
Star	Easy to manage, scalable	Central device failure affects all
Mesh	Reliable, redundant	Expensive, complex setup
Bus	Cost-effective	Collisions, single point of failure
Ring	Predictable, no collisions	One failure breaks the network
Hybrid	Flexible, scalable	Expensive, complex

Keywords

Star Topology, Mesh Topology, Bus Topology, Ring Topology, Hybrid Topology, Network Architecture, Network Design, LAN Topology, WAN Topology, Network Infrastructure, Network Configuration, Packet Switching, Data Transmission, Network Redundancy, Network Scalability, Network Troubleshooting, Network Performance, Topology Advantages, Topology Disadvantages, Network Cabling, نتورک پلاس