🛠️ Tool Used
The tool CISCO Packet Tracer (CPT) is what I used to form an ISP-handed network of three topologies:
- Bus topology
- Tree topology
- Star topology
Together, they form a hybrid topology.
🎯 Purpose
The idea of making such a simulation of an ISP network was to strengthen my knowledge and skills required to configure and study:
- Real-world topologies
- Routing methods & protocols
- ISP systems
🗺️ Design Overview
- A core router is used to connect to 3 routers, each representing one of the three topologies.
- Routing from one LAN (topology) to another happens through routers.
- This required an appropriate use of a routing algorithm such as OSPF.
🤔 Why I Used OSPF?
- OSPF stands for Open Shortest Path First.
- It’s an Internal Gateway Protocol (IGP) used for routing within a single autonomous system.
- Routing could also be done manually (static routes), but that approach is not scalable or efficient.
- OSPF provided automation, scalability, and a well-defined configuration method.
Router> enable
Router# configure terminal
Router(config)# router ospf 1
Router(config-router)# network 10.0.0.0 0.0.0.255 area 0
Router(config-router)# network 192.168.1.0 0.0.0.255 area 0
Router(config-router)# end
Router# show ip ospf neighbor
🌍 Simulating the Internet
- The ISP data center can be expanded with servers, DNS servers (cache servers), and other devices.
- In reality, the internet is a network of ISPs connected together.
- To simulate this, I added another router (Global Router) to represent the internet connection with the ISP.
📚 What I Learned
Designing and configuring this project felt like engineering a small-scale ISP.
I learned about:
- Routing protocols (like OSPF)
- Routers’ ability to store and use neighboring routers’ addresses for routing
- DHCP usage for handling private/topological devices
Router(config)# ip dhcp excluded-address 192.168.1.1 192.168.1.10
Router(config)# ip dhcp pool LAN_POOL
Router(dhcp-config)# network 192.168.1.0 255.255.255.0
Router(dhcp-config)# default-router 192.168.1.1
Router(dhcp-config)# dns-server 8.8.8.8
Router(dhcp-config)# exit
- DNS servers for routing HTTP requests to web servers placed on the “global internet” (simulated search engines, since Packet Tracer doesn’t support real web apps/frameworks)
đź’ Final Thoughts
This was a great learning experience — a foundational design and configuration setup for me to explore more complex systems and simulations in Computer Communications & Networking.
🤝 Over to You
Have you ever built a network simulation in Packet Tracer or GNS3?
Which routing protocols did you use — OSPF, RIP, BGP?
Share your experience in the comments 👇
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