This project demonstrates a basic Star Topology using a Network Hub in Cisco Packet Tracer. The objective is to visualize and understand how a Hub operates at Layer 1 (Physical Layer) of the OSI model, specifically its "blind" broadcasting behavior.
Cisco Packet Tracer 8.x
Networking Concepts: IPv4 Addressing, Star Topology, OSI Layer 1, ICMP (Ping).
The network consists of one Central Hub connected to four end devices using Copper Straight-Through cables:
PC0: 192.168.1.10
PC1: 192.168.1.11
PC2: 192.168.1.12
Laptop0: 192.168.1.13
Connectivity: Established physical links between PCs and the Hub.
Addressing: Configured static IPv4 addresses for all end devices.
Verification: Tested connectivity using the ping command in Simulation Mode.
Security/Efficiency Analysis: Observed the Hub's inability to filter traffic based on MAC or IP addresses.
During the simulation of an ICMP packet from PC0 to Laptop0, the following was observed:
Broadcasting: Instead of sending the packet directly to the destination (Laptop0), the Hub repeated the electrical signal out of every single port.
Security Risk: PC1 and PC2 received the packet even though it was not addressed to them. They only discarded it because the IP header did not match their own.
Collision Domain: All devices connected to the Hub share a single collision domain, which leads to network congestion as the number of devices grows.
Conclusion: This lab highlights why Hubs are obsolete in modern networks and have been replaced by Switches, which use a MAC address table to forward traffic intelligently.
Figure 1: Packet Tracer simulation showing the Hub broadcasting packets to all connected nodes. Hub Topology Screenshot
Download the .pkt file from the hub-topology.pkt
Open it in Cisco Packet Tracer.
Enter Simulation Mode.
Use the Add Simple PDU tool to send a packet from one PC to another and click Play to watch the broadcast behavior.