Designed a redundant switched network with VLAN segmentation, trunking, and STP, then configured two routed networks and analyzed frame changes across a switch vs router using Packet Tracer simulation and PDU inspection.
Overview
This project demonstrates the design and implementation of a switched enterprise network with VLAN-based traffic segmentation, redundancy, and Layer 3 packet forwarding analysis using Cisco Packet Tracer.
The objective was to replace legacy hubs with switches to reduce collisions, improve resiliency through redundant links, and isolate departmental traffic for security purposes. The project also examines how packets are handled differently at Layer 2 (switching) versus Layer 3 (routing) by observing frame transformations as traffic traverses a router.
The work emphasizes network performance, security segmentation, and protocol behavior, combining VLAN configuration, trunking, Spanning Tree Protocol (STP), IP addressing, dynamic routing, and packet inspection.
Scope & Objectives
Design a switched network for a multi-floor building with multiple departments
Replace hubs with switches to eliminate collisions and improve network stability
Implement VLAN-based segmentation for departmental traffic isolation
Configure trunk links and allow only required VLANs across the backbone
Provide redundancy and failover using Spanning Tree Protocol (STP)
Configure Layer 3 addressing and routing between separate networks
Observe and analyze frame behavior as packets traverse switches and routers
Platform & Technology Platform
Cisco Packet Tracer
Technologies & Concepts
Layer 2 switching and MAC address learning
VLAN configuration and access port assignment
802.1Q trunking
Spanning Tree Protocol (STP) for loop prevention and redundancy
IPv4 addressing (Class A and Class C private networks)
Layer 3 routing and default gateway configuration
RIP version 2 (RIPv2) dynamic routing
ICMP connectivity testing
Frame and packet inspection using PDU simulation
Part 1: Switched Network Design
Key Observations
Replacing hubs with switches eliminated collision-related performance issues by separating collision domains at each switch port.
VLAN segmentation successfully isolated departmental traffic, preventing unauthorized communication between Marketing, Sales, and Administration networks.
Trunk links enabled multiple VLANs to traverse a single backbone connection while maintaining logical separation of traffic.
Spanning Tree Protocol (STP) effectively prevented Layer 2 loops and ensured continued connectivity by activating alternate paths during link failures.
Centralizing servers within a dedicated VLAN allowed controlled access while simplifying network management and security enforcement.
Part 2: Layer 3 Configuration and Packet Switching
Implementation Summary
Configured two private IPv4 networks (Class A and Class C) connected via a router
Assigned IP addresses, subnet masks, and default gateways to end hosts and router interfaces
Verified end-to-end connectivity using ICMP (ping) testing
Used Packet Tracer’s PDU simulation to observe frame behavior across switches and routers
Key Observations
IP addresses remain unchanged end-to-end during packet delivery
MAC addresses remain unchanged when frames pass through a switch
MAC addresses are rewritten when frames pass through a router
Routers forward traffic based on Layer 3 (IP) information, while switches forward traffic based on Layer 2 (MAC) information