Multi-Router Network Simulation with OSPF and DHCP in GNS3 This project presents a multi-router IPv4 network designed and tested in GNS3. The work covers dynamic routing with OSPF, automatic IP address assignment with DHCP, VLAN-based switching, end-to-end ICMP testing, and packet-level verification using Wireshark. Network topology The main topology contains multiple routers, Ethernet switches, and VPCS hosts connected across several /24 IPv4 subnets. OSPF is used to exchange routes automatically between the routed networks. A separate Layer 2 topology was also created to test VLAN segmentation across multiple switches. Six hosts are assigned to VLANs 10, 20, and 30, with the same VLANs distributed across different switches. OSPF routing OSPF was configured between the routers so that remote LANs could be reached without manually defining static routes for every destination. Cisco IOS routing tables were used to verify directly connected and dynamically learned OSPF routes. Connectivity and packet analysis End-to-end communication was tested using ICMP echo requests between hosts located on different subnets. Wireshark captures were used to inspect both ICMP traffic and OSPF control packets, including OSPF Hello messages sent to 224.0.0.5. This confirms both data-plane connectivity and control-plane operation. DHCP configuration DHCP pools were configured on selected routers to assign IPv4 addresses and default gateways automatically to VPCS clients. The configuration was verified using client-side address acquisition, DHCP binding tables, pool information, and server statistics. Tools and technologies GNS3 · Cisco IOS · OSPF · DHCP · IPv4 · VLANs · Wireshark · ICMP · VPCS Note The GNS3 project file contains the topology and node definitions. The Cisco IOS image used by the project is not included in this repository.