Designed and configured a 3-router enterprise WAN topology using EIGRP dynamic routing — demonstrating automatic route advertisement, neighbour adjacency formation, and full network convergence across 5 subnets with zero static routes.
In the previous Static Routing project, every route had to be manually entered on every router. EIGRP eliminates that entirely — routers automatically discover neighbours, share their routing tables, and recalculate paths if a link goes down. This project proves that concept works in practice.
The network uses EIGRP Process 2 across all three routers. Once network statements are declared, EIGRP does the rest — forming adjacencies, flooding topology updates, and converging on optimal paths using the DUAL algorithm.
The complete EIGRP network topology built in Cisco Packet Tracer 8.2. Three Cisco ISR4331 routers (R1, R2, R3) are interconnected via Serial WAN links forming a hub-and-spoke design. R2 sits at the centre connecting to both R1 (via Serial0/1/0) and R3 (via Serial0/1/1). Three Cisco 2960-24TT switches (Switch0, Switch1, Switch2) provide LAN distribution. All links show green confirming full convergence.
R1 (ISR4331) is configured as the left-site router. GigabitEthernet0/0/0 is assigned 192.168.1.1/24 as the LAN interface connecting Switch0 and its end devices. Serial0/1/0 is assigned 192.168.2.1/24 as the WAN uplink to R2. EIGRP Process 2 is configured to advertise both the 192.168.1.0 and 192.168.2.0 networks automatically to neighbouring routers.
Unlike static routing, EIGRP only requires you to declare which networks to advertise. The protocol automatically discovers neighbours, exchanges topology tables, and calculates the best path using the DUAL algorithm.
R2 (ISR4331) is the central hub router. GigabitEthernet0/0/0 is at 192.168.3.1/24 (LAN to Switch2). Serial0/1/0 is at 192.168.2.2/24 (WAN to R1) and Serial0/1/1 is at 192.168.4.1/24 (WAN to R3). With EIGRP configured, R2 automatically learns routes from both R1 and R3 and redistributes them — no manual static routes needed.
R3 (ISR4331) is the right-site router. GigabitEthernet0/0/0 is at 192.168.5.1/24 (LAN to Switch1) and Serial0/1/1 is at 192.168.4.2/24 (WAN uplink to R2). Once EIGRP is enabled and networks are declared, R3 automatically forms an adjacency with R2 and learns all remote subnets — 192.168.1.0/24, 192.168.2.0/24, and 192.168.3.0/24 — without any manual configuration.
Switch1 (Cisco 2960 IOS15) on the R3 LAN segment shows FastEthernet0/1 as UP on VLAN 1 — the uplink port connecting to R3's GigabitEthernet0/0/0. All other ports are down as no end devices are connected in this topology. The switch operates purely as a Layer 2 distribution device passing traffic between R3 and the LAN segment.
Running 'show run | section eigrp' on R1 reveals the EIGRP configuration: Process ID 2 is active with two network statements — network 192.168.1.0 (LAN) and network 192.168.2.0 (WAN to R2). The CLI also confirms the EIGRP neighbour adjacency message: '%DUAL-5-NBRCHANGE: IP-EIGRP 2: Neighbor 192.168.2.2 (Serial0/1/0) is up: new adjacency' — proving R1 and R2 have successfully formed an EIGRP neighbour relationship.
EIGRP routers automatically discover neighbours using Hello packets on shared links. Once a neighbour is found, they exchange their full routing tables and maintain the relationship with periodic Hellos — no manual neighbour declaration needed.
R1's routing table after EIGRP convergence shows three EIGRP-learned routes marked with 'D' — D 192.168.3.0/24 via 192.168.2.2, D 192.168.4.0/24 via 192.168.2.2, and D 192.168.5.0/24 via 192.168.2.2, all via Serial0/1/0. The metric [90/2172416] is EIGRP's composite metric calculated by the DUAL algorithm. R1 now has full knowledge of the entire network without any static route configuration.
In Cisco routing tables, 'D' stands for DUAL — EIGRP's Diffusing Update Algorithm. The number in brackets [90/2172416] means Administrative Distance 90 (EIGRP's default) and composite metric 2172416 calculated from bandwidth and delay.
R2's routing table confirms it has learned all remote subnets via EIGRP. D 192.168.1.0/24 is learned via 192.168.2.1 (R1) and D 192.168.5.0/24 is learned via 192.168.4.2 (R3). R2 is directly connected to 192.168.2.0/24, 192.168.3.0/24, and 192.168.4.0/24. The default gateway of last resort points to 192.168.2.1 — confirming full bidirectional routing awareness across the entire WAN.
From R1's CLI, pings to all remote subnets return 100% success (5/5 packets). Ping to 192.168.3.1 (R2 LAN): 8–16ms round-trip. Ping to 192.168.5.1 (R3 LAN): 14–25ms round-trip — the higher latency reflects traffic traversing two Serial WAN hops (R1→R2→R3). Ping to 192.168.4.1 (R3 WAN interface): 5–12ms. All five exclamation marks (!!!!! ) confirm zero packet loss across all paths.
The higher RTT to R3 (14–25ms vs 8–16ms to R2) is expected — traffic must traverse two Serial WAN links instead of one. This demonstrates EIGRP correctly routing traffic through R2 as the intermediate hop to reach R3's network.
The final screenshot shows R1's complete routing table with all D routes present, immediately followed by successful pings to 192.168.3.1 and 192.168.5.1 both returning 100% (5/5). This single screenshot is the definitive proof that EIGRP dynamic routing is fully operational — all routers have converged, routes are automatically distributed, and end-to-end connectivity is confirmed across all 5 subnets.
This network uses zero static routes. Every route marked D was learned automatically by EIGRP — demonstrating the core advantage of dynamic routing protocols over manual static configuration, especially as networks grow larger.
