Port Gig0/1, where R4 was connected, was in VLAN 1. But the trunk port connecting this switch to the rest of the topology was allowing VLANs 10, 20, and 30. Not VLAN 1.
Neighbor ID Pri State Dead Time Address 10.0.1.1 1 FULL/DR 00:00:37 10.0.14.1
A small victory: the command took. But still, no hello packets. No DR election. Just a cold, digital void.
Leo clicked on R4’s CLI window. The familiar black and green text felt like an old friend, albeit a sarcastic one. cisco packet tracer exercises
It was a silent, perfect, evil mistake. The router was shouting "Hello!" into a VLAN that vanished the moment it hit the trunk. The digital voice was being erased before it could travel a single hop.
He leaned back, the cheap plastic chair groaning in sympathy. His roommate, Maya, had abandoned him an hour ago, muttering something about "sane people sleeping." The only light came from his monitor and the faint blue glow of the server rack in the corner. Packet Tracer hummed quietly, a low, digital thrum.
He went back to basics. He checked the interfaces. Up/up. IP addresses? Correct. The network statement? He retyped it carefully: Port Gig0/1, where R4 was connected, was in VLAN 1
A cheer erupted from Leo’s throat, startling a janitor who was mopping the hallway outside. It was just a simulation. Just virtual routers on a virtual network built by a virtual software company. But the feeling was real. The puzzle had been solved. The pieces had clicked.
Layer 2. The switch. The invisible plumbing.
He held his breath. He clicked back to R4. Neighbor ID Pri State Dead Time Address 10
R4(config-router)#network 10.0.4.0 0.0.0.255 area 0
It was the capstone of CNT-210, and Professor Voss had designed it with the precision of a medieval torturer. Four routers—R1 in Chicago, R2 in Dallas, R3 in Atlanta, R4 in Seattle. Each one was misconfigured in a unique, maddening way. R1 had a passive-interface set wrong. R2 was advertising a route to a network that didn't exist. R3 had an OSPF cost of 1 on a T1 line, creating a routing loop the size of Texas. And R4… R4 just refused to speak to anyone.
Leo double-clicked the switch connecting R4 to the rest of the world, a humble 2960 model. He ran a quick show vlan brief . His heart stopped.
R4#show ip ospf neighbor
R4#show ip ospf neighbor