Map the network
You've inherited a network with no diagram, and you're on ACC1's console. Use CDP (and LLDP where you need it) to find out what's connected where. Then harden ACC1: stop CDP on Fa0/5, the port facing the user's PC.
How it works: this is VulnTech NetLab, a network simulator running in your browser. Click a device in the diagram to open its console and type commands, just like on real equipment (? shows help, Tab finishes a word). Click a cable to inspect it. Tasks tick themselves off as you complete them; questions are answered in the box under each task. Your work is kept if you reload; Reset starts the network over.
Solution explanation
CDP only shows directly connected devices, so you hop from device to device: ACC1 sees CORE1 on Gi0/1 (CORE1's Fa0/1); on CORE1, show cdp neighbors detail shows R1 and its address 10.0.0.1. LLDP is off by default on Cisco devices and must run on both ends. no cdp enable stops CDP on one interface; no cdp run would stop it everywhere, including towards CORE1.
Show solution
[ACC1]
enable
show cdp neighbors
configure terminal
interface fa0/5
no cdp enable
end
[CORE1]
enable
show cdp neighbors
show cdp neighbors detail
configure terminal
lldp run
end
[ACC2]
enable
configure terminal
lldp run
end
[CORE1]
show lldp neighbors