Chapters
Narration transcript
The English narration in this video. Select a time to watch that moment.
Start with the cable and ports
R1 and R2 are connected. R3 has no cable.
Check the selected devices before changing a connection.
Neighbor output should match the devices and ports on this canvas.
Identify the directly connected neighbor
The Device ID identifies the directly connected neighbor: R2.
Local Intrfce is the port on R1. Port ID is the port on R2.
R3 is absent because it is not connected to this link.
Enable and inspect LLDP
This lab starts with LLDP disabled. Use privileged EXEC before configuring it.
Return to EXEC mode and save the change on each device.
LLDP reports the same neighbor and the same pair of physical ports.
Match an IP address to a MAC address
Test the directly connected address: 10.0.12.2.
The warm test must show 100 percent replies on this healthy link.
ARP maps the peer IP address to its MAC address on Gi0/0.
A cached address mapping alone does not prove that the link is working.
Diagnose a disconnected cable
Disconnect asks you to confirm which connection will be removed.
The address is still configured, but the interface and line protocol are down.
The disconnected device is no longer reported as an adjacent neighbor.
The traffic test now fails. Check the cable before changing IP settings.
Restore the link and verify
Reconnect the same devices on the same Gi0/0 ports.
Both discovery protocols identify R2 again. R3 remains unconnected.
Confirm 100 percent replies after the link is restored.
Check the cable, neighbor identity, address mapping, then actual traffic.