Troubleshooting
Commands to display VLAN Information
Display VLAN name, status, and its ports one VLAN per line.
S1# show vlan brief
Display information about a specific VLAN by ID
S1# show vlan id [vlan-id]
Display information about a specific VLAN by Name
S1# show vlan name [vlan-name]
Show a summary of all VLANS
S1# show vlan summary Number of existing VLANs : 12 Number of existing VTP VLANs : 12 Number of existing extended VLANS : 0
Command to confirm that a switchport has been properly assigned to the VLANS required
S1# show interfaces fa0/18 switchport Name: Fa0/18 Switchport: Enabled Administrative Mode: static access Operational Mode: static access Administrative Trunking Encapsulation: dot1q Operational Trunking Encapsulation: native Negotiation of Trunking: Off Access Mode VLAN: 10 (STAFF) Trunking Native Mode VLAN: 1 (default) Voice VLAN: 150 Administrative private-vlan host-association: none (Output omitted)
Verifying a Trunk Link Configuration
Command to Show Interface Switchport Configuration
S1# show interfaces fa0/1 switchport Name: Fa0/1 Switchport: Enabled Administrative Mode: trunk Operational Mode: trunk Administrative Trunking Encapsulation: dot1q Operational Trunking Encapsulation: dot1q Negotiation of Trunking: On Access Mode VLAN: 1 (default) Trunking Native Mode VLAN: 100 (VLAN0100) Administrative Native VLAN tagging: enabled Voice VLAN: none Administrative private-vlan host-association: none Administrative private-vlan mapping: none Administrative private-vlan trunk native VLAN: none Administrative private-vlan trunk Native VLAN tagging: enabled Administrative private-vlan trunk encapsulation: dot1q Administrative private-vlan trunk normal VLANs: none Administrative private-vlan trunk associations: none Administrative private-vlan trunk mappings: none Operational private-vlan: none Trunking VLANs Enabled: ALL Pruning VLANs Enabled: 2-1001 (output omitted)
Verifying DTP Mode
Command to verify DTP Mode
S1# show dtp interface fa0/1 DTP information for FastEthernet0/1: TOS/TAS/TNS: ACCESS/AUTO/ACCESS TOT/TAT/TNT: NATIVE/NEGOTIATE/NATIVE Neighbor address 1: C80084AEF101 Neighbor address 2: 000000000000 Hello timer expiration (sec/state): 11/RUNNING Access timer expiration (sec/state): never/STOPPED Negotiation timer expiration (sec/state): never/STOPPED Multidrop timer expiration (sec/state): never/STOPPED FSM state: S2:ACCESS # times multi & trunk 0 Enabled: yes In STP: no