How do you identify a switch access port issue causing inter-VLAN connectivity failure?

The typical symptom is a PC with correct IP (Internet Protocol) configuration that can't ping its default gateway — verify the port's VLAN (Virtual Local Area Network) assignment with show interfaces switchport or show vlan brief.

Common access port problems:

1. Port assigned to wrong VLAN — host is in VLAN 1 (default) instead of the intended VLAN
2. Port in trunk mode instead of access — an access device on a trunk port won't work correctly
3. Port is shut down — administratively disabled

Detection:

S1# show interface fa0/6 switchport

Key lines to check:

• Administrative Mode: static access — confirms it's an access port
• Access Mode VLAN: 1 (default) — if this says VLAN 1 but should be VLAN 10, that's the problem

A classic gotcha: If the port shows Access Mode VLAN: 1 (default), the switchport access vlan command was never applied. All ports default to VLAN 1 until explicitly assigned.

Fix:

S1(config)# interface fa0/6
S1(config-if)# switchport mode access
S1(config-if)# switchport access vlan 10

Go deeper:

• Troubleshoot Inter-VLAN Routing (Cisco Press) — hosts stranded on a wrong-VLAN access port, verified with show interfaces switchport.