Objectives
| # | Objective |
|---|
| 1 | Create VLAN 10 (Sales) and VLAN 20 (Engineering) on SW1 |
| 2 | Assign access ports to their correct VLANs |
| 3 | Verify VLAN assignment and port membership with show commands |
| 4 | Confirm intra-VLAN connectivity — PCs in same VLAN can ping |
| 5 | Confirm inter-VLAN isolation — PCs in different VLANs cannot ping |
| 6 | Troubleshoot a port assigned to the wrong VLAN |
| 7 | Knowledge check — VLAN fundamentals |
Key Concepts
| Concept | What it means |
|---|
| VLAN | Virtual LAN — logically partitions a switch into separate broadcast domains, even though devices share the same physical hardware. |
| Access port | A switch port that belongs to exactly one VLAN. Frames arrive and leave untagged. Used for end-device connections (PCs, printers). |
| Broadcast domain | The set of devices that receive a broadcast frame. VLANs define broadcast domain boundaries — broadcasts don't cross VLAN boundaries. |
| VLAN isolation | Devices in different VLANs cannot communicate at Layer 2. A Layer 3 device (router or L3 switch) is required to route between VLANs. |
| VLAN 1 | The default VLAN. All ports start here. Best practice: move data ports off VLAN 1. |
Topology
| Device | IP Address | VLAN | SW1 Port |
|---|
| PC1-Sales | 192.168.10.10/24 | VLAN 10 (Sales) | Gi0/0 |
| PC2-Sales | 192.168.10.11/24 | VLAN 10 (Sales) | Gi0/1 |
| PC3-Eng | 192.168.20.10/24 | VLAN 20 (Engineering) | Gi0/2 |
| PC4-Eng | 192.168.20.11/24 | VLAN 20 (Engineering) | Gi0/3 |
Key Commands — SW1
| Command | Purpose |
|---|
| vlan 10 | Create VLAN 10 (in global config mode) |
| name Sales | Name a VLAN (in vlan config mode) |
| interface Gi0/0 | Enter interface config |
| switchport mode access | Set port as access port |
| switchport access vlan 10 | Assign port to VLAN 10 |
| show vlan brief | List all VLANs and member ports |
| show interfaces Gi0/0 switchport | Check access VLAN for a specific port |
| show mac address-table | See which MACs/VLANs are on which ports |
Use Tab to complete commands · ↑ ↓ for history · Devices share the same switch — only VLANs separate them.
You must create the VLAN on the switch before assigning ports to it. Assigning a port to a non-existent VLAN still works on Cisco IOS but the VLAN will be inactive until created.