Open the lab
[ YOUR LAB FILE ]
Download the starting topology, then work through the lesson in SwitchLab.
- Save the .swlab file without renaming its extension.
- Open SwitchLab. Import and export controls currently require a desktop-width window. On a smaller screen, Tools → Fit brings the topology into view.
- Select Import Sandbox (folder icon), choose the downloaded file, and confirm the device and cable counts below.
- Select a device, then choose Open device on desktop or its name in the bottom bar on smaller screens. Select CLI for switches/routers or Desktop → Terminal for PCs. Enter
enableonly when the prompt ends in >. - Follow this page beside the simulator. Use a free account to export your work. Reimport the original download to restart; export any work you want to keep first.
Prerequisites
- Complete the VLAN Guided Lab and interpret access-port and trunk tables.
- Recognize the difference between a host subnet, an access VLAN and an 802.1Q trunk.
Topology
6 devices · 5 links
Scenario
A staff workstation lost access after its wall outlet was moved to another switch port. Student traffic between closets still works. Restore the staff connection while preserving the department separation.
Objectives
- Inspect the local access-port membership before changing a trunk.
- Repair one access-port assignment without changing host addresses.
- Prove staff delivery in both directions and retain student connectivity.
CCNA blueprint
200-301 v1.1 objectives — this lab covers the following specific skills, not every subtopic in the domain.
- 2.1.a — Data access-port VLAN assignment across two switches (voice VLAN is outside this lab).
- 2.2.a — Trunk ports carrying multiple VLANs.
- 2.2.b — 802.1Q VLAN tagging on the interswitch link.
Starting information
- On SW2, PC4 is physically connected to g0/2. It must belong to STAFF VLAN 20. Its configured IPv4 address is correct.
- PC1 and PC3 are students; PC2 and PC4 are staff. Keep the addressing and physical cabling shown below.
- No router is present. Inter-department traffic is not a success condition for this Layer 2 repair.
| Host | IPv4 address | Mask | Gateway |
|---|---|---|---|
| PC1 | 192.168.10.10 | 255.255.255.0 | None |
| PC2 | 192.168.20.20 | 255.255.255.0 | None |
| PC3 | 192.168.10.30 | 255.255.255.0 | None |
| PC4 | 192.168.20.40 | 255.255.255.0 | None |
| Device / port | Device / port |
|---|---|
| PC1 / eth0 | SW1 / g0/1 |
| PC2 / eth0 | SW1 / g0/2 |
| SW1 / g0/8 | SW2 / g0/8 |
| PC3 / eth0 | SW2 / g0/1 |
| PC4 / eth0 | SW2 / g0/2 |
Tasks
- Predict whether a total uplink outage would explain the reported symptom. Test the student path and the staff path before changing anything.
- Inspect VLAN membership, both trunk tables and the relevant interface configurations. Record the discrepancy and explain how it prevents the failed path.
- Apply the smallest correction consistent with the approved starting information. Preserve all addresses, cables and working department settings.
- Repeat both directions of staff traffic and both directions of student traffic. Compare the repaired configuration with your diagnosis, then save the switch configuration.
Useful commands
show vlan brief
show interfaces trunk
show running-config
show running-config interface g0/2
copy running-config startup-configProgressive hints
Hint 1
Compare PC4’s address and department with its switch access-port membership. Keep the working student connection as a control.
Hint 2
An access port places untagged host traffic into one VLAN. Matching IP subnets cannot override incorrect VLAN membership.
Hint 3
Inspect SW2 g0/2 with show running-config interface g0/2; select the STAFF VLAN on that port.
Verification
- On SW2, PC4 is physically connected to g0/2. It must belong to STAFF VLAN 20. Its configured IPv4 address is correct.
- PC1 → 192.168.10.30 and PC3 → 192.168.10.10 succeed.
- PC2 → 192.168.20.40 and PC4 → 192.168.20.20 succeed.
- Inspect the corrected interface configuration; successful pings must not come from flattening the VLAN design.
Solution / walkthrough
Show Solution
Use enable only from a > prompt; if already at #, begin with configure terminal.
SW2
Apply the approved access-port membership on SW2. The student path provides a control before and after the repair; verify the staff path separately.
enable
configure terminal
interface g0/2
switchport access vlan 20
end
copy running-config startup-configRun every verification check above after the changes. A saved configuration alone does not prove packet delivery.