Router-on-a-Stick Troubleshooting Capstone
Bundle lab
Advanced CCNA capstone: diagnose and repair a fully-broken three-VLAN router-on-a-stick deployment. One iol-xe router uplinks by 802.1Q trunk to a pure layer-2 ioll2-xe switch, with three alpine PCs on their own access VLANs (10 Sales, 20 Voice, 30 CCTV); after a recent switch and router change, inter-VLAN connectivity is broken or intermittent across all three VLANs. Trace VLAN intent end-to-end from each host through the trunk to the router's subinterfaces, repair whatever faults you find, and verify with end-host pings/traceroutes and IOS show commands.
Learning objectives
- Trace end-to-end VLAN intent across access and trunk ports in a router-on-a-stick design
- Configure and verify router 802.1Q subinterfaces with correct VLAN tags and gateway IPs
- Identify and correct native VLAN mismatches
- Detect and restore missing VLANs on trunk allow-lists
- Prove inter-VLAN forwarding from hosts and validate router and switch state with IOS show commands
Troubleshooting focus
- Detect a missing subinterface for a user VLAN on the router
- Correct an incorrect 802.1Q encapsulation tag on a router subinterface
- Identify a VLAN pruned from the switch trunk allow-list and permit it
- Resolve native VLAN mismatch between router subinterface and switch trunk
Topology
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How this lab is graded
- Build it your way. Where a lab lets you choose a value — a VLAN name, an interface description — grading checks that you configured it, not which name you picked. Names that another line has to reference, like an ACL applied with
access-class, are stated in the guide and do have to match. - Addresses, modes and protocol keywords are exact. An IP address, a subnet mask,
switchport mode trunk, an encapsulation — these carry the meaning of the lab, so they are graded as written in the guide. - Grading reads your saved configuration. Export the lab from CML after you have configured it, and make sure anything you set is in the running-config — a change that only exists in a terminal session never reaches the grader.
- You can submit as many times as you like. Your best score stands, and each attempt tells you which checks passed so you can work the gaps.
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