IPv6 Neighbor Discovery: Default Gateway Failure
IPv6 Neighbor Discovery replaces several familiar IPv4 functions and supplies the default gateway through router advertisements. This lab shows why an address alone does not prove end-to-end IPv6 connectivity.
The problem
A host has a SLAAC address in the correct /64 but no IPv6 default route because the router's advertisements are suppressed on the user-facing interface.
What you'll practice
- Inspect IPv6 host routes
- Explain router-advertisement default-router information
- Verify ND state
- Restore off-link IPv6 connectivity
The topology
A router serves one user VLAN and provides the only path to an upstream IPv6 network.
Commands to run yourself
The real diagnostic commands for this lab, copy-paste ready. Run these in the same order to reproduce the investigation on your own session.
show ipv6 interface Ethernet1/0show ipv6 routeshow ipv6 neighborsTopology diagram
Frequently asked
Is this aligned to CCNA practice?
Yes. It focuses on configuration, verification, and troubleshooting skills covered by the CCNA-level technology domain named on this lab.
Ready to run this lab yourself?
No setup, no image sourcing. Book a session or ask for a live demo.