The issues common to legacy inter-VLAN routing and router-on-a-stick inter-VLAN routing are also manifested in the context of Layer 3 switching. To troubleshoot Layer 3 switching issues, the following items should be checked for accuracy:
- VLANs - VLANs must be defined across all the switches. VLANs must be enabled on the trunk ports. Ports must be in the right VLANs.
- SVIs - SVI must have the correct IP address or subnet mask. SVI must be up. SVI must match with the VLAN number.
- Routing - Routing must be enabled. Each interface or network should be added to the routing protocol.
- Hosts - Hosts must have the correct IP address or subnet mask. Hosts must have a default gateway associated with an SVI or routed port.
To troubleshoot the Layer 3 switching problems, be familiar with the implementation and design layout of the topology.