Chapter 4. InterVLAN Routing
VLANs divide the network into smaller broadcast domains but also prohibit communication between domains. To enable communication between those groups–without also passing broadcasts–routing is used.
InterVLAN Routing Using an External Router
A Layer 2 switch can connect to a router to provide reachability between VLANs. This can be done either via separate physical links for each VLAN or via a trunk link from the switch to the router. A trunk link is most common and this type of setup is frequently called Router on a Stick.
When using a trunk link you must create separate subinterfaces on the router’s physical interface—one subinterface for each VLAN plus one for the native VLAN. This can work ...