To be “up/up,” a router VLAN interface must fulfill the following general conditions:

•The VLAN exists and is “active” on the VLAN database of the switch.

•The VLAN interface exists on the router and is not administratively down.

•At least one Layer 2 (access port or trunk) port exists, has a link “up” on this VLAN and is in spanning-tree forwarding state on the VLAN.