Physical links between an access switch and a pair aggregation switches are aggregated into a virtual link aggregation group (vLAG). Each aggregation switch is a local switch to itself and a remote switch to the other aggregation switch. Each aggregation switch maintains a state machine including initialization, local-up, remote-up, and formed states. In the initialization state, the physical link between the access switch and each aggregation switch is down, and the vLAG is down. In the local-up state, just the physical link between the access switch and the local switch is up, and the vLAG is down. In the remote-up state, just the physical link between the access switch and the remote switch is up, and the vLAG is down. In the formed state, the physical link between the access switch and each aggregation switch is up, and the vLAG is up.