incomplete

Address resolution is currently being performed on this neighbor entry. A neighbor solicitation message has been sent, but a reply has not yet been received.

reachable

Address resolution has determined that the neighbor is reachable. Positive confirmation has been received, and the path to this neighbor is operationable.

stale

More than the configured elapsed time has passed since reachability confirmation was received from this neighbor.

delay

More than the configured elapsed time has passed since reachability confirmation was received from this neighbor. This state allows TCP to confirm the neighbor. If not, a probe should be sent after the next delay time has elapsed.

probe

A solicitation has been sent, and the router is waiting for a response from this neighbor.

failed

Neighbor reachability state detection failed.

noarp

The neighbor entry is valid. There are no attempts to validate it, but the neighbor can be removed from the cache when its lifetime expires.

permanent

The neighbor entry is valid indefinitely and should not be cleared from the cache.

none

No state is defined.