Port down and aging

Aging is only used as a safeguard. If a unit is powered down or the stacking link is removed, the system immediately detects that the port is down and knows that its neighbor is gone. That unit is immediately removed from the active controller.

If a stacking port does not receive keep-alive messages from its neighbor within 60 seconds, it ages out the neighbor. When a unit is no longer stack-enabled or when one stacking port becomes a non-stacking port, it sends a notification that the port is no longer a stacking port. When the neighboring port receives the notification from its neighbor, it immediately removes the neighbor.

The following message is logged and displayed when a port is aged out.

Warning! my mac=0000.004f.4243, age out up-stream