This counter counts the number of Asynchronous Status update messages received on the port, which report status changes from the far end outside the normal polling cycle. An administrator can use a rising count to spot that the attached device is experiencing PVC or link-state changes it is proactively reporting. For example, an engineer seeing an uptick in this counter around the same time as a customer-reported outage would treat it as corroborating evidence of a change on the customer's equipment.