This counter tracks the total number of EIGRP routing update packets received from all neighbors in this autonomous system. A persistently high rate of received updates over a timeframe, as opposed to occasional expected changes, suggests instability somewhere upstream in the topology, even if this router's own links are stable, since it's still having to process and potentially recompute routes for every incoming update. If this counter keeps climbing steadily over a long period without any known network changes, an admin would suspect a remote neighbor or its own upstream links are flapping and generating continuous update traffic.