This Counter64 counts the number of good AH decrypted packets processed on this Virtual Interface, per its description, the packet-level counterpart to the SA-level establishment counters above. An admin watches this as the primary throughput indicator for this specific protocol/direction combination, expecting it to climb steadily whenever the tunnel is actively carrying traffic. For example, an admin verifying that a newly built AH tunnel on VI 22 on a hub-site aggregation link is actually carrying user traffic would confirm this good-packet counter is incrementing, not stuck at zero.