This counts how many 'hello' keepalive PDUs this circuit's called (receiving) side has received as part of Cascade's PVC establishment and keepalive signaling, giving the admin a way to confirm that hello-based signaling is actually flowing rather than assuming operational status alone tells the full story. For example, a circuit reporting cktOperStatus active but a cktHelloCounter that hasn't incremented in the last several polling intervals would suggest the keepalive signaling itself has stalled even though the data path still shows up.