This counter tracks the total number of packets received from the 'Endstation' -- the locally attached terrestrial equipment -- that are queued to be sent out one of the router's other interfaces. This counter reflects traffic originating from equipment plugged directly into the CDD-564's local data port rather than from the LAN or the satellite link, so it's the metric to watch when troubleshooting whether locally-connected gear is actually generating traffic for the router to relay. If a technician connects a new serial data device to the Endstation port expecting it to be routed over satellite, verifying this counter increments confirms the device's packets are reaching the router before checking whether they successfully egress on the satellite side.