This Counter64 field reports the bytes transmitted per second on the reverse direction of this bidirectional CES tunnel, as computed for this PM instance. Because this is the currently open, still-accumulating measurement interval that keeps climbing until its boundary is reached and it rolls off into the history table, and this specific field is an instantaneous computed rate of transmitted egress traffic rather than a running total, so a spike here shows up the moment it happens rather than only after the interval ends, it is the field to check when you need to see the reverse-direction egress throughput of the tunnel right now rather than a cumulative volume. For example, this counter might read 4,234 bytes/sec during the in-progress 15-minute bin — a sudden jump to several times that on the reverse side, with no matching rise on the other direction, would point to a one-way traffic surge or an attack riding that leg of the tunnel.