This Counter64 tallies the total number of frames transmitted out through this circuit toward its destination, the egress counterpart to circuitInFrames on the ingress side. Comparing this against circuitInFrames over the same period tells an admin whether frames are being lost somewhere within the circuit's own switching/ring path, distinct from the ingress-side discards already tracked by circuitInFramesDiscard. For example, if circuitInFrames minus circuitInFramesDiscard doesn't roughly match circuitOutFrames over time, that unexplained gap points to loss happening inside the ring itself rather than at the ingress admission point.