This counts Delay Measurement Replies this device has sent back after receiving DMM probes from a remote MEP measuring latency to this device. Because the accuracy of the remote MEP's delay measurement depends on this device timestamping and returning the DMR promptly, this counter's steady increase confirms this device is correctly participating as the reflector in someone else's SLA or latency-monitoring test. If a remote provider reports this device is not responding to their delay-measurement probes but this counter shows DMRs going out at the expected rate, the issue is more likely on the return path than at this device.