This value specifies, in seconds (1 to 10), how long to wait for an SLM reply in a two-way test before assuming it won't arrive; any reply received after this timeout is silently discarded. An admin sets this based on the expected round-trip time of the path being tested, long enough to avoid false loss detection but short enough to keep the test responsive. Setting this too short on a high-latency path can cause the test to report loss for replies that were actually just slow, not lost.