Miroslav, There is an additional issue, which is perhaps unrelated to the other issues discussed.
Background: Each target IP is a hardware based NTP server. IPs 240 and 244 are across the switch. Chrony is synchronizing with these two IPs. Incremental latency from the switch is approximately ~1.8 microseconds each way. IP 245 is directly attached, and is marked as noselect. With software time stamping, the directly connected unit (IP 245) shows an average offset of approximately +250ns from the reference units. MS Name/IP address Stratum Poll Reach LastRx Last sample =============================================================================== ^+ 192.168.230.240 1 0 377 1 +32ns[ +32ns] +/- 19us ^* 192.168.230.244 1 0 377 1 -47ns[ -76ns] +/- 19us ^? 192.168.230.245 1 0 377 1 +310ns[ +310ns] +/- 16us Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev ============================================================================== 192.168.230.240 58 36 78 -0.000 0.002 -33ns 80ns 192.168.230.244 30 18 41 +0.000 0.005 +25ns 111ns 192.168.230.245 20 16 24 -0.005 0.011 +188ns 87ns With hardware time stamping enabled, this offset just to an average of approximate -2200ns from the reference units. MS Name/IP address Stratum Poll Reach LastRx Last sample =============================================================================== ^* 192.168.230.240 1 0 377 0 -515ns[ -547ns] +/- 13us ^+ 192.168.230.244 1 0 377 0 -454ns[ -486ns] +/- 13us ^? 192.168.230.245 1 0 377 0 -1800ns[-1832ns] +/- 6546ns Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev ============================================================================== 192.168.230.240 64 30 76 -0.002 0.005 -66ns 264ns 192.168.230.244 64 32 76 +0.001 0.005 +66ns 231ns 192.168.230.245 57 33 68 +0.003 0.004 -2036ns 183ns While I can get my head around a differential of 250ns resulting from the switch, I’m finding it very difficult to believe the almost 2500ns differential that appears when hardware time stamping is enabled. Any thoughts on this? Thanks, Denny