The upper diagram shows accuracy and stability of the local clock loop. This is an IBM RS/6000 type 7044 model 270 with four 375 MHz Power3 processors, 3 GB RAM, two 100 MBps Ethernet adapters and an UPS. It's the server for our SAP® R/3® system but fairly fast. This stratum-2 server running NTP version 4 is not publicly available, but for our internal use only. These new RS/6000 machines are good timekeepers in contrast to the older ones (compare 'kim'). (ppm: pulses per minute)

Time and frequency standard deviations roughly follow the respective offsets: