Set E 500usec Packet Inter-Arrival Time
The following section shows the difference between automatically allowing the interface to detect the line speed and explicitly setting the line speed of an interface for 500usec packet inter-arrival time.
When the fxp1 interface was physically removed from the PC, it can be seen in Figures 34 to 37 that time stamp accuracy was slightly improved by explicitly configuring the line speed.
Figure 34: Automatic 10Mbit/sec Figure 35: Explicit 10Mbit/sec Figure 36: Automatic 100Mbit/sec Figure 37: Explicit 100Mbit/sec
The Tables below support the visual conclusion of improved time stamp accuracy upon explicit line speed configuration. This improvement is, however, only minimal.
Table 33: Automatic 10Mbit/sec (usec)
Mean Variance Standard Deviation 583.250 0.997 0.998
Table 34: Explicit 10Mbit/sec (usec)
Mean Variance Standard Deviation 583.251 0.928 0.963
Table 35: Automatic 100Mbit/sec (usec)
Mean Variance Standard Deviation 508.364 0.996 0.998
Table 36: Explicit 100Mbit/sec (usec)
Mean Variance Standard Deviation 508.364 0.954 0.977
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