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Set B 125usec Packet Inter-Arrival Time
The following section discusses the difference between automatically allowing the interface to detect the line speed and explicitly setting the line speed of an interface for 125usec packet inter-arrival time for Set B.
As we can see from Figures 26 to 29 below, both allowing the line speed to be automatically detected and explicitly setting it results in a very similar time stamp pattern. It is obvious that time stamping with this NIC is not improved when the line speed is statically set.
Figure 26: Automatic 10Mbit/sec Figure 27: Explicit 10Mbit/sec Figure 28: Automatic 100Mbit/sec Figure 29: Explicit 100Mbit/sec
Tables 21 to 24 show that for all configurations the varience and the standard deviation were very high. The mean, however, is still near the 203usec for the 10Mbit/sec line speed and 133.3usec for the 100Mbit/sec line speed as expected. This tells is that the majority of time stamps are still centered around the theoretical mean values although the far outliers affect the varience and standard deviation.
Table 21: Automatic 10Mbit/sec (usec)
Mean Varience Standard Deviation 208.00 11334.11 106.46
Table 22: Explicit 10Mbit/sec (usec)
Mean Varience Standard Deviation 208.00 10334.55 101.66
Table 23: Automatic 100Mbit/sec (usec)
Mean Varience Standard Deviation 133.32 6920.91 83.19
Table 24: Explicit 100Mbit/sec (usec)
Mean Varience Standard Deviation 133.32 5497.35 74.14
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