The evaluation of performance measurement in computer networks is an important issue. one-way delay (OWD) is an important parameter when considering the quality of service of the network communication. The operating system and, the threads in concurrent with the measurement application are the factors to be consdered for accurate OWD measurement. The synchronization uncertainties make the estimation of the OWD a difficult task. The different available methods for the OWD measurement available in the literature is discussed in this article. The reasonable clock synchronization is ensured based on the Network Time Protocol, the Global Positioning System, and the IEEE 1588 Standard.
The formal definition of OWD can be the OWD is the time between the occurrence of the first bit of a packet on the first observation point, e.g., the
transmitting monitor interface, and the occurrence of the last bit of a packet on the second observation point.
The measurement infrastructures and methodologies become essential in characterizing network performances in the scenario where the computer networks become more complex and larger. Loss and error metrics indicate network congestion conditions. the amount of data that a user can transfer through the network in a time unit is assessed by the Bandwidth metrics. This maybe either dependent or independent of the network traffic. network congestion conditions or the effect of routing changes is assessed by the delay metrics.

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