This work deals with the concept of network synchronization. The process of work regarding two protocols (NTP and PTP) that support network synchronization over packages is described. Emphasis is placed on the metrics in reference point C of the network reference model, defined in the ITU-T G.8271.1 recommendation standard and filters using them. We distinguish several types of filters, but for the purposes of this work, the most significant are low pass and high pass filters. The low pass filter passes low-frequency signals from 0 Hz to cut-off frequency, ƒc (0.1 Hz) while blocking all higher frequency signals. On the other hand, the high pass filter allows the passage only to high-frequency signals from cutoff frequency, ƒc and all the way to infinity, and attenuates lower frequencies. Max|TEL| and MTIE requirements are applicable for frequency components lower that 0.1 Hz, while peak-to-peak dTEH(t) is applicable for components higher that 0.1 Hz. The practical realization of first order digital filters was made based on two trace files, using several infinite impulse response filters (IIR), namely Butterworth, Chebyshev type 1 and 2, Elliptic and a simple RC filter. IIR filters were used in the analysis, since they require fewer parameters, less need for memory and less computational complexity. Also, for testing the filter, the Matlab multifunctional programming language was used, within which the PTP analyzer tool for analysis was used and the PTP simulator to define the methods of the above filters. These methods return the coefficients of the transmission function. Since for further research we want to confirm and find filters that will result in the behavior of the system in which the metrics completely accurately show what we have at the input of the node, that is, what amount of TE is, the concept of supervision and package selection is described.