Asymmetry between the forward and reverse path Oscillator behavior and clock recovery accuracy (including filtering) on the slave node Obviously, this means that the more network nodes involved in the transport of time, the worse the result is at the end of the chain. The timing standards define sets of performance metrics for timing characteristics SO that engineers can predict what level of accuracy can be expected after transporta- tion across the network. This separates equipment into different categories of performance and places limits on the topology that each equipment type can support, while still delivering an accept- able result. Additionally, ensuring the shortest path to the best reference is a fundamental goal of good timing network design. Because the timing signal degrades as it crosses every link or node, then being able to determine the path length (and dynamically recalculate it following a network rearrangement) is also valuable. And yet another reason that can lead to further significant divergence between two clocks in a network is that they are not connected to the best source of time. This could happen due to reasons such as Nodes are receiving a clock signal from a time source of dubious accuracy. The packet master is using a reference clock that is no longer a valid source of frequency, phase, and time. The slave selects a master clock that is not the best available. A node is synchronized with a clock that has lost connection to its reference and does not know The conclusion from these possible issues is that slave clocks not only need a timing signal but also need to understand how good that signal is and whether it comes from a good source. The notion of traceability was developed to solve this problem. In metrology, traceability is defined as a situation where "the [measured timing] result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty." Therefore, just about all timing distribution mechanisms, both 