|This article does not cite any references or sources. (July 2009)|
The ping utility calculates the RTT, that is, the time to go and come back to a host. This does not assure that the go and back paths are the same in terms of congestion, number of hops, or Quality of Service (QoS).
In order to avoid such problems, OWD concept comes into play. The One-Way Delay value is calculated between two synchronized points A and B of an IP network, and it is the time in seconds that a packet spends in travelling across the IP network from A to B. The transmitted packets need to be identified at source and destination in order to avoid packet loss or packet reordering.
The measurement method makes obvious that this value is substantially different from the Round-Trip Time/2 value.