ropagation delay. This refers to the time that an IP packet requires to be sent by the sender over a given link and received by the node on the other end of the link. Due to maximum speed limit (that is speed of light, approximately 3 X 108 m s) longer link results in bigger propagation delay. That is one of the main reasons for use of CDNs for OTT data services (to limit the propagation delay between the user clients and the servers). Queuing delay. This refers to the time that packet waits in a queue in network nodes (e.g. routers, switches) before it is transmitted over the next link (i.e. next hop). At high traffic intensity the queue length is longer and hence the queuing delay and delay variation (i.e. jitter) have bigger values. Both the average delay and the jitter matter for real-time conversational services (the highest importance) and for interactive services (e.g. Web browsing) with medium to low importance. Packet loss. This parameter refers to the probability that an IP packet never reaches its destination. There are several potential reasons for packet loss to occur which also include the transmission errors, but one should note that they appear with very low probability in fiber fixed access and transport networks (e.g. 10-8-10-9 error probability, which results in the time period between consecutive loss periods being measured in hours). In practice, in fixed networks IP packets are mainly lost when the queues are full due to the number of packets waiting for transmission is becom- ing greater than the available storage capacity in the buffers. Additionally, TCP always results in losses when TCP congestion window reaches the bottleneck capacity for the given TCP connection (however, all lost packets due to any causes are retransmitted by using TCP retransmissions). One should note that the error probability in mobile access networks is much higher (e.g. 10-2-10-3) in the macrocellular environment, which may influence the data transmission rate for TCP-based services (e.g. Web ser- vices) or real-