Timings of Messages and their Responses

Requests and Timeouts

The Timestamp of the very first packet is shifted to the time indicated by the inject.at-timestamp Parameter or to somewhere near the beginning of the pcap file if no Parameter was set. Following requests and timeouts have the general offset among each other as specified in the input file, but are slightly randomized by a value of up to 50ms up or down. However, a request message is only sent after all responses to previous requests have come in, therefore timings may be shifted backwards if responses take too long.

Responses

For Responses, avg_delay_local and avg_delay_external are calculated first. They represent the average delay of a packet in either local or external communication and are calculated from the avg delay in tcp handshakes from the conv_statistics DB Table. If no statistics are available, they are set to a hardcoded value of avg_delay_local=55ms and avg_delay_external=90ms. For every response, it is determined whether it is local or external communication. Depending on that, the respective avg delay value is randomized by up to 10% and then added to the timestamp of the request packet.