Patent ID: 7454494

Claim:
In a packet network communications system, a method of analyzing packet-delivery performance along intermediate path segments during a communications session between a source and destination for a predetermined application, comprising the steps of: (A) establishing a communications session between a source and a destination by a call signaling exchange between the source and the destination, the communications session being that period between a call answer signal from the destination and a call termination condition; (B-1) sending data packets between the source and the destination during the communications session; (B-2) sending diagnostic packets from the source during the same packet communication session in which the data packets are transmitted between the source and destination, each diagnostic packet being of same format as data packets delivered during the communications session, each diagnostic packet eliciting a response from a router along a path between the source and destination; and (C) analyzing the responses from routers along at least one path to produce a packet-delivery metric for one or more of the routers along one or more paths between the source and the destination, wherein each diagnostic packet is of the same length as data packets being transmitted in the communications session, each diagnostic packet including: the same user datagram protocol (UDP) destination port number as data packets, the same differential services code point as the data packets, and a real time protocol (RTP) header that is valid for the data being transmitted in the communications session.