RTP Packet Profile for Accurate VoIP Route Tracing
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Solution Overview
Problem
Current methods for tracing the route and determining round-trip-times in packet networks transmitting multimedia, such as VoIP, face challenges due to differences in IP protocol, port numbers, Quality of Service treatment, and firewall interactions between traceroute packets and actual media packets, leading to inaccurate route tracing and round-trip-time calculations.
Innovation Solution
The use of RTP packets with a specially defined profile to determine traceroute and round-trip-time information, ensuring they have the same characteristics as media stream packets, including UDP source and destination ports, and utilizing RSVP reservations for consistent network treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ICMP or UDP packets are used for traceroute, then route tracing capability is achieved, but the packets follow different network paths and receive different QoS treatment compared to RTP packets
Solution Approach 1:
The patent changes the packet type parameter from ICMP/UDP to RTP packets, and modifies the RTP packet profile parameters (setting specific values for sequence number, timestamp, and payload type) to enable traceroute functionality while maintaining identical treatment by network elements as media packets
Solution Approach 2:
The patent creates a copy of the actual media RTP packet profile and uses it for traceroute, ensuring that the traceroute packets are identical copies of real media packets in terms of protocol structure, port numbers, and network treatment characteristics
2Adaptability or versatility
If different UDP source and destination ports are used for traceroute packets, then port recognition issues are avoided, but firewall blocking and gateway filtering occur
Solution Approach 1:
The patent changes the port number parameters to match the actual media stream ports exactly, and modifies the RTP packet profile to specify these matching ports, thereby eliminating firewall blocking while maintaining traceroute functionality
3Measurement precision
If RTCP packets are used for RTT determination, then timing information can be obtained, but different packet sizes and transmission rates cause different network treatment compared to RTP packets
Solution Approach 1:
The patent changes the packet type from RTCP to RTP, and modifies the RTP packet profile parameters (sequence number progression, timestamp intervals, payload type) to enable RTT measurement while ensuring identical network treatment as media packets
Data Source
AI summary
An apparatus and method that use media packets, such as Real-time Transport Protocol (RTP), packets with a specially define profile to determine the route and round-trip-time information. The route is determined by transmitting by a first network endpoint one or a group of media packets having a number of hops equal to a predefined number and the network address of a second endpoint, incrementing the number of hops upon a non-media packet being received in response to the one or group by a network node because the number of hops was exceeded at that network node. After recording the identification of that network node and incrementing the number of hops, the network endpoint re-transmits the one or group of media packets. The round-trip-time information is determined by timestamp information inserted into the one or group of media packets by the first network endpoint and timestamp information inserted into another one or another group of media packets transmitted from the second network endpoint to the first network endpoint in response to receipt of the one or group of media packets.