It is difficult to debug problems with speech quality, one way voice, or lost calls on the Internet and in enterprises spread over different locations. One reason for the difficulty is the large number of paths that a packet can take through the network. In the case of voice, the path a packet takes can determine if the call is intelligible by the voice call participants. This is due to the tight delay budget required for voice packets to travel end to end. Thus, a need exists for tracking the path of the voice traffic so that problems related to packet loss and packet delays can be identified. The problem becomes even more critical when the endpoints require video and lip synchronization.
A User Datagram Protocol (UDP) traceroute is currently used to identify problems in Internet Protocol (IP) networks. The UDP traceroute uses ephemeral source and destination ports and makes special use of the IP Time To Live (TTL) value. The TTL value in the traceroute is varied to isolate a trouble spot in the IP network. For example, the first traceroute packet may be sent with a TTL value of “1”. The first node receiving the traceroute packet decrements the TTL value by one. As the TTL value is now zero, the first node sends a fault notice back to the source.
A second traceroute packet is sent with a TTL value of “2”. The source expects a fault notice back from a second node receiving the traceroute packet. However, if the fault notice comes back from the first node, or if no fault notice comes back, then a trouble spot in the network can be isolated somewhere between the first node and second node.
The UDP traceroutes are not effective in detecting network problems for IP media streams. This is because the UDP traceroute packets do not necessarily travel along the media path used by the IP media stream. It does no good identifying a problem node in a network, if the identified node is not used in the media stream path.
The UDP traceroute packets also cannot pass through firewalls that may exist between a source endpoint and a destination endpoint for the media session. Since UDP traceroute packets may not be able to travel the entire path from the source endpoint to the destination endpoint, they are unreliable for analyzing the entire media path for IP media streams.
The present invention addresses this and other problems associated with the prior art.