Real-time transport protocol stream detection system and method

• US 20080056302A1
• Filed: 08/29/2006
• Published: 03/06/2008
• Est. Priority Date: 08/29/2006
• Status: Active Grant

• Current Assignee: EXFO Incorporated (11172239 Canada, Inc.)
• Original Assignee: Brix Networks, Inc. (11172239 Canada, Inc.)
• Inventors: Erdal, Muhammet, Hedayat, Kaynam
• Granted Patent: US 8,306,063 B2
• Time in Patent Office: Days
• US Class Current: 370/474
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/65 Network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP]
• CPC Class Codes: H04L 65/80 Responding to QoS

Abstract

A system and method for identifying UDP packets on an IP network as candidates for characterization as packets of a RTP stream. UDP packets are identified at a point on the IP network, and for each identified UDP packet 1) it is determined if a version number in a RTP header field in the payload of the UDP packet equals a predetermined value, 2) determined if a packet length associated with the UDP packet is within a predetermined range, 3) determined if a payload type RTP header field within the payload of the UDP packet is within a predetermined range. If all the criteria are satisfied, then the identified UDP packet is characterized as a candidate RTP packet. It is then determined if the candidate RTP packet belongs to a previously detected RTP stream, or to a newly encountered RTP stream. A stream data store is then updated using the information in the RTP header of the candidate RTP packet.

Claims

1. A method for identifying UDP packets on an IP network which are candidates for characterization as a RTP packet of a Real Time Transport Protocol (RTP) stream, each of said UDP packets having a UDP header and a payload, wherein the payload potentially includes a RTP packet having a RTP header and a RTP payload, wherein said RTP header includes a field for including a version number value representative of an RTP specification version number associated with said RTP packet, a field for including a payload type value representative of a payload type associated with said RTP packet, a field for including a sequence number value representative of a sequence number associated with said RTP packet, and a field for including an SSRC value representative of a synchronization source associated with said RTP packet, and wherein each of said UDP packet headers includes a field for packet length corresponding to the size of said UDP packet, comprising the steps of:

identifying UDP packets at a point on said IP network, and for each identified UDP packet performing the substeps of;

i. determining if a version number value in said RTP header located in the payload of said identified UDP packet equals a predetermined value, and

ii determining if the packet length in said identified UDP packet header is within a predetermined range, and

if said determining substeps are affirmative, then characterizing said identified UDP packet as a candidate RTP packet of an RTP stream.

2. A method according to claim 1, wherein said identifying step comprises the further substep of:

iii. determining if a payload type value in said RTP header field located in the payload of said identified UDP packet is within a predetermined range.

3. A method according to claim 2 comprising the further steps of:

for each candidate RTP packet, determining from a source IP address, a destination IP address, a source UDP port, and a destination UDP port, associated with said identified UDP packet, if said candidate RTP packet is associated with a previously identified RTP stream or is associated with a newly identified RTP stream, and

for each candidate RTP packet associated with a newly identified RTP stream, storing said SSRC, sequence number and timestamp of said candidate RTP packet in association with said newly identified RTP stream.

4. A method according to claim 3 comprising the further steps of:

for each candidate RTP packet associated with a previously identified RTP stream, determining from said candidate RTP packet header;

SSRC, sequence number and timestamp,

comparing said determined SSRC, sequence number and timestamp with said stored SSRC, sequence number and timestamp of previously identified RTP streams, and

if there is a match in said comparison for one of said previously identified RTP streams, generating a signal associated with said candidate RTP packet denoting that said candidate RTP packet is a packet of said one previously identified RTP stream.

5. A method of detecting streams of packets on a network, each of said packets having a header and a payload, wherein said header includes a field for including a version number value representative of an RTP specification version number associated with said packet, a field for including a payload type value representative of a payload type associated with said packet, a field for including a sequence number value representative of a sequence number associated with said packet, and a field for including an SSRC value representative of a synchronization source associated with said packet, and wherein each of said packets has an associated size corresponding to the length of said packet, the method comprising the steps of:

receiving a plurality of packets of at least one stream;

detecting size of at least some of the received packets; and

detecting values of the header fields of the received packets; and

using the value of one or more of the header fields in combination with detected size, identifying one or more data streams on said network.

6. The method of claim 5, wherein the version number value is utilized in combination with the detected size to identify streams.

7. The method of claim 5, wherein the version number value and payload type value are utilized in combination with the detected size to identify streams.

8. The method of claim 5, wherein the version number value, the payload type value, the sequence number, and timestamp are utilized in combination with the detected size to identify streams.

9. The method of claim 5, comprising the further step of detecting packet spacing between the received packets and using the detected packet spacing in combination with the detected size and the header fields to identify streams.

10. The method of claim 5, wherein version number, payload type, sequence number value, the timestamp value, and the detected packet spacing are utilized in combination with the detected size to identify streams.

11. The method of claim 10, wherein the version number value, the payload type value, the sequence number value, the timestamp value, the detected packet spacing, and the SSRC number value are utilized in combination with the detected size to identify streams.

12. The method of claim 5, comprising the further step of:

for a detected stream, when the detected size of the packets is less than approximately 320 bytes, characterizing said stream as an audio data stream.

13. The method of claim 5, comprising the further step of:

for a detected stream, when the detected packets have a packet spacing in the approximate range 10 ms to 50 ms, characterizing said stream as an audio stream.

14. The method of claim 5, comprising the further step of:

for a detected stream, when the detected size of the packets is about 1500 bytes, characterizing said stream as a video stream.

15. The method of claim 5, comprising the further step of:

for a detected stream, when the detected packets have a packet spacing less than approximately 10 ms, characterizing said stream as a video stream.

16. The method of claim 5, further including the sub-step of:

determining the version number value.

17. The method according to claim 16, further including the sub-step of:

determining if a payload type value in said packet header field is within a predetermined range.

18. The method according to claim 17, further including the sub-step of:

determining if the sequence number value and the timestamp in said packet header field are consistent with the sequence number and timestamp of a packet previously identified on said network.

19. The method according to claim 18, further including the sub-step of:

determining if the temporal spacing of said packets relative to a packet previously identified on said network is within a predetermined range.

20. The method according to claim 19, further including the sub-step of:

determining if the SSRC value in said header of said packet matches the SSRC value of a packet previously identified on said network.

21. A system for identifying UDP packets on an IP network which are candidates for characterization as a packet of a Real Time Transport Protocol (RTP) stream, each of said UDP packets having a UDP header and a payload, wherein the payload potentially includes a RTP packet having a RTP header and a RTP payload, wherein said RTP header includes a field for including a version number value representative of an RTP specification version number associated with said RTP packet, a field for including a payload type value representative of a payload type associated with said RTP packet, a field for including a sequence number value representative of a sequence number associated with said RTP packet, and a field for including an SSRC value representative of a synchronization source associated with said RTP packet, and wherein each of said UDP packet headers includes a field for packet length corresponding to the size of said UDP packet, the system comprising:

an identification processor adapted to identify UDP packets at a point on said IP network, including characterization means operative on each identified UDP packet for;

i. determining if a version number value in said RTP header located in the payload of said identified UDP packet equals a predetermined value, and

ii determining if the packet length in said identified UDP packet header is within a predetermined range, and

if said determining substeps are affirmative, then characterizing said identified UDP packet as a candidate packet of an RTP stream.

22. A system according to claim 21, wherein said identification processor further comprises the means operative on each identified UDP packet for:

iii. determining if a payload type value in said RTP header located in the payload of said identified UDP packet is within a predetermined range.

23. A system according to claim 22 wherein said identification processor is adapted to:

for each candidate RTP packet, determine from a source IP address, a destination IP address, a source UDP port, and a destination UDP port of said identified UDP packet, associated with said candidate RTP packet, if said candidate RTP packet is associated with a previously identified RTP stream or is associated with a newly identified RTP stream, and

for each candidate RTP packet associated with a newly identified RTP stream, store said SSRC, sequence number and timestamp of said candidate RTP packet in association with said newly identified RTP stream.

24. A system according to claim 23 wherein said identification processor is adapted to:

for each candidate RTP packet associated with a previously identified RTP stream, determine from said candidate RTP packet header;

SSRC, sequence number and timestamp,

compare said determined SSRC, sequence number and timestamp with said stored SSRC, sequence number and timestamp of a previously identified RTP stream, and

if there is a match in said comparison for one of said previously identified RTP streams, generate a signal associated with said candidate RTP packet denoting that said candidate RTP packet is a packet of said one previously identified RTP stream.

25. A computer program product comprising instructions for identifying UDP packets on an IP network which are candidates for characterization as a packet of a Real Time Transport Protocol (RTP) stream, each of said UDP packets having a UDP header and a payload, wherein the payload potentially includes a RTP packet having a RTP header and a RTP payload, wherein said RTP header includes a field for including a version number value representative of an RTP specification version number associated with said RTP packet, a field for including a payload type value representative of a payload type associated with said RTP packet, a field for including a sequence number value representative of a sequence number associated with said RTP packet, and a field for including an SSRC value representative of a synchronization source associated with said RTP packet, and wherein each of said UDP packet headers includes a field for packet length corresponding to the size of said UDP packet, the product comprising instructions for:

identifying UDP packets at a point on said IP network, and for each identified UDP packet performing the substeps of;

i. determining if a version number value in said RTP header located in the payload of said identified UDP packet equals a predetermined value, and

ii determining if the packet length in said identified UDP packet header is within a predetermined range, and

if said determining substeps are affirmative, then characterizing said identified UDP packet as a candidate packet of an RTP stream.

26. A computer program product according to claim 25, wherein said computer program product further comprises instructions for:

iii. determining if a payload type value in said RTP header located in the payload of said identified UDP packet is within a predetermined range.

27. A computer program product according to claim 26 further comprising instructions for:

for each candidate RTP packet, determining from a source IP address, a destination IP address, a source UDP port, and a destination UDP port of said identified UDP packet, associated with said candidate RTP packet, if said candidate RTP packet is associated with a previously identified RTP stream or is associated with a newly identified RTP stream, and

for each candidate RTP packet associated with a newly identified RTP stream, storing said SSRC, sequence number and timestamp of said candidate RTP packet in association with said newly identified RTP stream.

28. A computer program product according to claim 27 further comprising instructions for:

for each candidate RTP packet associated with a previously identified RTP stream, determining from said candidate RTP packet header;

SSRC, sequence number and timestamp,

comparing said determined SSRC, sequence number and timestamp with said stored SSRC, sequence number and timestamp of a previously identified RTP stream, and

if there is a match in said comparison for one of said previously identified RTP streams, generating a signal associated with said candidate RTP packet denoting that said candidate RTP packet is a packet of said one previously identified RTP stream.