Media stream delay monitoring for node

• US 20030012136A1
• Filed: 07/12/2001
• Published: 01/16/2003
• Est. Priority Date: 07/12/2001
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Walles, Erik
• Granted Patent: US 7,035,210 B2
• Time in Patent Office: Days
• US Class Current: 370/229
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/5625 Operations, administration and maintenance [OAM]
• CPC Class Codes: H04L 2012/5649 Cell delay or jitter
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/283 in response to processing delays, e.g. caused by jitter or round trip time [RTT]
• CPC Class Codes: H04L 47/35 by embedding flow control information in regular packets, e.g. piggybacking
• CPC Class Codes: H04L 47/562 Attaching a time tag to queues
• CPC Class Codes: H04L 49/3081 ATM peripheral units, e.g. policing, insertion or extraction
• CPC Class Codes: H04L 49/90 Buffering arrangements

Abstract

A node (20, 20-2) of a packet switching network has a chain of processing units (30) through which a media stream of packets is routed for sequentially processing of each packet of the media stream. Each of the plural processing units of the chain generates an intra-node performance monitoring packet, and sends the intra-node performance monitoring packet to a performance monitoring unit (40) situated at the node. Each intra-node performance monitoring packet includes an indication of time spent by the packet of the media stream in the respective processing unit. The performance monitoring unit provides an indication of delay in the node for the media stream, e.g., the delay experienced at each processing unit of the chain and the overall delay for a packet of the media stream through the plural processing units comprising the processing chain of the node. For each processing unit, the intra-node performance monitoring packet can include plural components, such as a first component attributable to processing and a second component attributable to queuing delay. In case the delay experienced by the media stream packet between processing units of the node is not negligible, the performance monitoring unit acquires (e.g., estimates) a time required for the packet of the media stream to travel between successive processing units using a switch monitor packet. Each of the plural processing units can handle plural media streams, in different sequences if necessary. The performance monitoring unit is capable of providing an indication of delay in the node for each of the plural media streams.

Claims

1. A node of a packet switching network which handles a media stream of packets, the node comprising:

a processing chain comprising plural processing units through which a packet of the media stream is routed, each of the plural processing units generating an intra-node performance monitoring packet which includes an indication of time spent by the packet of the media stream in the respective processing unit;

a performance monitoring unit which receives the intra-node performance monitoring packets generated by the respective plural processing units and which uses contents of the intra-node performance monitoring packets to provide an indication of delay in the node for the media stream.

2. The node of claim 1, wherein the performance monitoring unit uses the contents of the intra-node performance monitoring packets to determine an overall delay of the packet of the media stream through the plural processing units of the node.

3. The node of claim 1, wherein at least one of the plural processing units has an associated queue, and wherein the intra-node performance monitoring packet generated by the at least one of the plural processing units with the associated queue includes a first component and a second component of the of the time spent by the packet of the media stream in the at least one of the plural processing units with the associated queue, the first component being a delay experienced by the packet of the media stream attributable to processing performed by the at least one processing units with the associated queue, the second component being a delay experienced by the packet of the media stream attributable to the associated queue.

4. The node of claim 1, wherein the performance monitoring unit acquires a time required for the packet of the media stream to travel between a first processing unit and a second processing unit.

5. The node of claim 4, wherein the performance monitoring unit estimates the time required for the packet of the media stream to travel between a first processing unit and a second processing unit with reference to an inter-unit delay monitor packet generated by the performance monitoring unit.

6. The node of claim 5, further comprising a switch which interconnects the processing units and the performance monitoring unit, wherein the inter-unit delay monitor packet is a switch-monitor packet, and wherein the performance monitoring unit determines a time required for the switch-monitoring packet to travel between the performance monitoring unit and a selected one of the plural processing units.

7. The node of claim 6, wherein the performance monitoring unit estimates the time required for the packet of the media stream to travel between a first processing unit and a second processing unit by determining an average transit time of the switch monitor packet between the selected one of the plural processing units and the performance monitoring unit.

8. The node of claim 1, wherein the performance monitoring unit estimates the time required for the packet of the media stream to travel between a first processing unit and a second processing unit by (1) determining a difference between an arrival time at the performance monitoring unit of an intra-node performance monitoring packet from the second processing unit and an arrival time at the performance monitoring unit of an intra-node performance monitoring packet from the first processing unit, and (2) adding a time delay in the first processing unit to the difference (1).

9. The node of claim 1, each of the plural processing units handles plural media streams, and wherein the performance monitoring unit provides an indication of delay in the node for each of the plural media streams.

11. The method of claim 9, further comprising using the contents of the intra-node performance monitoring packets to determine an overall delay of the packet of the media stream through the plural processing units of the node.

12. The method of claim 9, further comprising including in the intra-node performance monitoring packet a first component and a second component of the of the time spent by the packet of the media stream in the respective processing unit, the first component being a delay experienced by the packet of the media stream attributable to processing performed by respective processing unit, the second component being a delay experienced by the packet of the media stream attributable to a queue associated with the respective processing unit.

13. The method of claim 9, further comprising transmitting the intra-node performance monitoring packet from the respective processing unit to a performance monitoring unit through a switch.

14. The method of claim 9, further comprising acquiring a time required for the packet of the media stream to travel between a first processing unit and a second processing unit.

15. The method of claim 14, further comprising estimating the time required for the packet of the media stream to travel between a first processing unit and a second processing unit with reference to an inter-unit delay monitor packet generated by a performance monitoring unit of the node.

16. The method of claim 15, wherein the inter-unit delay monitor packet is a switch-monitor packet, and further comprising the performance monitoring unit determining a time required for the switch-monitoring packet to travel between the performance monitoring unit and a selected one of the plural processing units.

17. The method of claim 16, further comprising the performance monitoring unit estimating the time required for the packet of the media stream to travel between a first processing unit and a second processing unit by determining an average transit time of the switch monitor packet between the selected one of the plural processing units and the performance monitoring unit.

18. The method of claim 9, further comprising the performance monitoring unit estimating the time required for the packet of the media stream to travel between a first processing unit and a second processing unit by (1) determining a difference between an arrival time at the performance monitoring unit of an intra-node performance monitoring packet from the second processing unit and an arrival time at the performance monitoring unit of an intra-node performance monitoring packet from the first processing unit, and (2) adding a time delay in the first processing unit to the difference (1).

19. The method of claim 9, wherein each of the plural processing units handles plural media streams, and further comprising providing an indication of delay in the node for each of the plural media streams.

10. For use in a node of a packet switching network which handles a media stream of packets, a method comprising:

generating, at each of plural processing units comprising a processing chain through which a packet of the media stream is routed, an intra-node performance monitoring packet which includes an indication of time spent by the packet of the media stream in the respective processing unit;

using contents of the performance monitoring packets to provide an indication of delay in the node for the media stream.