Quasi RTP metrics for non-RTP media flows

• US 7,817,546 B2
• Filed: 07/06/2007
• Issued: 10/19/2010
• Est. Priority Date: 07/06/2007
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Bryant, Stewart Frederick, Oran, David R., Filsfils, Clarence, Bettink, John H. W.
• Primary Examiner(s): Pham; Chi H.
• Assistant Examiner(s): Hom; Shick
• Application Number:
  US11/774,343
• Publication Number:
  US 20090010158A1
• Time in Patent Office: 1,201 Days
• Field of Search: None
• US Class Current: 370/231
• CPC Class Codes: H04L 41/0816 the condition being an adaptation, e.g. in response to network events
• CPC Class Codes: H04L 43/026 using flow identification
• CPC Class Codes: H04L 43/0829 Packet loss
• CPC Class Codes: H04L 43/0852 Delays
• CPC Class Codes: H04L 43/087 Jitter
• CPC Class Codes: H04L 43/106 using time related information in packets, e.g. by adding timestamps
• 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
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

In one embodiment, a router receives a real-time multimedia flow that comprises IP packets. The router then processes values included in the Identifier fields of the IP packets using resources similar to those used in the monitoring of RTP flows to identify metrics for the real-time multimedia flow. The metrics may be transferred to a remote management device for aggregation with metrics output by other routers located on the data path for the real-time multimedia flow.

Claims

1. A method, comprising:

receiving an input indicating how a remote network device populates fields designated to be accessed during fragmentation and reassembly, wherein the fields are fragmentation fields of Internet Protocol (IP) headers;

receiving a flow of packets that are transferred by the remote network device and that include the IP headers with the populated fragmentation fields;

determining whether the flow of packets requests no fragmentation;

only when the flow of packets requests no fragmentation, analyzing different values included in the fragmentation fields of the IP headers to identify metrics for the received flow of packets; and

outputting the metrics for the received flow of packets.

2. The method of claim 1, further comprising:

wherein the different values are each sixteen-bit values; and

processing the sixteen-bit values using one or more Real-Time Protocol (RTP) metrics algorithms to identify the metrics for the received flow that is a non-RTP flow.

3. The method of claim 1, further comprising overwriting unique identifiers included in the fragmentation fields of the IP headers with the different values before forwarding the flow of packets towards a destination endpoint.

4. The method of claim 3, wherein the different values comprise sequence numbers.

5. A method, comprising:

identifying packet fields for specifying unique identifiers initially designated for use during correlation and reassembly of fragmented messages, wherein the fields are fragmentation fields of IP headers;

determining whether the packets request no fragmentation;

only when the packets request no fragmentation, formatting the identified packet fragmentation fields of the IP headers with different values before forwarding packets having the packet fragmentation fields; and

analyzing the different values of the packet fragmentation fields of the IP headers after the packets are forwarded to identify lost ones of the forwarded packets.

6. The method of claim 5, further comprising replacing unique identifiers included in the identified packet fragmentation fields of the IP headers with the different values at a forwarding device located remotely with respect to a transmitting source that formats the fragmentation fields of the IP headers with the unique identifiers.

7. The method of claim 5, further comprising replacing fragmentation offset values included in the packets with timestamp values at an intermediary device located on a data path for the packets.

8. The method of claim 7, further comprising replacing the timestamp values with zero values before the packets are received on a destination endpoint.

9. The method of claim 8, further comprising determining latency information for the packets according to the inserted timestamp values.

10. An apparatus, comprising:

one or more processors; and

a memory coupled to the processors comprising instructions executable by the processors, the processors operable when executing the instructions to;

receive a stream of packets sent using a protocol that supports fragmentation, the packets including fields designated by the protocol for use during packet fragmentation and packet reassembly;

identify a pattern used for selecting different values to include into the fields; and

only when a ‘

do not fragment’

bit is set in the packets, analyze the different values included in the fields according to the identified pattern to measure packet loss for the stream.

11. The apparatus of claim 10, wherein the protocol is the Internet Protocol (IP) and the fields are sixteen-bit identifier fields.

12. The apparatus of claim 10, wherein the processors are further operable to analyze the different values included in the fields only when the identified pattern is a monotonically increasing selection pattern.

13. The apparatus of claim 10, wherein the processors are further operable to identify the pattern according to a pre-configuring input specifying that a source endpoint for the stream of packets uses the identified pattern.

14. The apparatus of claim 10, wherein the processors are further operable to identify the pattern during a signaling exchange with a remote forwarding device that is located on a data path for the stream of packets and that reformats the fields using monotonically increasing sixteen-bit values.

15. The apparatus of claim 10, wherein the processors are operable to output a communication that identifies the packet loss for accumulation with loss metrics output by remote network devices located on a data path for the stream of packets.

16. The apparatus of claim 10, further comprising:

an RTP metrics calculation engine;

wherein the processors are further operable to feed the different values into the RTP metrics calculation engine when the protocol is the Internet Protocol (IP).

17. The apparatus of claim 10, wherein the processors are further operable to analyze the different values to determine the packet loss when a setting included in a local memory or received signaling requests flow monitoring for the stream.

18. An apparatus, comprising:

one or more processors; and

a memory coupled to the processors comprising instructions executable by the processors, the processors operable when executing the instructions to;

receive a stream of packets sent using a protocol that supports fragmentation, the packets including fields designated by the protocol for use during packet fragmentation and packet reassembly;

determine whether the stream of packets requests no fragmentation; and

only when the stream of packets requests no fragmentation, format the fields that are designated by the protocol for use during packet fragmentation and packet reassembly with timestamp values before forwarding the stream of packets.

19. The apparatus of claim 18, wherein the processors are further operable to forward the stream of packets without formatting the fields when the stream of packets does not request no fragmentation.

20. The apparatus of claim 18, wherein the apparatus inserts the timestamp values in an ordering that allows a remote network device to measure latency for the stream of packets by reading the fields designated by the protocol for use during packet fragmentation and packet reassembly.

21. The apparatus of claim 18, wherein the timestamp values correspond to a subset of bits from Network Time Protocol (NTP) timestamps.

22. The apparatus of claim 21, wherein the fields are thirteen bit fields and the subsets of bits correspond to a range including the thirty-first and forty-third bits of the NTP timestamps.