Method, a computer program product, and a carrier for indicating one-way latency in a data network

• US 10,425,309 B2
• Filed: 07/04/2018
• Issued: 09/24/2019
• Est. Priority Date: 09/22/2004
• Status: Active Grant

• Current Assignee: Accedian Networks Inc. (Cisco Systems, Inc.)
• Original Assignee: Accedian Networks Inc. (Cisco Systems, Inc.)
• Inventors: Hansson, Kjell, Hagsand, Olof
• Primary Examiner(s): Onamuti, Gbemileke J
• Application Number:
  US16/027,335
• Publication Number:
  US 20180316586A1
• Time in Patent Office: 447 Days
• CPC Class Codes: G06F 1/12 Synchronisation of different clock signals provided by a plurality of clock generators
• CPC Class Codes: H04J 3/0638 Clock or time synchronisation among nodes; Internode synchronisation synchronization for ring networks H04L12/422; data switching networks with synchronous transmission H04L12/43
• CPC Class Codes: H04J 3/0667 Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays arrangements for monitoring round trip delays in packet switching networks H04L43/0864
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
• CPC Class Codes: H04L 2212/00 Encapsulation of packets
• CPC Class Codes: H04L 43/067 using time frame reporting
• CPC Class Codes: H04L 43/0852 Delays
• CPC Class Codes: H04L 43/0858 One way delays
• 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 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• CPC Class Codes: H04L 7/10 Arrangements for initial synchronisation

Abstract

Disclosed herein is a method, a computer program product, and a carrier for indicating one-way latency in a data network (N) between a first node (A) and a second node (B), wherein the data network (N) lacks continuous clock synchronization, comprising: a pre-synchronization step, a measuring step, a post-synchronization step, an interpolation step, and generating a latency profile. The present invention also relates to a computer program product incorporating the method, a carrier comprising the computer program product, and a method for indicating server functionality based on the first aspect.

Claims

1. A system to determine a one-way latency between nodes in a network, comprising:

a first node, wherein the first node is configured to send a first message and determine a first value indicative of a time the first message is sent, and wherein the first node is configured to receive a second message and determine a second value indicative of a time the second message is received;

a second node, wherein the second node is configured to receive the first message from the first node and determine a third value indicative of a time the first message is received, and wherein the second node is configured to send the second message to the first node and determine a fourth value of a time the second message is sent;

a first clock, wherein the first clock determines the first value and the second value; and

a second clock, wherein the second clock determines the third value and the fourth value;

wherein the first node configured to generating the one-way latency profile based on a combination of the first value, the second value, the third value, and the fourth value;

wherein the first clock and the second clock are not synchronized and are linear with respect to each other over a period required to determine the one-way latency.

2. A method for determining a one-way latency between nodes in a network, the method comprising:

measuring during a first time period, a first offset between a first clock utilized by a first node and a second clock utilized by a second node;

measuring during a second time period, a one way delay between transmission of a message from the first node to reception of the message at the second node;

measuring during a third time period, a third offset between the first clock utilized by the first node and the second clock utilized by the second node, the first time period being prior to the second time period, the second time period being prior to the third time period;

utilizing the first offset and the third offset to calculate a second offset between the first clock and the second clock during the second time period; and

calculating, utilizing the second offset, an adjusted one way delay of the message.

3. The method of claim 2 wherein the calculation of the second offset utilizes a rate of change of a time difference between the first clock and the second clock over a period between the first time period and the third time period.

4. The method of claim 3 wherein the rate of change is linear.

5. The method of claim 2 wherein the first offset comprises a minimum round trip delay of a plurality of messages transmitted between the first node and the second node during the first time period.

6. The method of claim 2 wherein the third offset comprises a minimum round trip delay of a plurality of messages transmitted between the first node and the second node during the third time period.

7. The method of claim 2 wherein the second offset further comprises an estimation of an internal delay within the first node.

8. The method of claim 2 wherein the second offset further comprises an estimation of an internal delay within the second node.