# US 10,484,163 B2 · Measure and improve clock synchronization using combination of transparent and boundary clocks > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,484,163 B2 - Document ID: US10484163B2 - Status: Granted - Kind: B2 - Application number: 15/782,915 - Filed: 2017-10-13 - Published: 2019-04-18 - Granted: 2019-11-19 - Earliest claimed: 2017-10-13 - Assignees: Cisco Technology, Inc. - Applicants: Cisco Technology, Inc. - Inventors: Anshul Tanwar; Vineet Kumar Garg; N V Hari Krishna N - Web page: https://patentgrep.com/patent/US10484163B2 ## CPC - H04L 7/0033: {Correction by delay} - 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)} - H04J 3/0673: {using intermediate nodes, e.g. modification of a received timestamp before further transmission to the next packet node, e.g. including internal delay time or residence time into the packet} - H04J 3/0641: {Change of the master or reference, e.g. take-over or failure of the master} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) ## Abstract The present technology improves synchronization of a slave node with a master node in a network using PTP packets in which the slave node is coupled to the working master node through at least one boundary node. The technology establishes a synchronization communication session between the boundary node and the slave node in which the synchronization communication session is configured to measure a first timing delay from the boundary node to the slave node, and establishes a transparent communication session between the master node and the slave node through the boundary timing node in which the transparent communication session configured to measure a second timing delay from the master node to the slave node. Using the sessions, the technology adjusts a timing delay correction factor according to the first timing delay and the second timing delay, and synchronizes the slave node with the master node according to the correction factor. ## Claims ### Claim 1 A network time synchronization management system comprising: a computing device in communication with a communication network comprising a slave node coupled to a working master node through at least one boundary node, the computing device comprising at least one non-transitory computer readable medium comprising instructions stored thereon that when executed are effective to cause at least one processor to: receive a request to synchronize the slave node with the working master node; establish a first communication session between the boundary node and the slave node, the first communication session configured to measure a first timing delay from the boundary node to the slave node; establish a second communication session between the working master node and the slave node through the boundary node, the second communication session configured to measure a second timing delay from the working master node to the slave node; adjust a timing delay correction factor according to the first timing delay and the second timing delay; and synchronize the slave node with the working master node according to the adjusted timing delay correction factor; wherein the first and second communications sessions are different from each other. ### Claim 2 (depends on 1) The network time synchronization management system of claim 1, wherein the instructions are further executed to display the adjusted timing delay correction factor on a display. ### Claim 3 (depends on 1) The network time synchronization management system of claim 1, wherein the request is received according to at least one of a manual request and at one of a plurality of automated requests issued at ongoing intervals. ### Claim 4 (depends on 1) The network time synchronization management system of claim 1, wherein the instructions are further executed to: identify a plurality of available master nodes in the communication network; establish the first and second communication sessions, adjust the timing delay correction factor, and synchronize the slave node on each of the available master nodes; and select one of the available master nodes to be the working master node based upon the adjusted timing delay correction factor determined for each available master node. ### Claim 5 (depends on 4) The network time synchronization management system of claim 4, wherein the instructions are further executed to receive the request from a plurality of slave nodes, wherein the slave nodes conduct an arbitration process to select one of the available master nodes to be the working master node. ### Claim 6 (depends on 5) The network time synchronization management system of claim 5, wherein the first and second communication sessions conform to an IEEE 1588 protocol, wherein the slave nodes are executed to conduct the arbitration process using a telemetry message conveyed among the slave nodes. ### Claim 7 (depends on 1) The network time synchronization management system of claim 1, wherein the request is received as a result of a trigger event from a communication channel through the slave node. ### Claim 8 A network time synchronization management method comprising: receiving, by at least one processor that executes instructions stored in at least one memory, a request to synchronize a slave node with a working master node, the slave node coupled to the working master node through at least one boundary node; establishing, using the instructions, a first communication session between the boundary node and the slave node, the first communication session configured to measure a first timing delay from the boundary node to the slave node; establishing, using the instructions, a second communication session between the working master node and the slave node through the boundary timing node, the second communication session configured to measure a second timing delay from the working master node to the slave node; adjusting, using the instructions, a timing delay correction factor according to the first timing delay and the second timing delay; and synchronizing, using the instructions, the slave node with the working master node according to the adjusted timing delay correction factor; wherein the first and second communications sessions are different from each other. ### Claim 9 (depends on 8) The network time synchronization management method of claim 8, further comprising receiving the request according to at least one of a manual request and one of a plurality of requests automatically issued at ongoing intervals. ### Claim 10 (depends on 8) The network time synchronization management method of claim 8, further comprising: identifying a plurality of available master nodes; establishing the first and second communication sessions, adjust the timing delay correction factor, and synchronize the slave node on each of the available master nodes; and selecting one of the available master nodes to be the working master node based upon the adjusted timing delay correction factor determined for each available master node. ### Claim 11 (depends on 10) The network time synchronization management method of claim 10, further comprising transmitting the request by a plurality of slave nodes, wherein the slave nodes conduct an arbitration process to select one of the available master nodes to be the working master node. ### Claim 12 (depends on 11) The network time synchronization management method of claim 11, further comprising conducting, by the slave nodes, the arbitration process using a telemetry message conveyed among the slave nodes, wherein the first and second communication sessions conform to an IEEE 1588 protocol. ### Claim 13 (depends on 8) The network time synchronization management method of claim 8, further comprising receiving the request as a result of a trigger event from a communication channel through the slave node. ### Claim 14 A computer-readable storage device storing instructions which, when executed by a processor, cause the processor to perform operations comprising: receiving a request to synchronize a slave node with a working master node, the slave node coupled to the working master node through at least one boundary node; establishing a first communication session between the boundary node and the slave node, the first communication session configured to measure a first timing delay from the boundary node to the slave node; establishing a second communication session between the working master node and the slave node through the boundary node, the second communication session configured to measure a second timing delay from the working master node to the slave node; adjusting a timing delay correction factor according to the first timing delay and the second timing delay; and synchronizing the slave node with the working master node according to the adjusted timing delay correction factor; wherein the first and second communications sessions are different from each other. ### Claim 15 (depends on 14) The instructions of claim 14, further comprising displaying the adjusted timing delay correction factor on a display. ### Claim 16 (depends on 14) The instructions of claim 14, further comprising receiving the request according to at least one of a manual request and at one of a plurality of automated requests issued at ongoing intervals. ### Claim 17 (depends on 14) The instructions of claim 14, further comprising: identifying a plurality of available master nodes in the communication network; establishing the first and second communication sessions, adjust the timing delay correction factor, and synchronize the slave node on each of the available master nodes; and selecting one of the available master nodes to be the working master node based upon the adjusted timing delay correction factor determined for each available master node. ### Claim 18 (depends on 17) The instructions of claim 17, further comprising transmitting the request by a plurality of slave nodes, wherein the slave nodes conduct an arbitration process to select one of the available master nodes to be the working master node. ### Claim 19 (depends on 18) The instructions of claim 18, further comprising conducting, by the slave nodes, the arbitration process using a telemetry message conveyed among the slave nodes, wherein the first and second communication sessions conform to an IEEE 1588 protocol. ### Claim 20 (depends on 14) The instructions of claim 14, further comprising receiving the request as a result of a trigger event from a communication channel through the slave node.