# US 9,882,653 B2 · System and method of de-skewing electrical signals > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,882,653 B2 - Document ID: US9882653B2 - Status: Granted - Kind: B2 - Application number: 14/683,745 - Filed: 2015-04-10 - Published: 2016-10-13 - Granted: 2018-01-30 - Earliest claimed: 2015-04-10 - Assignees: Arista Networks, Inc. - Applicants: Arista Networks, Inc. - Inventors: Andrew Ahern Tamoney - Web page: https://patentgrep.com/patent/US9882653B2 ## CPC - H04B 10/6162: {Compensation of polarization related effects, e.g., PMD, PDL} - H04B 10/0799: {Monitoring line transmitter or line receiver equipment} - H04B 10/616: {Details of the electronic signal processing in coherent optical receivers} - H04J 14/02: Wavelength-division multiplex systems - H04L 1/243: {at the transmitter, using a loop-back} - H04L 25/14: Channel dividing arrangements {, i.e. in which a single bit stream is divided between several baseband channels and reassembled at the receiver} - H04B 10/07: Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems - H04B 10/50: Transmitters - H04B 10/60: Receivers - H04B: TRANSMISSION - 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) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A method and apparatus of a device that determines transmit and receive skew times between pairs of lanes of an electrical interface of a network element is described. In an exemplary embodiment, the device receive a plurality of configurations corresponding to a plurality of electrical loopbacks that can each couple transmit and receive interfaces of the electrical interface via the plurality of lanes in different patterns. In addition, for each of the plurality of electrical loopbacks, the device couples this electrical loopback to the transmit and receive interfaces of the electrical interface and measures overall skew times for pairs of the plurality of lanes of the electrical interface. Furthermore, the device computes the transmit and receive skew times for the transmit and receive interfaces from the overall skew times. ## Claims ### Claim 1 A non-transitory machine-readable medium having executable instructions to cause one or more processing units to perform a method for determining transmit and receive skew times between pairs of a plurality of lanes of an electrical interface of a network element, the method comprising: receiving a plurality of configurations corresponding to a plurality of electrical loopbacks that each couple to transmit and receive interfaces of the electrical interface via the plurality of lanes in different coupling patterns; for each of the plurality of electrical loopbacks, coupling an electrical loopback to the transmit and receive interfaces of the electrical interface, and measuring overall skew times for the pairs of the plurality of lanes of the electrical interface; and computing the transmit and receive skew times for the transmit and receive interfaces from the overall skew times. ### Claim 2 (depends on 1) The non-transitory machine-readable medium of claim 1, wherein each of the plurality of lanes represents a different polarization and quadrature combination. ### Claim 3 (depends on 1) The non-transitory machine-readable medium of claim 1, further comprising: de-skewing the electrical interface with the transmit and receive skew times. ### Claim 4 (depends on 1) The non-transitory machine-readable medium of claim 1, wherein the transmit and receive interfaces are physical interfaces. ### Claim 5 (depends on 1) The non-transitory machine-readable medium of claim 1, wherein one of the plurality of configurations is a straight-line electrical loopback. ### Claim 6 (depends on 1) The non-transitory machine-readable medium of claim 1, wherein one of the plurality of configurations is a twisted electrical loopback. ### Claim 7 (depends on 1) The non-transitory machine-readable medium of claim 1, wherein the plurality of lanes includes four lanes and the plurality of configurations is three different configurations. ### Claim 8 (depends on 1) The non-transitory machine-readable medium of claim 1, wherein each of the plurality of lanes carries a different electrical pulse that is used to transport a coherent optical signal. ### Claim 9 (depends on 1) The non-transitory machine-readable medium of claim 1, further comprising: checking the transmit and receive skew times by using an electrical loopback that has a different configuration than the plurality of configurations used to compute the transmit and receive skew times. ### Claim 10 A method for determining transmit and receive skew times between pairs of a plurality of lanes of an electrical interface of a network element, the method comprising: receiving a plurality of configurations corresponding to a plurality of electrical loopbacks that each couple to transmit and receive interfaces of the electrical interface via the plurality of lanes in different coupling patterns; for each of the plurality of electrical loopbacks, coupling an electrical loopback to the transmit and receive interfaces of the electrical interface, and measuring overall skew times for the pairs of the plurality of lanes of the electrical interface; and computing the transmit and receive skew times for the transmit and receive interfaces from the overall skew times. ### Claim 11 (depends on 10) The method of claim 10, wherein each of the plurality of lanes represents a different polarization and quadrature combination. ### Claim 12 (depends on 11) The method of claim 11, further comprising: de-skewing the electrical interface with the transmit and receive skew times. ### Claim 13 (depends on 10) The method of claim 10, wherein the transmit and receive interfaces are physical interfaces. ### Claim 14 (depends on 10) The method of claim 10, wherein one of the plurality of configurations is a straight-line electrical loopback. ### Claim 15 (depends on 10) The method of claim 10, wherein one of the plurality of configurations is a twisted electrical loopback. ### Claim 16 (depends on 10) The method of claim 10, wherein the plurality of lanes includes four lanes and the plurality of configurations is three different configurations. ### Claim 17 (depends on 10) The method of claim 10, wherein each of the plurality of lanes carries a different electrical pulse that is used to transport a coherent optical signal. ### Claim 18 (depends on 10) The method of claim 10, further comprising: checking the transmit and receive skew times by using an electrical loopback that has a different configuration than the plurality of configurations used to compute the transmit and receive skew times. ### Claim 19 A device for determining transmit and receive skew times between pairs of a plurality of lanes of an electrical interface of a network element, the device comprising: a memory for storing instructions; and a processing circuit that executes the instructions stored in the memory, which causes the processing circuit to receive a plurality of configurations corresponding to a plurality of electrical loopbacks that each couple to transmit and receive interfaces of the electrical interface via the plurality of lanes in different coupling patterns, for each of the plurality of electrical loopbacks, couple an electrical loopback to the transmit and receive interfaces of the electrical interface; and measure overall skew times for the pairs of the plurality of lanes of the electrical interface, and compute the transmit and receive skew times for the transmit and receive interfaces from the overall skew times. ### Claim 20 (depends on 19) The device of claim 19, wherein each of the plurality of lanes represents a different polarization and quadrature combination.