Multi-frame network clock synchronization
First Claim
1. A network component comprising:
- a processor configured to;
transmit a first frame comprising an Open System Interconnection (OSI) layer two header and a payload to a downstream node, wherein the first frame'"'"'s OSI layer two header comprises a first timestamp indicating a transmission time of the first frame according to a first clock associated with the network component; and
receive a second frame comprising an OSI layer two header and a payload at a reception time according to the first clock, wherein the second frame'"'"'s OSI layer two header comprises a second timestamp that indicates an internal processing delay associated with the downstream node and a frame count timestamp that differentiates the second frame from the first frame,wherein a second clock is associated with the downstream node,wherein the first clock and the second clock are synchronized using the first timestamp, the second timestamp, or both,wherein the first clock comprises a first localized clock source positioned within the network component, wherein the second clock comprises a second localized clock source positioned within the downstream node,wherein the frame count timestamp indicates a number of synchronization window periods, andwherein the first localized clock source and the second localized clock source are generated independently from one another.
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Abstract
A network component comprising a processor configured to implement a method comprising promoting transmission of a first frame comprising a first timestamp associated with a transmission time of the first frame, recognizing a reception of a second frame having a reception time, wherein the second frame comprises a second timestamp comprising a downstream node delay associated with a downstream node, measuring a total delay between the transmission time of the first frame and the reception time of the second frame, and calculating a transport delay using the total delay and the downstream node delay. Also disclosed is a clock synchronization method comprising receiving a first frame comprising a first timestamp associated with an upstream clock at a reception time, sending a second frame at a transmission time, and measuring a downstream node delay between the reception time and the transmission time, wherein the second frame comprises the downstream node delay.
148 Citations
20 Claims
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1. A network component comprising:
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a processor configured to; transmit a first frame comprising an Open System Interconnection (OSI) layer two header and a payload to a downstream node, wherein the first frame'"'"'s OSI layer two header comprises a first timestamp indicating a transmission time of the first frame according to a first clock associated with the network component; and receive a second frame comprising an OSI layer two header and a payload at a reception time according to the first clock, wherein the second frame'"'"'s OSI layer two header comprises a second timestamp that indicates an internal processing delay associated with the downstream node and a frame count timestamp that differentiates the second frame from the first frame, wherein a second clock is associated with the downstream node, wherein the first clock and the second clock are synchronized using the first timestamp, the second timestamp, or both, wherein the first clock comprises a first localized clock source positioned within the network component, wherein the second clock comprises a second localized clock source positioned within the downstream node, wherein the frame count timestamp indicates a number of synchronization window periods, and wherein the first localized clock source and the second localized clock source are generated independently from one another. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A clock synchronization method comprising:
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receiving, by a downstream node, a first frame comprising an Open System Interconnection (OSI) layer two header and a payload at a reception time according to a downstream clock, wherein the first frame'"'"'s OSI layer two header comprises a first timestamp associated with an upstream clock; sending, by the downstream node, a second frame comprising an OSI layer two header and a payload at a transmission time according to the downstream clock, wherein the second frame'"'"'s OSI layer two header comprises the first timestamp, a second timestamp, and a frame count timestamp that identifies the second frame; determining an internal processing delay of the downstream node according to a difference between the reception time and the transmission time, wherein the second timestamp indicates the internal processing delay; and synchronizing the upstream clock and the downstream clock using the first timestamp and the second timestamp, wherein the upstream clock corresponds to an upstream node, wherein the downstream clock corresponds to the downstream node, and wherein the frame count timestamp provides a count of synchronization window periods. - View Dependent Claims (12, 13, 14)
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15. A system comprising:
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a first node comprising a first clock, the first node configured to;
transmit a first packet comprising an Open System Interconnection (OSI) layer two header and a payload, wherein the first packet'"'"'s OSI layer two header comprises a first timestamp associated with the first clock; anda second node comprising a second clock, the second node configured to; receive the first packet; and send a second packet comprising an OSI layer two header and a payload to the first node, wherein the second packet'"'"'s OSI layer two header comprises the first timestamp, a first frame count timestamp corresponding to the first packet, and a second timestamp corresponding to the second clock, wherein the first frame count timestamp indicates a first count of synchronization windows that have occurred when the first packet is transmitted by the first node, and wherein the first node uses the first timestamp, the first frame count timestamp, and the second timestamp to synchronize the first clock with the second clock. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification