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US 2022/0069970 A1Published application
Time transfer using passive tapping
AssigneeArista Networks, Inc.
InventorsDavid C.A. Snowdon, David J. Mirabito
Life of this patent
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Abstract
Techniques for determining a clock offset between monitoring devices in a network. Such techniques include: obtaining, by a first monitoring device, a first set of network traffic data units sent between a first endpoint and a second endpoint via a first tap on a network link between the first endpoint and second endpoint; obtaining, by a second monitoring device, a second set of network traffic data units sent between the first endpoint and the second endpoint via a second tap on the network link; calculating the clock offset between the first monitoring device and the second monitoring device using the first set of network traffic data units and the second set of network traffic data units; and performing an offset action based on the clock offset.
Claims20
A method for determining an offset between clocks in a network, the method comprising:
- tapping, by a first monitoring device, a first interface of a first endpoint that is operatively connected to a second interface of a second endpoint;
- tapping, by a second monitoring device, the second interface;
- receiving, at the first monitoring device and from the first interface, a first network traffic data unit;
- creating, by the first monitoring device, a first unique identifier using the first network traffic data unit;
- storing, by the first monitoring device;
- the first unique identifier and a first timestamp indicating a first time at which the first monitoring device received the first network traffic data unit, wherein the first unique identifier and the first timestamp from a first associated information item;
- transmitting, from the first monitoring device to the second monitoring device, the first associated information item;
- receiving, at the second monitoring device and from the second interface, the first network traffic data unit;
- creating, by the second monitoring device, the first unique identifier using the first network traffic data unit;
- storing, by the second monitoring device;
- the first unique identifier and a second timestamp indicating a second time at which the second monitoring device received the first network traffic data unit, wherein the first unique identifier and the second timestamp from a second associated information item;
- transmitting, from the second monitoring device to the first monitoring device, the second associated information item;
- receiving, at the second monitoring device and from the second interface, a second network traffic data unit;
- creating, by the second monitoring device, a second unique identifier using the second network traffic data unit;
- storing, by the second monitoring device;
- the second unique identifier and a third timestamp indicating a third time at which the second monitoring device received the second network traffic data unit, wherein the second unique identifier and the third timestamp from a third associated information item;
- transmitting, from the second monitoring device to the first monitoring device, the third associated information item;
- receiving, at the first monitoring device and from the first interface, the second network traffic data unit;
- creating, by the first monitoring device, the second unique identifier using the second network traffic data unit;
- storing, by the first monitoring device;
- the second unique identifier and a fourth timestamp indicating a fourth time at which the first monitoring device received the second network traffic data unit, wherein the second unique identifier and the fourth timestamp from a fourth associated information item;
- transmitting, from the first monitoring device to the second monitoring device, the fourth associated information item;
- and
- performing a calculation using the first associated information item, the second associated information item, the third associated information item, and the fourth associated information item, to determine a time offset between the first monitoring device and the second monitoring device.
21 more elements
A monitoring device for determining a clock offset between monitoring devices in a network, the monitoring device comprising:
- a clock device comprising circuitry and configured to measure time;
- a timestamp device, comprising circuitry, operatively connected to the clock device, and configured to:
- generate a first timestamp corresponding to receipt, from a first endpoint, of a first network traffic data unit at the monitoring device using the clock device;
- and
- generate a second timestamp corresponding to receipt of a second network traffic data unit, from a second endpoint, at the monitoring device using the clock device;
- a unique identifier device comprising circuitry and configured to:
- generate a first unique identifier associated with the first network traffic data unit;
- and
- generate a second unique identifier associated with the second network traffic data unit;
- wherein the monitoring device is configured to:
- generate a first associated information item comprising the first timestamp and the first unique identifier;
- generate a second associated information item comprising the second timestamp and the second unique identifier;
- receive a third associated information item from a second monitor device associated with the receipt of the first network traffic data unit at the second endpoint, the third associated information item comprising a third timestamp and the first unique identifier;
- receive a fourth associated information item from the second monitor device associated with the sending of the second network traffic data unit from the second endpoint, the fourth associated information item comprising a fourth timestamp and the second unique identifier;
- and
- an offset calculation device, comprising circuitry, and configured to:
- calculate the clock offset between the first monitoring device and the second monitoring device using the first associated information item, the second associated information item, the third associated information item, and the fourth associated information item;
- and
- perform an offset action based on the clock offset.
16 more elements
A method for determining a clock offset between monitoring devices in a network, the method comprising:
- obtaining, by a first monitoring device, a first set of network traffic data units sent between a first endpoint and a second endpoint via a first tap on a network link between the first endpoint and second endpoint;
- obtaining, by a second monitoring device, a second set of network traffic data units sent between the first endpoint and the second endpoint via a second tap on the network link;
- calculating the clock offset between the first monitoring device and the second monitoring device using the first set of network traffic data units and the second set of network traffic data units;
- and
- performing an offset action based on the clock offset.
2 more elements
Dependencies are inferred from the claim text.