Granted Patent B2

US 8,804,762 · App. 12/640,497 · Granted Aug 12, 2014

Abstract

Claims (42)

1. A method for time-stamping a data frame, the data frame including a type field and data for transmission to a communication network, the method comprising:

receiving the data frame;

determining a reception time for the data frame;

determining a value of the type field, the type field indicating whether the data frame is a time-stamped frame;

responsive to determining that the value of the type field indicates the data frame is a time-stamped frame;

calculating a length value, the length value indicating a length from an end of a length field to a start of a time stamp field, the length value including a length of the type field and a length of a data payload field containing the data, the length value indicating the position of the timestamp field;

inserting the length field in the data frame prior to the data and prior to the type field, the length field including the length value; and

inserting the timestamp field at a position in the data frame after the length field, the timestamp field, the timestamp field indicating the reception time.

2. The method of claim 1 , wherein the data frame is an Ethernet data frame.

3. The method of claim 2 , wherein the timestamp field is positioned immediately following the data.

4. The method of claim 2 , further comprising transmitting the Ethernet data frame to the communication network.

5. The method of claim 2 , further comprising inserting a header tag in the Ethernet data frame, the header tag including at least a timestamp type.

6. The method of claim 2 , wherein the Ethernet data frame is received at a reconciliation sublayer.

7. The method of claim 2 , further comprising responsive to determining that the Ethernet data frame is not a time-stamped frame, ignoring the reception time.

8. An apparatus for time-stamping an Ethernet data frame, the Ethernet data frame including a type field and data for transmission to a communication network, the apparatus comprising:

a reconciliation sublayer configured to receive the Ethernet data frame;

a real time clock configured to determine a reception time for the Ethernet data frame; and

a start frame delimiter detector communicatively coupled to the reconciliation sublayer and the real time clock, the start frame delimiter detector configured to:

determine a value of the type field, the type field indicating whether the data frame is a time-stamped frame; and

responsive to determining that the value of the type field indicates the data frame is a time-stamped frame:

calculate a length value, the length value indicating a length from an end of a length field to a start of a timestamp field, the length value including a length of the type field and a length of a data payload field containing the data, the length value indicating the position of the timestamp field;

insert the length field in the Ethernet data frame immediately prior to the type field, the length field including the length value; and

insert the timestamp field at a position in the Ethernet data frame after the length field, the timestamp field indicating the reception time.

9. The apparatus of claim 8 , wherein the timestamp field is positioned immediately following the data.

10. The apparatus of claim 8 , further comprising a communication interface configured to transmit the Ethernet data frame to the communication network.

11. The apparatus of claim 8 , further comprising a Media Access Control (“MAC”) sublayer in communication with the reconciliation sublayer and the start frame delimiter detector, the MAC sublayer configured to insert a header tag in the Ethernet data frame, the header tag including at least a timestamp type and a length field.

12. The apparatus of claim 8 , wherein responsive to determining that the Ethernet data frame is not a time-stamped frame, the start frame delimiter detector is further configured to ignore the reception time.

13. A system for time-stamping an Ethernet data frame, the Ethernet data frame including data for transmission, the system comprising:

a routing controller configured to:

receive the Ethernet data frame, the Ethernet data frame having a type field;

determine a reception time for the Ethernet data frame;

determine a value of the type field, the type field indicating whether the data frame is a time-stamped frame; and

responsive to determining that the value of the type field indicates the data frame is a time-stamped frame:

calculate a length value, the length value indicating a length from an end of a length field to a start of a timestamp field, the length value including a length of the type field and a length of a data payload field containing the data, the length value indicating the position of the timestamp field;

insert the length field in the Ethernet data frame immediately prior to the type field, the length field including the length value; and

insert the timestamp field at a position in the Ethernet data frame after the length field, the timestamp field indicating the reception time.

14. The system of claim 13 , wherein the timestamp field is positioned immediately following the data.

15. The system of claim 13 , further comprising a communication interface in communication with the routing controller, the communication interface configured to transmit the Ethernet data frame.

16. The system of claim 13 , wherein the routing controller includes:

a reconciliation sublayer configured to receive the Ethernet data frame; and

a Media Access Control (“MAC”) configured to insert a header tag in the Ethernet data frame, the header tag including at least a timestamp type and a length field.

17. The system of claim 13 , wherein responsive to determining that the Ethernet data frame is not a time-stamped frame, the routing controller is further configured to ignore the reception time.

Assignments (21)