One-step timestamping in network devices
A physical layer (PHY) processor of a network device receives: a timing packet that includes initial timing information, and one or more indicators of one or more parameters to be used by the PHY processor for embedding timing information into the timing packet, the one or more indicators including at least i) an indicator indicating that the timing packet is a type of packet into which timing information is to be embedded by the PHY device, ii) an indicator of a location of a field in the timing packet at which the timing information is to be embedded into the timing packet by the PHY device, and iii) an indicator of whether timing information in the timing packet needs to be updated by the PHY device. The PHY processor updates, based on the one or more indicators, the initial timing information in the timing packet.
1. A method for processing timing packets for synchronization in a network device, the method comprising:
receiving, at a media access control (MAC) processor of the network device, a timing packet to be transmitted by the network device;
performing initial processing of the timing packet by the MAC processor, including generating a plurality of indicators of parameters to be used by a PHY device of the network device for embedding timing information into the timing packet, the plurality of indicators including at least i) a packet type indicator indicating that the timing packet is a type of packet into which timing information is to be embedded by the PHY device, ii) a location indicator indicating a location of a field in the timing packet at which the timing information is to be embedded into the timing packet by the PHY device, and iii) a wraparound indicator indicating whether a wraparound of a value of the field is to be accounted for by the PHY device; and
transferring i) the timing packet and ii) the plurality of indicators from the MAC processor to the PHY device for further processing of the timing packet based on the plurality of indicators and subsequent transmission of the timing packet from the network device.
2. The method of claim 1 , further comprising:
generating, by the MAC processor, a control header to include the plurality of indicators generated for the timing packet; and
inserting, by the MAC processor, the control header into the timing packet prior to transferring the timing packet to the PHY device.
3. The method of claim 2 , further comprising:
generating, by the MAC processor, a PHY tag to be included in the control header, including generating the PHY tag to include one or more indicator among the plurality of indicators;
generating, by the MAC processor, the control header to include the PHY tag in an extension field of the control header; and
inserting the control header at a predetermined location within the timing packet prior to transferring the timing packet to the PHY device.
4. The method of claim 3 , wherein inserting the control header at the predetermined location in the timing packet comprises replacing, with the control header, a preamble at a beginning of the timing packet.
5. The method of claim 4 , wherein generating the PHY tag includes generating the PHY tag to include one or both of the location indicator and the wraparound indicator.
6. The method of claim 5 , generating the PHY tag includes generating the PHY tag to further include a checksum update indicator indicating whether a checksum update is needed for the timing packet.
7. The method of claim 1 , wherein receiving the timing packet comprises receiving one of i) a timing packet generated by a host processor of the network device, the timing packet including a correction field into which the PHY device is to embed the timing information or ii) a timing packet previously received by the network device, the timing packet previously received by the network device including a correction field to be used for indicating a residence time of the timing packet in the network device.
8. A network device configured to operate in a network, the network device comprising:
a media access control (MAC) processor configured to:
receive a timing packet to be transmitted by the network device,
generate a plurality of indicators of parameters to be used by a PHY device of the network device for embedding timing information into the timing packet, the plurality of indicators including at least i) a packet type indicator indicating that the timing packet is a type of packet into which timing information is to be embedded by the PHY device, ii) a location indicator indicating a location of a field in the timing packet at which the timing information is to be embedded into the timing packet by the PHY device, and iii) a wraparound indicator indicating whether a wraparound of a value of the field is to be accounted for by the PHY device, and
transfer i) the timing packet and ii) the plurality of indicators to the PHY device for further processing of the timing packet based on the plurality of indicators and subsequent transmission of the timing packet from the network device.
9. The network device of claim 8 , wherein the MAC processor is further configured to:
generate a control header to include the plurality of indicators; and
insert the control header into the timing packet prior to transferring the timing packet to the PHY device.
10. The network device of claim 9 , wherein the MAC processor is further configured to:
generate a PHY tag to be included in the control header;
generate the control header to include the PHY tag in an extension field of the control header; and
insert the control header at a predetermined location within the timing packet prior to transferring the timing packet to the PHY device.
11. The network device of claim 10 , wherein the MAC processor is configured to replace, with the control header, a preamble at a beginning of the timing packet.
12. The network device of claim 10 , wherein the MAC processor is configured to generate the PHY tag to include one or both of the location indicator and the wraparound indicator.
13. The network device of claim 12 , wherein the MAC processor is configured to generate the PHY tag to further include a checksum update indicator indicating whether a checksum update is needed for the timing packet.
14. The network device of claim 8 , wherein:
the timing packet is one of i) a timing packet generated by a host processor of the network device, the timing packet including a correction field into which the PHY device is to embed the timing information or ii) a timing packet previously received by the network device, the timing packet previously received by the network device including a correction field to be used for indicating a residence time of the timing packet in the network device.
15. The network device of claim 8 , wherein the timing information to be embedded in the timing packet indicates one of i) a time corresponding to transmission of the timing packet from the network device or ii) a residence time of the timing packet in the network device.
16. A network device configured to operate in a network, the network device comprising:
a media access control (MAC) processor coupled to a physical layer (PHY) device, wherein the MAC processor is configured to:
receive a timing packet to be transmitted by the network device,
generate a plurality of indicators of parameters to be used by a PHY device of the network device for embedding timing information into the timing packet, the plurality of indicators including at least i) a packet type indicator indicating that the timing packet is a type of packet into which timing information is to be embedded by the PHY device, ii) a location indicator indicating a location of a field in the timing packet at which the timing information is to be embedded into the timing packet by the PHY device, and iii) a wraparound indicator indicating whether a wraparound of a value of the field is to be accounted for by the PHY device, and
transfer i) the timing packet and ii) the plurality of indicators to the PHY device for further processing of the timing packet based on the plurality of indicators and subsequent transmission of the timing packet from the network device;
the PHY device being configured to:
receive i) the timing packet from the MAC processor and ii) the plurality of indicators from the MAC processor,
embed, based on the plurality of indicators, timing information into the timing packet, and
forward the timing packet to one or more network ports of the network device for transmission of the timing packet from the network device.
17. The network device of claim 16 , wherein:
the timing packet is one of i) a timing packet generated by a host processor of the network device, the timing packet including a correction field into which the PHY device is to embed the timing information or ii) a timing packet previously received by the network device, the timing packet previously received by the network device including a correction field to be used for indicating a residence time of the timing packet in the network device,
the field in the timing packet at which the timing information is to be embedded into the timing packet by the PHY device is the correction field, and
the timing information to be embedded in the timing packet indicates one of i) a time corresponding to transmission of the timing packet from the network device or ii) a residence time of the timing packet in the network device.
18. The network device of claim 16 , wherein:
the MAC processor is configured to receive a timing packet that includes i) a timestamp and ii) a value of a correction field generated based on a clock maintained by a host processor of the network device, and
the PHY device is configured to embed the timing information into the timing packet at least by updating the value of the correction field based on a clock maintained by the PHY device of the network device.
19. The network device of claim 16 , wherein the PHY device is configured to:
locate, based on the location indicator and without parsing the timing packet to locate the field within the timing packet, the field in the timing packet at which the timing information is to be embedded into the timing packet by the PHY device,
determine a value of the field in the timing packet for embedding timing information into the timing packet by the PHY device,
determine, based on the wraparound indicator, whether the wraparound of the value of the field is to be accounted for by the PHY device,
in response to determining that the wraparound of the value of the field is to be accounted for, add additional time to the value of the field to account for the wraparound, and
update the value of the field in the timing packet to embed the timing information into the timing packet.
20. The network device of claim 19 , wherein:
the MAC processor is configured to generate the plurality of indicators to further include a checksum update indicator indicating whether a checksum update is needed for the timing packet, and
the PHY device is configured to,
determine, based on the checksum update indicator, whether a checksum update is needed for the timing packet, and
in response to determining that a checksum update is needed for the timing packet, perform an incremental update of a checksum trailer field in the timing packet.