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EP-4513294-B1 - PASSIVE CLOCK SYNCHRONIZATION FOR TIMING

EP4513294B1EP 4513294 B1EP4513294 B1EP 4513294B1EP-4513294-B1

Inventors

  • COOLIDGE, IAN KENNETH
  • VALOTH, SHAHIN

Dates

Publication Date
20260513
Application Date
20240821

Claims (15)

  1. A method (400) for synchronization in a multi-interface card environment, comprising: transmitting (402), by a computing device (300), a synchronization message (208) to a first interface card (104) through a passive splitter (108), wherein the passive splitter (108) is further coupled to at least one second interface card (106); receiving (404), by the computing device (300), a delay request (212) transmitted by the first interface card (104) through the passive splitter (108); transmitting (406), by the computing device (300), a delay response (216) to the first interface card (104) through the passive splitter (108); listening (408), by the second interface card (106), to the delay request (212) and the delay response (216) through the passive splitter (108); computing, by the computing device (300) or the first interface card (104), a delay based on: timestamps recorded when the synchronization message (208) was transmitted by the computing device (300) and received by the first interface card (104) and the delay request (212) was transmitted by the first interface card (104) and the delay request (212) was received by the computing device (300), or based on timestamps recorded when the delay request (212) was transmitted by the first interface card (104) and received by the computing device (300) and when the delay response (216) was transmitted by the computing device (300) and received by the first interface card (104); characterized in that the method further comprises: receiving, by the second interface card (106), the delay from the first interface card (104) or the computing device (300) through the passive splitter (108); and synchronizing (410), by the second interface card (106), to at least one of the computing device (300) or the first interface card (104) based on the delay.
  2. The method (400) of claim 1, wherein the second interface card synchronizes to the computing device (300); and/or wherein the second interface card synchronizes to the first interface card (104).
  3. The method (400) of any one of the preceding claims, wherein the passive splitter (108) is a passive optical splitter (108).
  4. The method (400) of claim 3, wherein the passive splitter (108) is a 1:2 passive optical splitter (108).
  5. The method (400) of any one of the preceding claims, where the computing device (300) comprises a leader clock (102, 202) in a server.
  6. The method (400) of any one of the preceding claims, wherein the first and second interface cards (106) are network interface cards, NICs.
  7. The method (400) of any one of the preceding claims, wherein the first and second interface cards (106) are peripheral component interconnect express, PCIe, cards.
  8. The method (400) of any one of the preceding claims, further comprising: listening, by a third interface card coupled to the passive splitter (108), to the delay request (212) and the delay response (216) through the passive splitter (108); and synchronizing, by the third interface card, to at least one of the computing device (300) or the first interface card (104) based on the listening.
  9. A system for synchronization in a multi-interface card environment, the system comprising: a computing device (300); a passive splitter (108); and a plurality of interface cards including a first interface card (104) and a second interface card (106), the plurality of interface cards coupled to the computing device (300) through the passive splitter (108); wherein the computing device (300) is configured to: transmit (402) a synchronization message (208) to the first interface card (104) through the passive splitter (108); receive (404) a delay request (212) transmitted by the first interface card (104) through the passive splitter (108); transmit (406) a delay response (216) to the first interface card (104) through the passive splitter (108); wherein the computing device (300) or the first interface card (104) is configured to compute a delay based on: timestamps recorded when the synchronization message (208) was transmitted by the computing device (300) and received by the first interface card (104) and the delay request (212) was transmitted by the first interface card (104) and the delay request (212) was received by the computing device (300), or based on timestamps recorded when the delay request (212) was transmitted by the first interface card (104) and received by the computing device (300) and when the delay response (216) was transmitted by the computing device (300) and received by the first interface card (104);wherein the second interface card (106) is configured to: listen (408) to the delay request (212) and the delay response (216) through the passive splitter (108); characterized in that the second interface card (106) is further configured to: receive the delay from the first interface card (104) or the computing device (300) through the passive splitter (108); and synchronize (410) to at least one of computing device (300) or the first interface card (104) based on the delay.
  10. The system of claim 9, wherein the second interface card synchronizes to the computing device (300); and/or wherein the second interface card synchronizes to the first interface card (104).
  11. The system of any one of claims 9 or 10, wherein the passive splitter (108) is a passive optical splitter (108).
  12. The system of claim 11, wherein the passive splitter (108) is a 1:2 passive optical splitter (108).
  13. The system of any one of claims 9 to 12, where the computing device (300) comprises a leader clock (102, 202) in a server; and/or wherein the first and second interface cards (106) are network interface cards.
  14. The system of any one of claims 9 to 13, wherein the first and second interface cards (106) are peripheral component interconnect express, PCIe, cards.
  15. The system of any one of claims 9 to 14, further comprising a third interface card coupled to the passive splitter (108), the third interface card configured to: listen to the delay request (212) and the delay response (216) through the passive splitter (108); and synchronize to at least one of the computing device (300) or the first interface card (104) based on the listening.

Description

BACKGROUND Precision time protocol (PTP) is a network-based time synchronization method. PTP is often used to provide clock information from a leader clock to an interface card. The interface card is typically connected to the leader clock via a single link, such as a fiber or cable. When multiple interface cards are connected to a leader clock, multiple fibers or cables are needed to make individual connections for the precision time protocol to operate properly which can be costly. Additionally, without dedicated circuitry, interface card interconnects may cause an inaccurate transfer of clock information due to the jittery nature of the connections between the multiple interface cards and the leader clock. US 2022/173884 A1 discloses techniques for determining an offset between clocks in a network. BRIEF SUMMARY The present disclosure provides for an architecture for a multi-interface card environment, such as a server that includes multiple network interface cards (NICs) or peripheral component interconnect express (PCIe) cards. The architecture includes a passive optical splitter coupled between a leader clock and the multiple interface cards, such as NICs, PCIe cards, etc. The optical splitter can be used to distribute clock time from the leader clock to the NICs. The architecture provides for distribution of timing in a scalable manner in the multi-NIC environments for cloud deployments. The claimed subject-matter is defined in the independent claims. One aspect of the disclosure provides a method for synchronization in a multi-interface card environment. The method includes transmitting, by a computing device, a synchronization message to a first interface card through a passive splitter, wherein the passive splitter is further coupled to at least one second interface card; receiving, by the computing device, a delay request transmitted by the first interface card through the passive splitter; transmitting, by the computing device, a delay response to the first interface card through the passive splitter; listening, by the second interface card, to the delay request and the delay response through the passive splitter; and synchronizing, by the second interface card, to at least one of the computing device or the first interface card based on the listening. According to some examples, the second interface card synchronizes to the computing device. According to some examples, the second interface card synchronizes to the first interface card. According to some examples, the passive splitter is a passive optical splitter, such as a 1:2 passive optical splitter. In some examples, the computing device may be a leader clock in a server. The first and second interface cards may be network interface cards (NICs). In other examples, the first and second interface cards may be peripheral component interconnect express (PCIe) cards. In some examples, the method may further include listening, by a third interface card coupled to the passive splitter, to the delay request and the delay response through the passive splitter; and synchronizing, by the third interface card, to at least one of the computing device or the first interface card based on the listening. Another aspect of the disclosure provides a system for synchronization in a multi-interface card environment, the system comprising a computing device, a splitter, and a plurality of interface cards coupled to the computing device through the splitter. The computing device may be configured to transmit a synchronization message to a first interface card through the splitter, receive a delay request transmitted by the first interface card through the splitter, transmit a delay response to the first interface card through the splitter. The second interface card may be configured to listen to the delay request and the delay response through the passive splitter, and synchronize to at least one of computing device or the first interface card based on the listening. According to some examples, the second interface card synchronizes to the computing device. In other examples, the second interface card synchronizes to the first interface card. The passive splitter may be, for example, a passive optical splitter, such as a 1:2 passive optical splitter. The computing device may be, for example, a leader clock in a server. The first and second interface cards may be network interface cards, peripheral component interconnect express (PCIe) cards, or other interface cards. In some example systems, a third interface card may be coupled to the passive splitter, the third interface card configured to listen to the delay request and the delay response through the passive splitter; and synchronize to at least one of the computing device or the first interface card based on the listening. BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1A-1D depict block diagrams of example passive clock synchronization architectures according to aspects of the disclosure.Fig. 2 depicts a block di