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Hardware Support for Clock Synchronization in Distributed Systems

This document presents an overview of hardware support mechanisms for clock synchronization in distributed systems. It focuses on achieving precision and accuracy in clock synchronization using techniques such as NTP over LANs and GPS-based synchronization methods. Key objectives include internal and external clock synchronization while maintaining low oscillator drift and good stability. It discusses requirements for hardware clocks, fine-grained rate adjustments, and timestamp mechanisms critical for network communications. A prototype implementation is briefly described, showcasing the essential functions of hardware-supported timestamping.

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Hardware Support for Clock Synchronization in Distributed Systems

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  1. Hardware Support for Clock Synchronization in Distributed Systems Martin Horauer University of Technology Vienna Department of Computer Technology

  2. LANs (hardware) precision, accuracy NTP LANs (software) 1ms LANs (hardware) 1s GPS PLL 1ns 10m 1 km distance 100m Objectives InternalClock Synchronization: | Cp(t) - Cq(t) |  External Clock Synchronization: | Cp(t) - t |  

  3. OCXO or XO + Rate Synchronization Hardware Support Clock ASIC UTCSU Requirements • Hardware Clock • small oscillator drift • good stability • fine grained • rate and state adjustable • Access to an external time reference • Timestamp Messages • tight coupling of timestamp mechanisms to the network medium

  4. Software Timestamping Cq(t) - Cp(t)  TR – TS - [ - ]  = max - min

  5. Timestamping with HardwareSupport

  6. Timestamping with HardwareSupport Cq(t) - Cp(t)  TR – TS - [ - ]  = max - min

  7. Hardware Support for Clock Synchronization

  8. Transmit TS FCS Transmit TS FCS Transmit Timestamping: Preamble User Data FCS SFD Dest. Addr. Src. Addr. TF = Receive CRC check: FCS User Data Dest. Addr. Src. Addr. TF Transmit TS FCS Receive TS Receive Timestamping: FCS Preamble User Data SFD Dest. Addr. Src. Addr. TF Transmit TS Receive TS FCS Clock Synchronization Packet Timestamping

  9. Hardware Support for Clock Synchronization

  10. Prototype Implementation

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