D012 DARPA Progress Report 1997

Scalable, High Speed Time Synchronization


  1. Develop autonomous peer discovery, configuration and deployment algorithms for a distributed time synchronization network in an arbitrary internet of thousands or millions of servers and clients.
  2. Significantly improve accuracy and reliability using distributed algorithms which take into account all locally available timekeeping information distributed by multicast and unicast means.
  3. Validate autonomous configuration technology as applicable to other distributed protocols, such as directory and routing services.


The approach is based on technology developed over the last decade for synchronizing computer network clocks in the Internet. The Network Time Protocol (NTP) is now deployed in an estimated total of over 100,000 hosts in the Internet. As this number grows, it is necessary to investigate protocols and algorithms which provide a autonomous, repairable configuration capability, in which an isolated client or server subnet can discover other servers and organize the topological connectivity to maximize the quality of synchronization, while obeying limits on network traffic and operating system overhead. The existing NTP Version 3 reference implementation will be used as the development vehicle in this investigation.

Recent Accomplishments

  1. Completed proof-of-concept implementation of autoconfigure scheme for automatically configuring a network of time servers.

  2. Completed proof-of-concept implementation of autokey scheme which automatically authenticates associations using public key cryptography and crafted hash algorithms.

  3. Completed implementation and documentation of a new NTP clock discipline algorithm that improves synchronization accuracy and lowers network overhead.

Current Plan

  1. Refine the autoconfigure scheme to fix certain shortcomings of the Unix socket model.
  2. Refine the autokey scheme to incorporate DNS certificates and complete the RSA PKI model.
  3. Complete deployment in CAIRN for a proof-of-concept demonstration.

Technology Transition

  1. Research findings, including results from analysis and experiment, as well as hardware and software descriptions, will be published in the open scientific literature and on the World Wide Web.
  2. Current status and briefing presentations will be made available on the World Wide Web.
  3. Sources and documentation for designated operating system software deliverables, including the Network Time Protocol Version 4, will be freely available from Internet FTP servers.
  4. Hardware documentation in the form of circuit schematics, PCB artwork and drill templates will be freely available from Internet FTP servers.
  5. Protocol specifications and associated documentation will be published in RFC form for consideration by the IETF standards apparatus.
  6. Research findings will be presented to the DoD and HPCC community in regular meetings sponsored wholly or in part by DARPA.
  7. Assistance will be provided to government agencies of the U.S. and other countries in setting up and operating networks of NTP servers.