D012 DARPA Progress Report 1995

Scalable, High Speed Time Synchronization


The objectives of this work are: (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 proof of concept of 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 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

Not applicable; this is a new start.

Current Plan

Develop and refine algorithms for autonomous synchronization subnet discovery and configuration, as well as data refinement to improve accuracy and reliability.

Develop and refine enhancements for the NTP Version 3 architecture and protocol to support the new algorithms. Designated NTP Version 4, this includes a new distributed mode of operation which uses IP multicast to distribute timekeeping data to a designated subnet.

Technology Transition

Research findings, including results from analysis and experiment, as well as hardware and software descriptions, will be published in the open scientific literature. Sources and documentation for designated operating system software deliverables, including the proposed Network Time Protocol Version 4, will be freely available from Internet ftp servers. Hardware documentation in the form of circuit schematics, PCB artwork and drill templates for designated hardware deliverables, including a precision clock board peripheral, will be freely available from Internet ftp servers. Protocol specifications and associated documentation will be published in RFC form for consideration by the IETF standards apparatus. Research findings will be presented to the DoD and HPCC community in regular meetings sponsored wholly or in part by ARPA.