Abstract
In large-scale systems, such as Internet-based distributed systems, classical clock-synchronization solutions become impractical or poorly performing, due to the number of nodes and/or the distance among them. We present a global time service for world-wide systems, based on an innovative clock synchronization scheme, named CESIUMSPRAY. The service exhibits high precision and accuracy; it is virtually indefinitely scalable; and it is fault-tolerant. It is deterministic for real-time machinery in the local area, which makes it particularly well-suited for, though not limited to, large-scale real-time systems. The main features of our clock synchronization scheme can be summarized as follows: hybrid external/internal synchronization protocol improves effectiveness of synchronization; heterogeneous failure semantics for clocks and processors improves previous lower bounds on processors; two-level hierarchy improves scalability. The root of the hierarchy is the GPS satellite constellation, which "sprays" its reference time over a set of nodes provided with GPS receivers, one per local network. The second level of the hierarchy performs internal synchronization, further "spraying" the external time inside the local network.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 243-294 |
| Number of pages | 52 |
| Journal | Real-Time Systems |
| Volume | 12 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jan 1 1997 |
| Externally published | Yes |
ASJC Scopus subject areas
- Control and Optimization
- Modeling and Simulation
- Computer Networks and Communications
- Control and Systems Engineering
- Computer Science Applications
- Electrical and Electronic Engineering