๐ฏ What is NTP?
Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks. NTP is intended to synchronize all participating computers to within a few milliseconds of Coordinated Universal Time (UTC).
- Stratum Levels: Hierarchy of time sources (0-15)
- Precision: Can achieve sub-millisecond accuracy on LANs
- Robustness: Handles network delays, jitter, and clock drift
๐งฎ NTP Algorithm Fundamentals
NTP uses a four-timestamp exchange to calculate clock offset and network delay:
- Tโ: Client originate timestamp (when request is sent)
- Tโ: Server receive timestamp (when server receives request)
- Tโ: Server transmit timestamp (when server sends response)
- Tโ: Client receive timestamp (when client receives response)
Clock Offset: ฮธ = ((Tโ - Tโ) + (Tโ - Tโ)) / 2
Round-trip Delay: ฮด = (Tโ - Tโ) - (Tโ - Tโ)
๐ Network Scenarios
- LAN: Low latency (1-10ms), minimal jitter, high precision
- MAN: Metropolitan networks (10-50ms), moderate jitter
- WAN: Wide area networks (50-200ms), variable delays
- Global: Intercontinental (200ms+), high asymmetry
- Noisy: Added random variations in delay
- Asymmetric: Different delays for request vs response
โ๏ธ Client Parameters
- Initial Offset: Starting time difference from server
- Drift Rate (ppm): Clock frequency error in parts per million
- Sync Interval: How often synchronization occurs
- Sync Period: Duration of each sync process
- Packet Interval: Time between individual NTP packets
Note: Real clocks drift due to temperature, aging, and manufacturing tolerances.
๐ฅ๏ธ Server Parameters
- Server Error: Random uncertainty in server's reference time
- Server Delay: Processing time before responding to requests
- Stratum 1: Directly connected to reference time sources (GPS, atomic clocks)
๐ Performance Metrics
- Current Offset: Instantaneous time difference
- Average Offset: Mean absolute synchronization error
- Offset Std Dev: Consistency of synchronization
- Sync Accuracy: Percentage accuracy (100% = perfect sync)
- Network Jitter: Variation in round-trip delays
- Round-trip Delay: Total network transit time
๐ฎ How to Use This Simulation
- Choose Network Scenario: Select from predefined network conditions or use custom settings
- Adjust Parameters: Modify client/server settings to see their effects
- Start Simulation: Click "Start Simulation" to begin continuous synchronization
- Observe Behavior: Watch the clocks, packet animations, and performance chart
- Manual Actions: Use "Synchronize Now" or "Send Packet" for step-by-step observation
- Analyze Results: Study the RTT vs Sync Error chart to understand performance
๐ฌ Experimental Observations
- Clock Drift Effect: Notice how clocks diverge without synchronization
- Network Impact: Higher RTT generally correlates with larger sync errors
- Jitter Handling: NTP's damping factor reduces oscillations
- Asymmetry Problems: Unequal network delays affect accuracy
- Convergence Time: Multiple packets needed for stable synchronization
๐งช Educational Experiments
- Basic Sync: Start with LAN scenario, observe quick convergence
- Drift Analysis: Set high drift rate, see gradual divergence
- Network Effects: Compare LAN vs WAN vs Global scenarios
- Asymmetry Impact: Use asymmetric scenarios, note accuracy loss
- Jitter Resistance: Test noisy networks, observe NTP's robustness
- Parameter Tuning: Adjust sync intervals and damping effects
๐ก Key Insights
- NTP Accuracy: Typically achieves 1-50ms accuracy over internet
- Stratum Hierarchy: Lower stratum numbers = higher accuracy
- Fault Tolerance: Can handle server failures and network issues
- Scalability: Hierarchical design supports millions of clients
- Security: Modern NTP includes authentication mechanisms
โจ๏ธ Keyboard Shortcuts
- F1 or Ctrl+H: Open/close this help guide
- Escape: Close this modal
- Space: Start/stop simulation
- S: Manual synchronization
- P: Send single packet
- C: Clear chart data