Time Synchronization
====================

This section explores the core protocols used to synchronize clocks across networked systems. Accurate timekeeping is essential for logging, event correlation, encryption, and distributed computing.

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   NTP
   PTP
   SNTP

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   * - Protocol
     - Description
     - Use Case
   * - NTP (Network Time Protocol)
     - Synchronizes system clocks to within milliseconds.  
       *Uses hierarchical stratum levels and tolerates network jitter.*
     - Server sync, log timestamps, certificate validation
   * - PTP (Precision Time Protocol)
     - Offers sub-microsecond synchronization using hardware timestamping.  
       *Ideal for real-time and deterministic systems.*
     - Telecom, stock exchanges, automation networks
   * - SNTP (Simple Network Time Protocol)
     - A simplified, lightweight version of NTP.  
       *Lower precision but easy to implement.*
     - IoT devices, consumer electronics

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   .. tab-item:: NTP (Network Time Protocol)

      **RFC:** RFC 5905

      **Main Features:**

      - Synchronizes clocks across devices to millisecond accuracy
      - Hierarchical model (stratum levels 1–15)
      - Compensates for latency and jitter
      - Secure with NTS (NTP over TLS)

      **Use Cases:**

      - Server synchronization in data centers
      - Accurate timestamps for logs and security
      - Time-based certificate verification

      **Alternative Protocols:**

      - SNTP – Simpler, for embedded systems
      - PTP – For sub-microsecond precision in real-time networks

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         **Let us learn more about NTP:**

         * :ref:`Learnings in this section <NTP_step1>`

         * :ref:`Terminology <NTP_step2>`

         * :ref:`Version Info <NTP_step3>`

         * :ref:`NTP Version&RFC Details <NTP_step5>`

         * :ref:`NTP Basic Setup on Ubuntu using IPv4 <NTP_step20>`

         * :ref:`NTP Basic Setup on Ubuntu using IPv6 <NTP_step21>`

         * :ref:`NTP Protocol Packet Details <NTP_step6>`

         * :ref:`NTP Usecases <NTP_step7>`

         * :ref:`NTP Basic Features <NTP_step8>`

         * :ref:`NTP Feature : Time Synchronization <NTP_step9>` 

         * :ref:`NTP Feature : Hierarchical Architecture <NTP_step10>`

         * :ref:`NTP Feature : High Accuracy <NTP_step11>`  

         * :ref:`NTP Feature : Fault Tolerance <NTP_step12>`  

         * :ref:`NTP Feature : Clock Filtering and Selection <NTP_step13>`

         * :ref:`NTP Feature : Security Support (NTPv4) <NTP_step14>`

         * :ref:`NTP Feature : Support <NTP_step15>`   

         * :ref:`NTP Feature : Dynamic Server Discovery <NTP_step16>` 

         * :ref:`NTP Feature : Cross-Platform Compatibility <NTP_step17>`

         * :ref:`NTP Feature : Low Bandwidth Usage <NTP_step18>`

         * :ref:`Reference links <NTP_step19>`

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   .. tab-item:: PTP (Precision Time Protocol)

      **RFC:** IEEE 1588

      **Main Features:**

      - Achieves microsecond to sub-microsecond synchronization
      - Uses hardware timestamping for precision
      - Operates in master-slave hierarchy
      - Designed for LANs and deterministic environments

      **Use Cases:**

      - Time-critical networks (e.g., industrial automation)
      - Telecom synchronization
      - Financial market timing

      **Alternative Protocols:**

      - NTP – Suitable for broader, less precise applications
      - GPS – External time source for grandmasters

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         **Let us learn more about PTP:**

         * :ref:`Learnings in this section <PTP_step1>`

         * :ref:`Terminology <PTP_step2>`

         * :ref:`Version Info <PTP_step3>`

         * :ref:`PTP Version&RFC Details <PTP_step5>`

         * :ref:`PTP Basic Setup on Ubuntu using IPv4 <PTP_step19>`

         * :ref:`PTP Basic Setup on Ubuntu using IPv6 <PTP_step20>`

         * :ref:`PTP Protocol Packet Details <PTP_step6>`

         * :ref:`PTP Usecases <PTP_step7>`

         * :ref:`PTP Basic Features <PTP_step8>`

         * :ref:`PTP Feature : High Precision Time Sync <PTP_step9>` 

         * :ref:`PTP Feature : Master-Slave Architecture <PTP_step10>`

         * :ref:`PTP Feature : Hardware Timestamping <PTP_step11>`  

         * :ref:`PTP Feature : Event and General Messages <PTP_step12>`  

         * :ref:`PTP Feature : Loopback Testing Support <PTP_step13>`

         * :ref:`PTP Feature : Delay Measurement and Mechanism <PTP_step14>`

         * :ref:`PTP Feature : Best Master Clock Algorithm <PTP_step15>`   

         * :ref:`PTP Feature : Multicast and Unicast Support <PTP_step16>` 

         * :ref:`PTP Feature : Profile-Based Configuration <PTP_step17>` 

         * :ref:`PTP Feature : Scalability <PTP_step18>`

         * :ref:`Reference links <PTP_step21>`


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   .. tab-item:: SNTP (Simple Network Time Protocol)

      **RFC:** RFC 4330, RFC 5905

      **Main Features:**

      - Lightweight implementation of NTP
      - Suitable for simple or embedded systems
      - Limited error handling and jitter correction
      - Easy to integrate into devices

      **Use Cases:**

      - Time sync on IoT sensors and smart appliances
      - Consumer electronics (TVs, clocks)
      - Low-power or limited-resource systems

      **Alternative Protocols:**

      - NTP – For full-featured, secure synchronization
      - PTP – For microsecond-level accuracy in deterministic networks

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         **Let us learn more about SNTP:**

         * :ref:`Learnings in this section <SNTP_step1>`

         * :ref:`Terminology <SNTP_step2>`

         * :ref:`Version Info <SNTP_step3>`

         * :ref:`SNTP Version&RFC Details <SNTP_step5>`

         * :ref:`SNTP Basic Setup on Ubuntu using IPv4 <SNTP_step18>`

         * :ref:`SNTP Basic Setup on Ubuntu using IPv6 <SNTP_step19>`

         * :ref:`SNTP Protocol Packet Details <SNTP_step6>`

         * :ref:`SNTP Usecases <SNTP_step7>`

         * :ref:`SNTP Basic Features <SNTP_step8>`

         * :ref:`SNTP Feature : Simplicity <SNTP_step9>` 

         * :ref:`SNTP Feature : Time Synchronization <SNTP_step10>`

         * :ref:`SNTP Feature : UDP-Based Communication <SNTP_step11>`  

         * :ref:`SNTP Feature : Low Overhead <SNTP_step12>`  

         * :ref:`SNTP Feature : Compatibility with NTP servers <SNTP_step13>`

         * :ref:`SNTP Feature : Support for IPv4 and IPv6 <SNTP_step14>`

         * :ref:`SNTP Feature : One-Way Communication <SNTP_step15>`   

         * :ref:`SNTP Feature : Periodic Updates <SNTP_step16>` 

         * :ref:`Reference links <SNTP_step17>`

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