1181834Sroberto<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2181834Sroberto 3181834Sroberto<html> 4181834Sroberto 5181834Sroberto <head> 6181834Sroberto <meta http-equiv="content-type" content="text/html;charset=iso-8859-1"> 7181834Sroberto <meta name="generator" content="HTML Tidy, see www.w3.org"> 8181834Sroberto <title>ntpdsim - Network Time Protocol (NTP) simulator</title> 9181834Sroberto <link href="scripts/style.css" type="text/css" rel="stylesheet"> 10181834Sroberto </head> 11181834Sroberto 12181834Sroberto <body> 13181834Sroberto <h3><tt>ntpdsim</tt> - Network Time Protocol (NTP) simulator</h3> 14181834Sroberto <img src="pic/alice47.gif" alt="gif" align="left"><a href="http://www.eecis.udel.edu/%7emills/pictures.html">from <i>Alice's Adventures in Wonderland</i>, Lewis Carroll</a> 15181834Sroberto <p>The mushroom knows all the command line options.</p> 16181834Sroberto <p>Last update: <csobj format="ShortTime" h="25" locale="00000409" region="0" t="DateTime" w="61">21:32</csobj> UTC <csobj format="LongDate" h="25" locale="00000409" region="0" t="DateTime" w="223">Friday, June 16, 2006</csobj></p> 17181834Sroberto <br clear="left"> 18181834Sroberto <h4>Related Links</h4> 19181834Sroberto <script type="text/javascript" language="javascript" src="scripts/links7.txt"></script> 20181834Sroberto <h4>Table of Contents</h4> 21181834Sroberto <ul> 22181834Sroberto <li><a href="#description">Description</a><br> 23181834Sroberto <li><a href="#configuration">Configuration</a> 24181834Sroberto <li><a href="#sample">Sample Configuration File</a> 25181834Sroberto </ul> 26181834Sroberto <h4 id="description">Description</h4> 27181834Sroberto <p>The ntpdsim program is used to simulate and study the behavior of an NTP daemon that derives its time from a number of different simulated time sources (servers). Each simulated server can be configured to have a different time offset, frequency offset, propagation delay, processing delay, network jitter and oscillator wander.</p> 28181834Sroberto <p>The ntpdsim program runs all the same selection, mitigation, and discipline algorithms as the actual ntpd daemon at the client. (It actually uses the same code). However, the input/output routines and servers are simulated. That is, instead of sending the client messages over the network to the actual servers, the client messages are intercepted by the ntpdsim program, which then generates the replies to those messages. The reply messages are carefully "inserted" into the input queue of the client at the right time according to the specified server properties (like propagation delay).</p> 29181834Sroberto <p>Each simulated server runs according to a specified script that describes the server properties at a particular time. Each script consists of a series of consecutive acts. Each act runs for a particular duration and specifies the frequency offset, propagation delay, processing delay, network jitter and oscillator wander of the server for that duration. Once the duration of an act expires, the simulated server reconfigures itself according to the properties specified in the next act.</p> 30181834Sroberto <h4 id="configuration">Configuration</h4> 31181834Sroberto <p>The ntpdsim program is configured by providing a configuration file at startup. The crux of the simulator configuration is specified using a <tt>simulate</tt> command, the syntax of which is given below. Note that all time quantities are in seconds and all frequency quantities are in parts per million (PPM):</p> 32181834Sroberto <p><<i>simulate_command</i>> ::= <tt>simulate</tt> { <<i>init_statement_list</i>> <<i>server_list</i>> }<br> 33181834Sroberto <<i>init_statement_list</i>> ::= <init_statement_list> <init_statement> | <init_statement><br> 34181834Sroberto <<i>init_statement</i>> ::= <tt>beep_delay</tt> = <number> | <tt>simulation_duration</tt> = <number><br> 35181834Sroberto <<i>server_list</i>> ::= <<i>server_list</i>> <server> | <server><br> 36181834Sroberto <<i>server_list</i>> ::= <tt>server</tt> = <address> { <tt>server_offset</tt> = <number> <act_list> }<br> 37181834Sroberto <<i>act_list</i>> ::= <<i>act_list</i>> <<i>act</i>> | <<i>act</i>><br> 38181834Sroberto <<i>act</i>> ::= <tt>duration</tt> = <number> { <<i>act_stmt_list</i>> }<br> 39181834Sroberto <<i>act_stmt_list</i>> ::= <<i>act_stmt_list</i>> <<i>act_stmt</i>> | <<i>act_stmt</i>><br> 40181834Sroberto <<i>act_stmt</i>> ::= <tt>freq_offset</tt> = <number> | <tt>wander</tt> = <number> | <tt>jitter</tt> = <number> | <tt>prop_delay</tt> = <number> | <tt>proc_delay</tt> = <number></p> 41181834Sroberto <p>In addition to the simulate command, other standard NTP configuration commands can be specified. These commands have the same meaning as in the ntpd configuration. Note that newlines are <b>not</b> significant within the simulate command even though they are used to mark the end of a normal NTP configuration command.</p> 42181834Sroberto <h4 id="sample">Sample Configuration File</h4> 43181834Sroberto <p>A sample ntpdsim configuration file is given below. It specifies two simulated servers, each of which has two acts.</p> 44181834Sroberto <pre> 45181834Sroberto # Client configuration 46181834Sroberto disable kernel 47181834Sroberto server pogo 48181834Sroberto driftfile ./ntp.drift 49181834Sroberto statsdir ./ntpstats/ 50181834Sroberto filegen loopstats type day enable 51181834Sroberto filegen peerstats type day enable 52181834Sroberto 53181834Sroberto # Simulation configuration 54181834Sroberto simulate { 55181834Sroberto simulation_duration = 86400 56181834Sroberto beep_delay = 3600 57181834Sroberto 58181834Sroberto # Server 1 59181834Sroberto server = louie.udel.edu { 60181834Sroberto server_offset = 0 61181834Sroberto duration = 50000 { 62181834Sroberto freq_offset = 400 63181834Sroberto wander = 1.0 64181834Sroberto jitter = 0.001 65181834Sroberto prop_delay = 0.001 66181834Sroberto proc_delay = 0.001 67181834Sroberto } 68181834Sroberto duration = 6400 { 69181834Sroberto freq_offset = 200 70181834Sroberto wander = 1.0 71181834Sroberto jitter = 0.001 72181834Sroberto prop_delay = 0.001 73181834Sroberto proc_delay = 0.001 74181834Sroberto } 75181834Sroberto } 76181834Sroberto 77181834Sroberto # Server 2 78181834Sroberto server = baldwin.udel.edu { 79181834Sroberto server_offset = 0.02 80181834Sroberto duration = 10000 { 81181834Sroberto freq_offset = 400 82181834Sroberto wander = 1.0 83181834Sroberto jitter = 0.001 84181834Sroberto prop_delay = 0.5 85181834Sroberto proc_delay = 0.001 86181834Sroberto } 87181834Sroberto duration = 60000 { 88181834Sroberto freq_offset = 200 89181834Sroberto wander = 1.0 90181834Sroberto jitter = 0.05 91181834Sroberto prop_delay = 0.005 92181834Sroberto proc_delay = 0.001 93181834Sroberto } 94181834Sroberto } 95181834Sroberto } 96181834Sroberto </pre> 97181834Sroberto <hr> 98181834Sroberto <address><a href="mailto:skamboj@udel.edu">Sachin Kamboj</a></address> 99181834Sroberto <script type="text/javascript" language="javascript" src="scripts/footer.txt"></script> 100181834Sroberto </body> 101181834Sroberto 102181834Sroberto</html> 103
