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13: <h3><tt>ntpdsim</tt> - Network Time Protocol (NTP) Simulator</h3>
14: <img src="pic/oz2.gif" alt="gif" align="left"><a href="http://www.eecis.udel.edu/%7emills/pictures.html">from <i>The Wizard of Oz</i>, L. Frank Baum</a>
15: <p>All in a row.</p>
16: <p>Last update: <csobj format="ShortTime" h="25" locale="00000409" region="0" t="DateTime" w="61">15:56</csobj> UTC <csobj format="LongDate" h="25" locale="00000409" region="0" t="DateTime" w="250">Sunday, March 02, 2008</csobj></p>
17: <br clear="left">
18: <h4>Related Links</h4>
19: <script type="text/javascript" language="javascript" src="scripts/manual.txt"></script>
20: <h4>Table of Contents</h4>
21: <ul>
22: <li><a href="#description">Description</a><br>
23: <li><a href="#configuration">Configuration</a>
24: <li><a href="#sample">Sample Configuration File</a>
25: </ul>
26: <h4 id="description">Description</h4>
27: <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>
28: <p>The ntpdsim program runs all the same selection, mitigation, and discipline
29: algorithms as the actual ntpd daemon at the client. (It actually
30: uses the same code). However, the input/output routines and servers are simulated.
31: That is, instead of sending the client messages over the network
32: to the actual servers, the client messages are intercepted by the ntpdsim
33: program, which then generates the replies to those messages. The reply messages
34: are carefully "inserted" into the input queue of the client at the right time
35: according to the specified server properties (like propagation delay).</p>
36: <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>
37: <h4 id="configuration">Configuration</h4>
38: <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>
39: <p><<i>simulate_command</i>> ::= <tt>simulate</tt> { <<i>init_statement_list</i>> <<i>server_list</i>> }<br>
40: <<i>init_statement_list</i>> ::= <init_statement_list> <init_statement> | <init_statement><br>
41: <<i>init_statement</i>> ::= <tt>beep_delay</tt> = <number> | <tt>simulation_duration</tt> = <number><br>
42: <<i>server_list</i>> ::= <<i>server_list</i>> <server> | <server><br>
43: <<i>server_list</i>> ::= <tt>server</tt> = <address> { <tt>server_offset</tt> = <number> <act_list> }<br>
44: <<i>act_list</i>> ::= <<i>act_list</i>> <<i>act</i>> | <<i>act</i>><br>
45: <<i>act</i>> ::= <tt>duration</tt> = <number> { <<i>act_stmt_list</i>> }<br>
46: <<i>act_stmt_list</i>> ::= <<i>act_stmt_list</i>> <<i>act_stmt</i>> | <<i>act_stmt</i>><br>
47: <<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>
48: <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>
49: <h4 id="sample">Sample Configuration File</h4>
50: <p>A sample ntpdsim configuration file is given below. It specifies two simulated servers, each of which has two acts.</p>
51: <pre>
52: # Client configuration
53: disable kernel
54: server pogo
55: driftfile ./ntp.drift
56: statsdir ./ntpstats/
57: filegen loopstats type day enable
58: filegen peerstats type day enable
59:
60: # Simulation configuration
61: simulate {
62: simulation_duration = 86400
63: beep_delay = 3600
64:
65: # Server 1
66: server = louie.udel.edu {
67: server_offset = 0
68: duration = 50000 {
69: freq_offset = 400
70: wander = 1.0
71: jitter = 0.001
72: prop_delay = 0.001
73: proc_delay = 0.001
74: }
75: duration = 6400 {
76: freq_offset = 200
77: wander = 1.0
78: jitter = 0.001
79: prop_delay = 0.001
80: proc_delay = 0.001
81: }
82: }
83:
84: # Server 2
85: server = baldwin.udel.edu {
86: server_offset = 0.02
87: duration = 10000 {
88: freq_offset = 400
89: wander = 1.0
90: jitter = 0.001
91: prop_delay = 0.5
92: proc_delay = 0.001
93: }
94: duration = 60000 {
95: freq_offset = 200
96: wander = 1.0
97: jitter = 0.05
98: prop_delay = 0.005
99: proc_delay = 0.001
100: }
101: }
102: }
103: </pre>
104: <hr>
105: <address><a href="mailto:skamboj@udel.edu">Sachin Kamboj</a></address>
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