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diff --git a/contrib/ntp/html/rdebug.htm b/contrib/ntp/html/rdebug.htm new file mode 100644 index 0000000..472b09f --- /dev/null +++ b/contrib/ntp/html/rdebug.htm @@ -0,0 +1,67 @@ +<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML Strict//EN"> +<html><head><title> +Debugging Hints for Reference Clock Drivers +</title></head><body><h3> +Debugging Hints for Reference Clock Drivers +</h3><hr> + +<p>The <a href = "ntpq.htm"> <code>ntpq</code></a> and <a href = +"ntpdc.htm"> <code>ntpdc</code> </a>utility programs can be used to +debug reference clocks, either on the server itself or from another +machine elsewhere in the network. The server is compiled, installed and +started using the command-line switches described in the <a href = +"ntpd.htm"> <code>ntpd</code> </a> page. The first thing to look for +are error messages on the system log. If none occur, the daemon has +started, opened the devices specified and waiting for peers and radios +to come up. + +<p>The next step is to be sure the RS232 messages, if used, are getting +to and from the clock. The most reliable way to do this is with an RS232 +tester and to look for data flashes as the driver polls the clock and/or +as data arrive from the clock. Our experience is that the overwhelming +fraction of problems occurring during installation are due to problems +such as miswired connectors or improperly configured device links at +this stage. + +<p>If RS232 messages are getting to and from the clock, the variables of +interest can be inspected using the <code>ntpq</code> program and +various commands described on the documentation page. First, use the +<code>pe</code> and <code>as</code> commands to display billboards +showing the peer configuration and association IDs for all peers, +including the radio clock peers. The assigned clock address should +appear in the <code>pe</code> billboard and the association ID for it at +the same relative line position in the <code>as</code> billboard. If +things are operating correctly, after a minute or two samples should +show up in the <code>pe</code> display line for the clock. + +<p>Additional information is available with the <code>rv</code> and +<code>clockvar</code> commands, which take as argument the association +ID shown in the <code>as</code> billboard. The <code>rv</code> command +with no argument shows the system variables, while the <code>rv</code> +command with association ID argument shows the peer variables for the +clock, as well as any other peers of interest. The <code>clockvar</code> +command with argument shows the peer variables specific to reference +clock peers, including the clock status, device name, last received +timecode (if relevant), and various event counters. In addition, a +subset of the <code>fudge</code> parameters is included. + +<p>The <code>ntpdc</code> utility program can be used for detailed +inspection of the clock driver status. The most useful are the +<code>clockstat</code> and <code>clkbug</code> commands described in the +document page. While these commands permit getting quite personal with +the particular driver involved, their use is seldom necessary, unless an +implementation bug shows up. + +<p>Most drivers write a message to the <code>clockstats</code> file as +each timecode or surrogate is received from the radio clock. By +convention, this is the last ASCII timecode (or ASCII gloss of a binary- +coded one) received from the radio clock. This file is managed by the +<code>filegen</code> facility described in the <code>ntpd</code> page +and requires specific commands in the configuration file. This forms a +highly useful record to discover anomalies during regular operation of +the clock. The scripts included in the <code>./scripts/stats</code> +directory can be run from a <code>cron</code> job to collect and +summarize these data on a daily or weekly basis. The summary files have +proven invaluable to detect infrequent misbehavior due to clock +implementation bugs in some radios. +<hr><address>David L. Mills (mills@udel.edu)</address></body></html> |