[system-administrators-guide] Updates to Configuring PTP using ptp4l | based on SME feedback thank you mlichvar

[stephenw]

commit ec56e678203dbc77cbf7f3662bdb1dda2b5d8b30
Author: Stephen Wadeley <swadeley at redhat.com>
Date:   Mon Oct 14 21:24:31 2013 +0200

    Updates to Configuring PTP using ptp4l | based on SME feedback
    thank you mlichvar

 en-US/Configuring_PTP_using_ptp4l.xml |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)
---
diff --git a/en-US/Configuring_PTP_using_ptp4l.xml b/en-US/Configuring_PTP_using_ptp4l.xml
index 22b64dc..74dddcc 100644
--- a/en-US/Configuring_PTP_using_ptp4l.xml
+++ b/en-US/Configuring_PTP_using_ptp4l.xml
@@ -129,6 +129,9 @@ should include:
     <screen>~]# <command>yum install linuxptp</command></screen>
     This will install <application>ptp4l</application> and <application>phc2sys</application>.
   </para>
+    <para>
+      Do not run another service to set the system clocktime at the same time. If you intened to serve <systemitem class="protocol">PTP</systemitem> time using <systemitem class="protocol">NTP</systemitem>, see <xref linkend="Serving_PTP_time_with_NTP" />.
+    </para>
 </section>
 
 <section id="Starting_ptp4l">
@@ -314,7 +317,11 @@ The <application>phc2sys</application> program can be also started as a service
 <screen>~]# <command>systemctl start phc2sys</command></screen>
 When running as a service, options are specified in the <filename>/etc/sysconfig/phc2sys</filename> file. More information on the different <application>phc2sys</application> options can be found in the <filename>phc2sys(8)</filename> man page.
   </para>
-  </section>
+  <para>
+    Note that the examples in this section assume the command is run on a slave system or slave port.
+  </para>
+</section>
+
 <section id="Verifying_time_synchronization">
   <title>Verifying time synchronization</title>
   <para>
@@ -347,6 +354,11 @@ master  offset     632 s2 adj -28113 path delay 12443
 server   127.127.1.0
 fudge    127.127.1.0 stratum 0</screen>
   </para>
+    <note>
+    <para>
+      When the <systemitem class="protocol">DHCP</systemitem> client program, <application>dhclient</application>, receives a list of <systemitem class="protocol">NTP</systemitem> servers from the <systemitem class="protocol">DHCP</systemitem> server, it adds them to <filename>ntp.conf</filename> and restarts the service. To disable that feature, add <command>PEERNTP=no</command> to <filename>/etc/sysconfig/network</filename>.
+    </para>
+  </note>
 </section>