Tripleo PTP (Precision Time Protocol) support

This spec introduces support for a time synchronization
method called PTP (defined in the IEEE 1588-2008) which
provides better time accuracy than NTP in general. With
hardware timestamping support on the host, PTP can
achieve clock accuracy in the sub-microsecond range,
making it suitable for measurement and control systems.

Change-Id: I3e5cc2e854eb8e0374e36640816dcdb5fc8a773f

specs/queens/tripleo-ptp.rst

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+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+
+=============================================
+TripleO PTP (Precision Time Protocol) Support
+=============================================
+
+https://blueprints.launchpad.net/tripleo/+spec/tripleo-ptp
+
+This spec introduces support for a time synchronization method called PTP [0]
+which provides better time accuracy than NTP in general. With hardware
+timestamping support on the host, PTP can achieve clock accuracy in the
+sub-microsecond range, making it suitable for measurement and control systems.
+
+Problem Description
+===================
+
+Currently tripleo deploys NTP services by default which provide millisecond
+level time accuracy, but this is not enough for some cases:
+
+* Fault/Error events will include timestamps placed on the associated event
+  messages, retrieved by detectors with the purpose of accurately identifying
+  the time that the event occurred. Given that the target Fault Management
+  cycle timelines are in tens of milliseconds on most critical faults, events
+  ordering may reverse against actual time if precison and accuracy of clock
+  synchronization are in the same level of accuracy.
+
+* NFV C-RAN (Cloud Radio Access Network) is looking for better time
+  sychronization and distribution in micro-second level accuracy as alternative
+  for NTP, PTP has been evaluated as one of the technologies.
+
+This spec is not intended to cover all the possible ways of PTP usage, rather
+to provide a basic deployment path for PTP in tripleo with default
+configuration set to support PTP Ordinary Clock (slave mode); the master mode
+ptp clock configuration is not in the scope of this spec, but shall be deployed
+by user to provide the time source for the PTP Ordinary Clock. The full support
+of PTP capability can be enhanced further based on this spec.
+
+User shall be aware of the fact that NTP and PTP can not be configured together
+on the same node without a coordinator program like timemaster which is also
+provided by linuxptp package. How to configure and use timemaster is not in the
+scope of this spec.
+
+Proposed Change
+===============
+
+Overview
+--------
+
+Provide the capability to configure PTP as time synchronization method:
+
+* Add PTP configuration file path in overcloud resource registry.
+
+* Add puppet-tripleo profile for PTP services.
+
+* Add tripleo-heat-templates composable service for PTP.
+
+Retain the current default behavior to deploy NTP as time synchronization
+source:
+
+* The NTP services remain unchanged as the default time synchronization method.
+
+* The NTP services must be disabled on nodes where PTP are deployed.
+
+Alternatives
+------------
+
+The alternative is to continue to use NTP.
+
+Security Impact
+---------------
+
+Security issues originated from PTP will need to be considered.
+
+Other End User Impact
+---------------------
+
+Users will get more accurate time from PTP.
+
+Performance Impact
+------------------
+
+No impact with default deployment mode which uses NTP as time source.
+
+Other Deployer Impact
+---------------------
+
+The operator who wants to use PTP should identify and provide the PTP capable
+network interface name and make sure NTP is not deployed on the nodes where PTP
+will be deployed. The default PTP network interface name is set to 'nic1' where
+user should change it according to real interface name. By default, PTP will
+not be deployed unless explicitly configured.
+
+Developer Impact
+----------------
+
+None
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  zshi
+
+Work Items
+----------
+
+* Puppet-tripleo profile for PTP services
+* Tripleo-heat-templates composable service for PTP deployment
+
+Dependencies
+============
+
+* Puppet module for PTP services: ptp [1]
+* The linuxptp RPM must be installed, and PTP capable NIC must be identified.
+* Refer to linuxptp project page [2] for the list of drivers that support the
+  PHC (Physical Hardware Clock) subsystem.
+
+Testing
+=======
+
+The deployment of PTP should be testable in CI.
+
+Documentation Impact
+====================
+
+The deployment documation will need to be updated to cover the configuration of
+PTP.
+
+References
+==========
+
+* [0] https://standards.ieee.org/findstds/standard/1588-2008.html
+* [1] https://github.com/redhat-nfvpe/ptp
+* [2] http://linuxptp.sourceforge.net