Sync mechanism between Neutron and Nuage VSD

This spec describes in brief the mechanism to sync state
between Neutron and Nuage VSD

Change-Id: I1ba823d15ef42c85165e5831e7d4b28dcd3fc6b9

specs/juno/nuage-neutron-sync.rst

@@ -0,0 +1,118 @@
+=====================================================================
+Add the functionality to sync resources between Neutron and Nuage VSD
+=====================================================================
+
+https://blueprints.launchpad.net/neutron/+spec/nuage-neutron-sync
+
+The purpose of this blueprint is to add functionality to sync resources
+between Neutron and Nuage VSD(Virtualized Services Directory).
+
+Problem description
+===================
+
+If there is any inconsistency in the state of neutron and the VSD
+database, there is no way to sync the resources between them.
+
+Proposed change
+===============
+
+The proposed change is to introduce support for state synchronization between
+neutron and VSD in the Nuage plugin
+
+In case Nuage VSD loses its database or the database is restored using a backup
+copy, there is a possibility that the resources in Neutron  and VSD are not in sync
+and this can lead to unexpected behavior. The sync will run as part of Nuage plugin
+at regular intervals.
+
+Neutron is considered as the master. The sync logic will get the state from Neutron and will
+send it to VSD. VSD will compare this state with its own state and if there are less resources
+in VSD as compared to Neutron, the resources will be created in VSD. In case there are more
+resources in VSD, they will be deleted from VSD.
+
+Sync will be controlled by two config parameters "enable_sync" and "sync_interval".
+If the "enable_sync" parameter is set to true, the sync will start when Neutron
+server starts and will try to sync resources. The sync will run periodically at an
+interval specified for the "sync_interval" parameter.
+
+Assumption:
+1. If the resource exists in VSD, all of its attributes are in sync with the corresponding
+Neutron resource.
+
+Alternatives
+------------
+
+None
+
+Data model impact
+-----------------
+
+None
+
+REST API impact
+---------------
+
+None
+
+Security impact
+---------------
+
+None
+
+Notifications impact
+--------------------
+
+None
+
+Other end user impact
+---------------------
+
+None
+
+Performance Impact
+------------------
+
+None
+
+Other deployer impact
+---------------------
+
+None
+
+Developer impact
+----------------
+
+None
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+ sayaji15
+
+Work Items
+----------
+
+ * Modify the nuage plugin to add sync logic
+
+Dependencies
+============
+
+None
+
+Testing
+=======
+
+Unit tests will be provided.
+
+Documentation Impact
+====================
+
+None
+
+References
+==========
+
+None