Moving requirements documentation for Danube

Moving the requirements documentation in order to comply to the
new structure for Danube.

Change-Id: Ifbf87b49ce2308d082510ca761bb7bc6479fce58
Signed-off-by: Georg Kunz <georg.kunz@ericsson.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/docs/development/requirements/use_cases/georedundancy_cells.rst b/docs/development/requirements/use_cases/georedundancy_cells.rst
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+.. This work is licensed under a Creative Commons Attribution 4.0 International License.
+.. http://creativecommons.org/licenses/by/4.0
+
+Connection between different OpenStack cells
+--------------------------------------------
+Description
+~~~~~~~~~~~
+There should be an API to manage the infrastructure networks between two
+OpenStack cells. (Note: In the Mitaka release of OpenStack cells v1 are
+considered as experimental, while cells v2 functionality is under
+implementation). Cells are considered to be problematic from maintainability
+perspective as the sub-cells are using only the internal message bus and there
+is no API (and CLI) to do maintenance actions in case of a network connectivity
+problem between the main cell and the sub cells.
+
+The following figure (:numref:`cells-architecture`) shows the architecture of
+the most relevant OpenStack components in multi cell OpenStack environment.
+
+.. figure:: images/cells-architecture.png
+    :name:  cells-architecture
+    :width: 50%
+
+The functionality behind the API depends on the underlying network providers (SDN
+controllers) and the networking setup.
+(For example OpenDaylight has an API to add new BGP neighbor.)
+
+OpenStack Neutron should provide an abstracted API for this functionality what
+calls the underlying SDN controllers API.
+
+Derived Requirements
+~~~~~~~~~~~~~~~~~~~~~
+   - Possibility to define a remote and a local endpoint
+   - As in case of cells the nova-api service is shared. It should be possible
+     to identify the cell in the API calls
+
+Northbound API / Workflow
++++++++++++++++++++++++++
+   - An infrastructure network management API is needed
+   - API call to define the remote and local infrastructure endpoints
+   - When the endpoints are created neutron is configured to use the new network.
+
+Dependencies on compute services
+++++++++++++++++++++++++++++++++
+   None.
+
+Data model objects
+++++++++++++++++++
+   - local and remote endpoint objects (Most probably IP addresses with some
+     additional properties).
+
+Current implementation
+~~~~~~~~~~~~~~~~~~~~~~
+  Current OpenStack implementation provides no way to set up the underlay
+  network connection.
+  OpenStack Tricircle project [TRICIRCLE]_
+  has plans to build up inter datacenter L2 and L3 networks.
+
+Gaps in the current solution
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  An infrastructure management API is missing from Neutron where the local and
+  remote endpoints of the underlay network could be configured.