Add Virtual IMS Core use case.

Initial draft import. Authored-By: Calum.Loudon@metaswitch.com Co-Authored-By: Stephen Gordon <sgordon@redhat.com> Change-Id: Ib53bd10dc83ceb2f9117268ee07f1712d054610e
2015-02-25 07:30:23 +02:00 · 2015-02-25 07:30:23 +02:00 · 22ba04796c
parent 7d2f1341a5
commit 22ba04796c
1 changed files with 91 additions and 0 deletions
--- a/specs/Virtual_IMS_Core.rst
+++ b/specs/Virtual_IMS_Core.rst
@ -0,0 +1,91 @@
+::
+
+This work is licensed under a Creative Commons Attribution 3.0 Unported License.
+http://creativecommons.org/licenses/by/3.0/legalcode
+
+=============================
+ Virtual IMS Core
+=============================
+
+Project Clearwater, http://www.projectclearwater.org/. An open source
+implementation of an IMS core designed to run in the cloud and be massively
+scalable. It provides SIP-based call control for voice and video as well as SIP
+based messaging apps. As an IMS core it provides P/I/S-CSCF function together
+with a BGCF and an HSS cache, and includes a WebRTC gateway providing
+interworking between WebRTC & SIP clients.
+
+TODO: Move Project Clearwater info to glossary and/or problem description.
+TODO: Generalize above.
+
+Glossary
+========
+
+* IMS -
+* SIP -
+* P/I/S-CSCF -
+* BGCF -
+* HSS -
+
+Problem description
+===================
+
+A detailed description of the problem. This should include the types of
+functions that you expect to run on OpenStack and their interactions both
+with OpenStack and with external systems.
+
+* Mainly a compute application: modest demands on storage and networking.
+* Fully HA, with no SPOFs and service continuity over software and hardware
+  failures; must be able to offer SLAs.
+* Elastically scalable by adding/removing instances under the control of the
+  NFV orchestrator.
+
+Examples
+--------
+
+In order to explain your use case, if possible, provide an example of a
+currently implemented or documented planned solution.
+
+Gaps
+----
+
+
+If you are already aware of any gaps that exist in OpenStack that
+prevent the implementation of this use case, provide them here.
+
+Affected By
+-----------
+
+If you are aware of any work in progress that will affect this use case,
+please list it here.  Include links to a spec or blueprint or bug report
+where applicable.
+
+Requirements
+============
+
+* Compute application:
+** OpenStack already provides everything needed; in particular, there are no
+   requirements for an accelerated data plane, nor for core pinning nor NUMA
+* HA:
+** implemented as a series of N+k compute pools; meeting a given SLA requires
+   being able to limit the impact of a single host failure
+** potentially a scheduler gap here: affinity/anti-affinity can be expressed
+   pair-wise between VMs, which is sufficient for a 1:1 active/passive
+   architecture, but an N+k pool needs a concept equivalent to
+   "group anti-affinity" i.e. allowing the NFV orchestrator to assign each VM
+   in a pool to one of X buckets, and requesting OpenStack to ensure no single
+   host failure can affect more than one bucket (there are other approaches
+   which achieve the same end e.g. defining a group where the scheduler ensures
+   every pair of VMs within that group are not instantiated on the same host)
+   for study whether this can be implemented using current scheduler hints
+* Elastic scaling:
+** as for compute requirements there is no gap - OpenStack already provides
+   everything needed.
+
+References
+----------
+
+* https://wiki.openstack.org/wiki/TelcoWorkingGroup/UseCases#Virtual_IMS_Core
+
+Related Use Cases
+=================
+