19 files changed, 1332 insertions, 0 deletions
diff --git a/docs/00-Authors.rst b/docs/00-Authors.rst
new file mode 100644
index 0000000..fdbf61b
--- /dev/null
+++ b/docs/00-Authors.rst
@@ -0,0 +1,15 @@
+Authors:
+--------
+
+| Jie Hu (ZTE, hu.jie@zte.com.cn)
+| Qiao Fu (China Mobile, fuqiao@chinamobile.com)
+| Ulrich Kleber (Huawei, Ulrich.Kleber@huawei.com)
+| Maria Toeroe (Ericsson, maria.toeroe@ericsson.com)
+| Sama, Malla Reddy (DOCOMO, sama@docomolab-euro.com)
+| Zhong Chao (ZTE, chao.zhong@zte.com.cn)
+| Julien Zhang (ZTE, zhang.jun3g@zte.com.cn)
+| Yuri Yuan (ZTE, yuan.yue@zte.com.cn)
+| Zhipeng Huang (Huawei, huangzhipeng@huawei.com)
+| Jia Meng (ZTE, meng.jia@zte.com.cn)
+| Liyi Meng (Ericsson, liyi.meng@ericsson.com)
+| Pasi Vaananen (Stratus, pasi.vaananen@stratus.com)
+\ No newline at end of file
diff --git a/docs/01-Scope.rst b/docs/01-Scope.rst
new file mode 100644
index 0000000..5247e40
--- /dev/null
+++ b/docs/01-Scope.rst
@@ -0,0 +1,28 @@
+Scope
+-----
+
+This document describes the user requirements on the smooth upgrade
+function of the NFVI and VIM with respect to the upgrades of the OPNFV
+platform from one version to another. Smooth upgrade means that the
+upgrade results in no service outage for the end-users. This requires
+that the process of the upgrade is automatically carried out by a tool
+(code name: Escalator) with pre-configured data. The upgrade process
+includes preparation, validation, execution, monitoring and
+conclusion.
+  
+.. <MT> While it is good to have a tool for the entire upgrade process,
+   but it is a challenging task, so maybe we shouldn't require automation
+   for the entire process right away. Automation is essential at
+   execution.
+  
+.. <hujie> Maybe we can analysis information flows of the upgrade tool,
+   abstract the basic / essential actions from the tool (or tools), and
+   map them to a command set of NFVI / VIM's interfaces.
+
+The requirements are defined in a stepwise approach, i.e. in the first
+phase focusing on the upgrade of the VIM then widening the scope to the
+NFVI.
+
+The requirements may apply to different NFV functions (NFVI, or VIM, or
+both of them). They will be classified in the Appendix of this
+document.
+\ No newline at end of file
diff --git a/docs/02-Background_and_Terminologies.rst b/docs/02-Background_and_Terminologies.rst
new file mode 100644
index 0000000..36a81f2
--- /dev/null
+++ b/docs/02-Background_and_Terminologies.rst
@@ -0,0 +1,517 @@
+General Requirements Background and Terminology
+-----------------------------------------------
+
+Terminologies and definitions
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+NFVI
+  The term is an abbreviation for Network Function Virtualization
+  Infrastructure; sometimes it is also referred as data plane in this
+  document.
+
+VIM
+  The term is an abbreviation for Virtual Infrastructure Management;
+  sometimes it is also referred as control plane in this document.
+
+Operator
+  The term refers to network service providers and Virtual Network
+  Function (VNF) providers.
+
+End-User
+  The term refers to a subscriber of the Operator's services.
+
+Network Service
+  The term refers to a service provided by an Operator to its
+  End-users using a set of (virtualized) Network Functions
+
+Infrastructure Services
+  The term refers to services provided by the NFV Infrastructure and the
+  the Management & Orchestration functions to the VNFs. I.e.
+  these are the virtual resources as perceived by the VNFs.
+
+Smooth Upgrade
+  The term refers to an upgrade that results in no service outage
+  for the end-users.
+
+Rolling Upgrade
+  The term refers to an upgrade strategy that upgrades each node or
+  a subset of nodes in a wave style rolling through the data centre. It
+  is a popular upgrade strategy to maintain service availability.
+
+Parallel Universe Upgrade
+  The term refers to an upgrade strategy that creates and deploys
+  a new universe - a system with the new configuration - while the old
+  system continues running. The state of the old system is transferred
+  to the new system after sufficient testing of the new system.
+
+Infrastructure Resource Model
+  The term refers to the representation of infrastructure resources,
+  namely: the physical resources, the virtualization
+  facility resources and the virtual resources.
+
+Physical Resource
+  The term refers to a hardware pieces of the NFV infrastructure, which may
+  also include the firmware which enables the hardware.
+
+Virtual Resource
+  The term refers to a resource, which is provided as services built on top
+  of the physical resources via the virtualization facilities; in particular,
+  they are the resources on which VNF entities are deployed, e.g.
+  the VMs, virtual switches, virtual routers, virtual disks etc.
+
+Visualization Facility
+  The term refers to a resource that enables the creation
+  of virtual environments on top of the physical resources, e.g.
+  hypervisor, OpenStack, etc.
+
+Upgrade Campaign
+  The term refers to a choreography that describes how the upgrade should
+  be performed in terms of its targets (i.e. upgrade objects), the
+  steps/actions required of upgrading each, and the coordination of these
+  steps so that service availability can be maintained. It is an input to an
+  upgrade tool (Escalator) to carry out the upgrade.
+
+Upgrade Duration
+  The duration of an upgrade characterized by the time elapsed between its
+  initiation and its completion. E.g. from the moment the execution of an
+  upgrade campaign has started until it has been committed. Depending on
+  the upgrade method and its target some parts of the system may be in a more
+  vulnerable state.
+
+Outage
+  The period of time during which a given service is not provided is referred
+  as the outage of that given service. If a subsystem or the entire system
+  does not provide any service, it is the outage of the given subsystem or the
+  system. Smooth upgrade means upgrade with no outage for the user plane, i.e.
+  no VNF should experience service outage.
+
+Rollback
+  The term refers to a failure handling strategy that reverts the changes
+  done by a potentially failed upgrade execution one by one in a reverse order.
+  I.e. it is like undoing the changes done by the upgrade.
+
+Restore
+  The term refers to a failure handling strategy that reverts the changes
+  done by an upgrade by restoring the system from some backup data. This
+  results in the loss of any data persisted since the backup has been taken.
+
+Rollforward
+  The term refers to a failure handling strategy applied after a restore
+  (from a backup) opertaion to recover any loss of data persisted between
+  the time the backup has been taken and the moment it is restored. Rollforward
+  requires that data that needs to survive the restore operation is logged at
+  a location not impacted by the restore so that it can be re-applied to the
+  system after its restoration from the backup.
+
+Downgrade
+  The term refers to an upgrade in which an earlier version of the software
+  is restored through the upgrade procedure. A system can be downgraded to any
+  earlier version and the compatibility of the versions will determine the
+  applicable upgrade strategies and whether service outage can be avoided.
+  In particular any data conversion needs special attention.
+
+
+
+Upgrade Objects
+~~~~~~~~~~~~~~~
+
+Physical Resource
+^^^^^^^^^^^^^^^^^
+
+Most cloud infrastructures support the dynamic addition/removal of
+hardware. Accordingly a hardware upgrade could be done by adding the new
+piece of hardware and removing the old one. From the persepctive of smooth
+upgrade the orchestration/scheduling of this actions is the primary concern.
+Upgrading a physical resource may involve as well the upgrade of its firmware
+and/or modifying its configuration data. This may require the restart of the
+hardware.
+
+
+
+Virtual Resources
+^^^^^^^^^^^^^^^^^
+
+Addition and removal of virtual resources may be initiated by the users or be
+a result of an elasticity action. Users may also request the upgrade of their
+virtual resources using a new VM image.
+
+.. Needs to be moved to requirement section: Escalator should facilitate such an
+option and allow for a smooth upgrade.
+
+On the other hand changes in the infrastructure, namely, in the hardware and/or
+the virtualization facility resources may result in the upgrade of the virtual
+resources. For example if by some reason the hypervisor is changed and
+the current VMs cannot be migrated to the new hypervisor - they are
+incompatible - then the VMs need to be upgraded too. This is not
+something the NFVI user (i.e. VNFs ) would know about. In such cases
+smooth upgrade is essential.
+
+
+Virtualization Facility Resources
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Based on the functionality they provide, virtualization facility
+resources could be divided into computing node, networking node,
+storage node and management node.
+
+The possible upgrade objects in these nodes are addressed below:
+(Note: hardware based virtualization may be considered as virtualization
+facility resource, but from escalator perspective, it is better to
+consider it as part of the hardware upgrade. )
+
+**Computing node**
+
+1. OS Kernel
+
+2. Hypvervisor and virtual switch
+
+3. Other kernel modules, like driver
+
+4. User space software packages, like nova-compute agents and other
+   control plane programs.
+
+Updating 1 and 2 will cause the loss of virtualzation functionality of
+the compute node, which may lead to data plane services interruption
+if the virtual resource is not redudant.
+
+Updating 3 might result the same.
+
+Updating 4 might lead to control plane services interruption if not an
+HA deployment.
+
+**Networking node**
+
+1. OS kernel, optional, not all switches/routers allow the upgrade their
+   OS since it is more like a firmware than a generic OS.
+
+2. User space software package, like neutron agents and other control
+   plane programs
+
+Updating 1 if allowed will cause a node reboot and therefore leads to
+data plane service interruption if the virtual resource is not
+redundant.
+
+Updating 2 might lead to control plane services interruption if not an
+HA deployment.
+
+**Storage node**
+
+1. OS kernel, optional, not all storage nodes allow the upgrade their OS
+   since it is more like a firmware than a generic OS.
+
+2. Kernel modules
+
+3. User space software packages, control plane programs
+
+Updating 1 if allowed will cause a node reboot and therefore leads to
+data plane services interruption if the virtual resource is not
+redundant.
+
+Update 2 might result in the same.
+
+Updating 3 might lead to control plane services interruption if not an
+HA deployment.
+
+**Management node**
+
+1. OS Kernel
+
+2. Kernel modules, like driver
+
+3. User space software packages, like database, message queue and
+   control plane programs.
+
+Updating 1 will cause a node reboot and therefore leads to control
+plane services interruption if not an HA deployment. Updating 2 might
+result in the same.
+
+Updating 3 might lead to control plane services interruption if not an
+HA deployment.
+
+
+
+
+
+Upgrade Granularity
+~~~~~~~~~~~~~~~~~~~
+
+The granularity of an upgrade can be characterized from two perspective:
+- the physical dimension and
+- the software dimension
+
+
+Physical Dimension
+^^^^^^^^^^^^^^^^^^
+
+The physical dimension characterizes the number of similar upgrade objects
+targeted by the upgrade, i.e. whether it is full / partial upgrade of a
+data centre, cluster, zone.
+Because of the upgrade of a data centre or a zone, it may be divided into
+several batches. Thus there is a need for efficiency in the execution of
+upgrades of potentially huge number of upgrade objects while still maintain
+availability to fulfill the requirement of smooth upgrade.
+
+The upgrade of a cloud environment (cluster) may also
+be partial. For example, in one cloud environment running a number of
+VNFs, we may just try to upgrade one of them to check the stability and
+performance, before we upgrade all of them.
+Thus there is a need for proper organization of the artifacts associated with
+the different upgrade objects. Also the different versions should be able
+to coextist beyond the upgrade period.
+
+From this perspective special attention may be needed when upgrading
+objects that are collaborating in a redundancy schema as in this case
+different versions not only need to coexist but also collaborate. This
+puts requirement on the upgrade objects primarily. If this is not possible
+the upgrade campaign should be designed in such a way that the proper
+isolation is ensured.
+
+Software Dimension
+^^^^^^^^^^^^^^^^^^
+
+The software dimension of the upgrade characterizes the upgrade object
+type targeted and the combination in which they are upgraded together.
+
+Even though the upgrade may
+initially target only one type of upgrade object, e.g. the hypervisor
+the dependency of other upgrade objects on this initial target object may
+require their upgrade as well. I.e. the upgrades need to be combined. From this
+perspective the main concern is compatibility of the dependent and
+sponsor objects. To take into consideration of these dependencies
+they need to be described together with the version compatility information.
+Breaking dependencies is the major cause of outages during upgrades.
+
+In other cases it is more efficient to upgrade a combination of upgrade
+objects than to do it one by one. One aspect of the combination is how
+the upgrade packages can be combined, whether a new image can be created for
+them before hand or the different packages can be installed during the upgrade
+independently, but activated together.
+
+The combination of upgrade objects may span across
+layers (e.g. software stack in the host and the VM of the VNF).
+Thus, it may require additional coordination between the management layers.
+
+With respect to each upgrade object type and even stacks we can
+distingush major and minor upgrades:
+
+**Major Upgrade**
+
+Upgrades between major releases may introducing significant changes in
+function, configuration and data, such as the upgrade of OPNFV from
+Arno to Brahmaputra.
+
+**Minor Upgrade**
+
+Upgrades inside one major releases which would not leads to changing
+the structure of the platform and may not infect the schema of the
+system data.
+
+Scope of Impact
+~~~~~~~~~~~~~~~
+
+Considering availability and therefore smooth upgrade, one of the major
+concerns is the predictability and control of the outcome of the different
+upgrade operations. Ideally an upgrade can be performed without impacting any
+entity in the system, which means none of the operations change or potentially
+change the behaviour of any entity in the system in an uncotrolled manner.
+Accordingly the operations of such an upgrade can be performed any time while
+the system is running, while all the entities are online. No entity needs to be
+taken offline to avoid such adverse effects. Hence such upgrade operations
+are referred as online operations. The effects of the upgrade might be activated
+next time it is used, or may require a special activation action such as a
+restart. Note that the activation action provides more control and predictability.
+
+If an entity's behavior in the system may change due to the upgrade it may
+be better to take it offline for the time of the relevant upgrade operations.
+The main question is however considering the hosting relation of an upgrade
+object what hosted entities are impacted. Accordingly we can identify a scope
+which is impacted by taking the given upgrade object offline. The entities
+that are in the scope of impact may need to be taken offline or moved out of
+this scope i.e. migrated.
+
+If the impacted entity is in a different layer managed by another manager
+this may require coordination because taking out of service some
+infrastructure resources for the time of their upgrade which support virtual
+resources used by VNFs that should not experience outages. The hosted VNFs
+may or may not allow for the hot migration of their VMs. In case of migration
+the VMs placement policy should be considered.
+
+
+
+Upgrade duration
+~~~~~~~~~~~~~~~~
+
+As the OPNFV end-users are primarily Telecom operators, the network
+services provided by the VNFs deployed on the NFVI should meet the
+requirement of 'Carrier Grade'.::
+
+  In telecommunication, a "carrier grade" or"carrier class" refers to a
+  system, or a hardware or software component that is extremely reliable,
+  well tested and proven in its capabilities. Carrier grade systems are
+  tested and engineered to meet or exceed "five nines" high availability
+  standards, and provide very fast fault recovery through redundancy
+  (normally less than 50 milliseconds). [from wikipedia.org]
+
+"five nines" means working all the time in ONE YEAR except 5'15".
+
+::
+
+  We have learnt that a well prepared upgrade of OpenStack needs 10
+  minutes. The major time slot in the outage time is used spent on
+  synchronizing the database. [from ' Ten minutes OpenStack Upgrade? Done!
+  ' by Symantec]
+
+This 10 minutes of downtime of the OpenStack services however did not impact the
+users, i.e. the VMs running on the compute nodes. This was the outage of
+the control plane only. On the other hand with respect to the
+preparations this was a manually tailored upgrade specific to the
+particular deployment and the versions of each OpenStack service.
+
+The project targets to achieve a more generic methodology, which however
+requires that the upgrade objects fulfil certain requirements. Since
+this is only possible on the long run we target first the upgrade
+of the different VIM services from version to version.
+
+**Questions:**
+
+1. Can we manage to upgrade OPNFV in only 5 minutes?
+ 
+.. <MT> The first question is whether we have the same carrier grade
+   requirement on the control plane as on the user plane. I.e. how
+   much control plane outage we can/willing to tolerate?
+   In the above case probably if the database is only half of the size
+   we can do the upgrade in 5 minutes, but is that good? It also means
+   that if the database is twice as much then the outage is 20
+   minutes.
+   For the user plane we should go for less as with two release yearly
+   that means 10 minutes outage per year.
+
+.. <Malla> 10 minutes outage per year to the users? Plus, if we take
+   control plane into the consideration, then total outage will be
+   more than 10 minute in whole network, right?
+
+.. <MT> The control plane outage does not have to cause outage to
+   the users, but it may of course depending on the size of the system
+   as it's more likely that there's a failure that needs to be handled
+   by the control plane.
+
+2. Is it acceptable for end users ? Such as a planed service
+   interruption will lasting more than ten minutes for software
+   upgrade.
+
+.. <MT> For user plane, no it's not acceptable in case of
+   carrier-grade. The 5' 15" downtime should include unplanned and
+   planned downtimes.
+   
+.. <Malla> I go agree with Maria, it is not acceptable.
+
+3. Will any VNFs still working well when VIM is down?
+
+.. <MT> In case of OpenStack it seems yes. .:)
+
+The maximum duration of an upgrade
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The duration of an upgrade is related to and proportional with the
+scale and the complexity of the OPNFV platform as well as the
+granularity (in function and in space) of the upgrade.
+
+.. <Malla> Also, if is a partial upgrade like module upgrade, it depends
+  also on the OPNFV modules and their tight connection entities as well.
+
+.. <MT> Since the maintenance window is shrinking and becoming non-existent
+  the duration of the upgrade is secondary to the requirement of smooth upgrade.
+  But probably we want to be able to put a time constraint on each upgrade
+  during which it must complete otherwise it is considered failed and the system
+  should be rolled back. I.e. in case of automatic execution it might not be clear
+  if an upgrade is long or just hanging. The time constraints may be a function
+  of the size of the system in terms of the upgrade object(s).
+
+The maximum duration of a roll back when an upgrade is failed 
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The duration of a roll back is short than the corresponding upgrade. It
+depends on the duration of restore the software and configure data from
+pre-upgrade backup / snapshot.
+
+.. <MT> During the upgrade process two types of failure may happen:
+  In case we can recover from the failure by undoing the upgrade
+  actions it is possible to roll back the already executed part of the
+  upgrade in graceful manner introducing no more service outage than
+  what was introduced during the upgrade. Such a graceful roll back
+  requires typically the same amount of time as the executed portion of
+  the upgrade and impose minimal state/data loss.
+  
+.. <MT> Requirement: It should be possible to roll back gracefully the
+  failed upgrade of stateful services of the control plane.
+  In case we cannot recover from the failure by just undoing the
+  upgrade actions, we have to restore the upgraded entities from their
+  backed up state. In other terms the system falls back to an earlier
+  state, which is typically a faster recovery procedure than graceful
+  roll back and depending on the statefulness of the entities involved it
+  may result in significant state/data loss.
+  
+.. <MT> Two possible types of failures can happen during an upgrade
+
+.. <MT> We can recover from the failure that occurred in the upgrade process:
+  In this case, a graceful rolling back of the executed part of the
+  upgrade may be possible which would "undo" the executed part in a
+  similar fashion. Thus, such a roll back introduces no more service
+  outage during an upgrade than the executed part introduced. This
+  process typically requires the same amount of time as the executed
+  portion of the upgrade and impose minimal state/data loss.
+
+.. <MT> We cannot recover from the failure that occurred in the upgrade
+   process: In this case, the system needs to fall back to an earlier
+   consistent state by reloading this backed-up state. This is typically
+   a faster recovery procedure than the graceful roll back, but can cause
+   state/data loss. The state/data loss usually depends on the
+   statefulness of the entities whose state is restored from the backup.
+
+The maximum duration of a VNF interruption (Service outage)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Since not the entire process of a smooth upgrade will affect the VNFs,
+the duration of the VNF interruption may be shorter than the duration
+of the upgrade. In some cases, the VNF running without the control
+from of the VIM is acceptable.
+
+.. <MT> Should require explicitly that the NFVI should be able to
+  provide its services to the VNFs independent of the control plane?
+
+.. <MT> Requirement: The upgrade of the control plane must not cause
+  interruption of the NFVI services provided to the VNFs.
+
+.. <MT> With respect to carrier-grade the yearly service outage of the
+  VNF should not exceed 5' 15" regardless whether it is planned or
+  unplanned outage. Considering the HA requirements TL-9000 requires an
+  end-to-end service recovery time of 15 seconds based on which the ETSI
+  GS NFV-REL 001 V1.1.1 (2015-01) document defines three service
+  availability levels (SAL). The proposed example service recovery times
+  for these levels are:
+
+.. <MT> SAL1: 5-6 seconds
+
+.. <MT> SAL2: 10-15 seconds
+
+.. <MT> SAL3: 20-25 seconds
+
+.. <Pva> my comment was actually that the downtime metrics of the
+  underlying elements, components and services are small fraction of the
+  total E2E service availability time. No-one on the E2E service path
+  will get the whole downtime allocation (in this context it includes
+  upgrade process related outages for the services provided by VIM etc.
+  elements that are subject to upgrade process).
+  
+.. <MT> So what you are saying is that the upgrade of any entity
+  (component, service) shouldn't cause even this much service
+  interruption. This was the reason I brought these figures here as well
+  that they are posing some kind of upper-upper boundary. Ideally the
+  interruption is in the millisecond range i.e. no more than a
+  switch-over or a live migration.
+  
+.. <MT> Requirement: Any interruption caused to the VNF by the upgrade
+  of the NFVI should be in the sub-second range.
+
+.. <MT]> In the future we also need to consider the upgrade of the NFVI,
+  i.e. HW, firmware, hypervisors, host OS etc.
+\ No newline at end of file
diff --git a/docs/03-Functional_Requirements.rst b/docs/03-Functional_Requirements.rst
new file mode 100644
index 0000000..c0695bb
--- /dev/null
+++ b/docs/03-Functional_Requirements.rst
@@ -0,0 +1,240 @@
+Functional Requirements
+-----------------------
+
+Basic Actions
+~~~~~~~~~~~~~
+
+This section describes the basic functions may required by Escalator.
+
+Preparation (offline)
+^^^^^^^^^^^^^^^^^^^^^
+
+This is the design phase when the upgrade plan (or upgrade campaign) is
+being designed so that it can be executed automatically with minimal
+service outage. It may include the following work:
+
+1. Check the dependencies of the software modules and their impact,
+   backward compatibilities to figure out the appropriate upgrade method
+   and ordering.
+2. Find out if a rolling upgrade could be planned with several rolling
+   steps to avoid any service outage due to the upgrade some
+   parts/services at the same time.
+3. Collect the proper version files and check the integration for
+   upgrading.
+4. The preparation step should produce an output (i.e. upgrade
+   campaign/plan), which is executable automatically in an NFV Framework
+   and which can be validated before execution.
+
+   -  The upgrade campaign should not be referring to scalable entities
+      directly, but allow for adaptation to the system configuration and
+      state at any given moment.
+   -  The upgrade campaign should describe the ordering of the upgrade
+      of different entities so that dependencies, redundancies can be
+      maintained during the upgrade execution
+   -  The upgrade campaign should provide information about the
+      applicable recovery procedures and their ordering.
+   -  The upgrade campaign should consider information about the
+      verification/testing procedures to be performed during the upgrade
+      so that upgrade failures can be detected as soon as possible and
+      the appropriate recovery procedure can be identified and applied.
+   -  The upgrade campaign should provide information on the expected
+      execution time so that hanging execution can be identified
+   -  The upgrade campaign should indicate any point in the upgrade when
+      coordination with the users (VNFs) is required.
+
+.. <hujie> Depends on the attributes of the object being upgraded, the
+  upgrade plan may be slitted into step(s) and/or sub-plan(s), and even
+  more small sub-plans in design phase. The plan(s) or sub-plan(s) my
+  include step(s) or sub-plan(s).
+
+Validation the upgrade plan / Checking the pre-requisites of System( offline / online)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The upgrade plan should be validated before the execution by testing
+it in a test environment which is similar to the product environment.
+
+.. <MT> However it could also mean that we can identify some properties
+  that it should satisfy e.g. what operations can or cannot be executed
+  simultaneously like never take out two VMs of the same VNF.
+  
+.. <MT> Another question is if it requires that the system is in a particular
+  state when the upgrade is applied. I.e. if there's certain amount of
+  redundancy in the system, migration is enabled for VMs, when the NFVI
+  is upgraded the VIM is healthy, when the VIM is upgraded the NFVI is
+  healthy, etc.
+  
+.. <MT> I'm not sure what online validation means: Is it the validation of the
+  upgrade plan/campaign or the validation of the system that it is in a
+  state that the upgrade can be performed without too much risk?==
+
+Before the upgrade plan being executed, the system healthy of the
+online product environment should be checked and confirmed to satisfy
+the requirements which were described in the upgrade plan. The
+sysinfo, e.g. which included system alarms, performance statistics and
+diagnostic logs, will be collected and analogized. It is required to
+resolve all of the system faults or exclude the unhealthy part before
+executing the upgrade plan.
+
+
+Backup/Snapshot (online)
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+For avoid loss of data when a unsuccessful upgrade was encountered, the
+data should be back-upped and the system state snapshot should be taken
+before the execution of upgrade plan. This would be considered in the
+upgrade plan.
+
+Several backups/Snapshots may be generated and stored before the single
+steps of changes. The following data/files are required to be
+considered:
+
+1. running version files for each node.
+2. system components' configuration file and database.
+3. image and storage, if it is necessary.
+
+.. <MT> Does 3 imply VNF image and storage? I.e. VNF state and data?==
+
+.. <hujie> The following text is derived from previous "4. Negotiate
+  with the VNF if it's ready for the upgrade"
+  
+Although the upper layer, which include VNFs and VNFMs, is out of the
+scope of Escalator, but it is still recommended to let it ready for a
+smooth system upgrade. The escalator could not guarantee the safe of
+VNFs. The upper layer should have some safe guard mechanism in design,
+and ready for avoiding failure in system upgrade.
+
+Execution (online)
+^^^^^^^^^^^^^^^^^^
+
+The execution of upgrade plan should be a dynamical procedure which is
+  controlled by Escalator.
+
+.. <hujie> Revised text to be general.==
+
+1. It is required to supporting execution ether in sequence or in
+   parallel.
+2. It is required to check the result of the execution and take the
+   action according the situation and the policies in the upgrade plan.
+3. It is required to execute properly on various configurations of
+   system object. I.e. stand-alone, HA, etc.
+4. It is required to execute on the designated different parts of the
+   system. I.e. physical server, virtualized server, rack, chassis,
+   cluster, even different geographical places.
+
+Testing (online)
+^^^^^^^^^^^^^^^^
+
+The testing after upgrade the whole system or parts of system to make
+sure the upgraded system(object) is working normally.
+
+.. <hujie> Revised text to be general.
+
+1. It is recommended to run the prepared test cases to see if the
+   functionalities are available without any problem.
+2. It is recommended to check the sysinfo, e.g. system alarms,
+   performance statistics and diagnostic logs to see if there are any
+   abnormal.
+
+Restore/Roll-back (online)
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+When upgrade is failure unfortunately, a quick system restore or system
+roll-back should be taken to recovery the system and the services.
+
+.. <hujie> Revised text to be general.
+
+1. It is recommend to support system restore from backup when upgrade
+   was failed.
+2. It is recommend to support graceful roll-back with reverse order
+   steps if possible.
+
+Monitoring (online)
+^^^^^^^^^^^^^^^^^^^
+
+Escalator should continually monitor the process of upgrade. It is
+keeping update status of each module, each node, each cluster into a
+status table during upgrade.
+
+.. <hujie> Revised text to be general.
+
+1. It is required to collect the status of every objects being upgraded
+   and sending abnormal alarms during the upgrade.
+2. It is recommend to reuse the existing monitoring system, like alarm.
+3. It is recommend to support pro-actively query.
+4. It is recommend to support passively wait for notification.
+
+**Two possible ways for monitoring:**
+
+**Pro-Actively Query** requires NFVI/VIM provides proper API or CLI
+interface. If Escalator serves as a service, it should pass on these
+interfaces.
+
+**Passively Wait for Notification** requires Escalator provides
+callback interface, which could be used by NFVI/VIM systems or upgrade
+agent to send back notification.
+
+.. <hujie> I am not sure why not to subscribe the notification.
+
+Logging (online)
+^^^^^^^^^^^^^^^^
+
+Record the information generated by escalator into log files. The log
+file is used for manual diagnostic of exceptions.
+
+1. It is required to support logging.
+2. It is recommended to include time stamp, object id, action name,
+   error code, etc.
+
+Administrative Control (online)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Administrative Control is used for control the privilege to start any
+escalator's actions for avoiding unauthorized operations.
+
+#. It is required to support administrative control mechanism
+#. It is recommend to reuse the system's own secure system.
+#. It is required to avoid conflicts when the system's own secure system
+   being upgraded.
+
+Requirements on Object being upgraded
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. <hujie> We can develop BPs in future from requirements of this section and
+  gap analysis for upper stream projects
+  
+Escalator focus on smooth upgrade. In practical implementation, it
+might be combined with installer/deplorer, or act as an independent
+tool/service. In either way, it requires targeting systems(NFVI and
+VIM) are developed/deployed in a way that Escalator could perform
+upgrade on them.
+
+On NFVI system, live-migration is likely used to maintain availability
+because OPNFV would like to make HA transparent from end user. This
+requires VIM system being able to put compute node into maintenance mode
+and then isolated from normal service. Otherwise, new NFVI instances
+might risk at being schedule into the upgrading node.
+
+On VIM system, availability is likely achieved by redundancy. This
+impose less requirements on system/services being upgrade (see PVA
+comments in early version). However, there should be a way to put the
+target system into standby mode. Because starting upgrade on the
+master node in a cluster is likely a bad idea.
+
+.. <hujie>Revised text to be general.
+
+1. It is required for NFVI/VIM to support **service handover** mechanism
+   that minimize interruption to 0.001%(i.e. 99.999% service
+   availability). Possible implementations are live-migration, redundant
+   deployment, etc, (Note: for VIM, interruption could be less
+   restrictive)
+   
+2. It is required for NFVI/VIM to restore the early version in a efficient
+   way, such as **snapshot**.
+   
+3. It is required for NFVI/VIM to **migration data** efficiently between
+   base and upgraded system.
+
+4. It is recommend for NFV/VIM's interface to support upgrade
+   orchestration, e.g. reading/setting system state.
+
+
diff --git a/docs/04-Use_Cases_and_Scenarios.rst b/docs/04-Use_Cases_and_Scenarios.rst
new file mode 100644
index 0000000..ee9b488
--- /dev/null
+++ b/docs/04-Use_Cases_and_Scenarios.rst
@@ -0,0 +1,211 @@
+Use Cases and Scenarios
+-----------------------
+
+This section describes the use cases and scenarios to verify the
+requirements of Escalator.
+
+Scenarios
+~~~~~~~~~
+1. Upgrade a system with HA configuration
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+A HA configuration system is very popular in the operator's data centre.
+It is a typical product environment. It is always running 7\*24 with VNFs
+running on it to provide services to the end users.
+
+
+2. Upgrade a system with non-HA configuration
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+A non-HA configuration system is normally deployed for experimental or
+development usages, such as a Vagrant/VM environment.
+
+Escalator supports the upgrade in this scenario, but it does not guarantee a
+smooth upgrade.
+
+Use cases
+~~~~~~~~~
+Use case #1: Smooth upgrade in a HA configuration
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+For a system with HA configuration, the operator can use Escalator to
+smooth-upgrade  NFVI/VIM components into a new version without any service
+outage.
+
+When a compute node being upgraded, the VMs on the node may need to be migrated
+to other compute nodes to avoid service outage, so it is requred that there are
+enough redundant resources to migrate VMs on this compute node.
+
+Before upgrade, the operator can use Escalator to check whether smooth upgrade
+conditions are all satisfied. These conditions include whether there are enough
+idle resources to migrate VMs during updrading, and whether the new version is
+compatible with the current one, etc. If there are some conditions not
+satisfied, Escalator will show them. Escalator can also provide the solutions if
+there is any, such as the number and configuration of spare compute nodes which
+are needed.
+
+When upgrade starts, Escalator will also automatically check whether smooth
+upgrade conditions are all satisfied. If some smooth upgrade conditions are not
+satisfied, Escalator will show the failure of smooth upgrade.
+
+- Pre-Conditions
+
+  1. The system is running as normal.
+  2. The VNFs are providing services as usual.
+
+- Upgrading steps
+
+  1. The VNFs are continually providing services during the upgrade.
+  2. The operator successfully logged in the GUI of Escalator to select the
+     software packages including Linux OS, Hypervisor, OpenStack, ODL and other
+     OPNFV components, ect. (All or part of components could be selected.)
+  3. Select the nodes to be upgraded. i.e. controller node, network node,
+     storage node and compute node, etc.
+  4. Select "Disable Scale-up". It will limit the scale-up operation when
+     upgrade is in progress to prevent failures due to the shortage of
+     resources.
+  5. Select "Check Smooth Upgrade Conditions". If Escalator shows that there are
+     some conditions not satisfied, try to resolve them according to the
+     solutions provided.
+  6. Select "Smooth Upgrade", then apply the upgrade operation.
+  7. Select "Restore Scale-up" after the upgrade. It will restore scale-up to
+     the original enabled/disabled state before upgrade.
+
+- Post-Conditions
+
+  1. The system is upgraded successfully.
+  2. There is no service outage during the upgrade.
+  3. The VNFs are providing services as usual after the upgrade.
+
+Use case #2: Roll-back after a failed smooth upgrade in a HA configuration
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+For a system with HA configuration, if the upgrade fails when the operator is
+smooth-upgrading NFVI/VIM components into a new version using Escalator, the
+operator can roll-back the system without any service outage.
+
+- Pre-Conditions
+
+  1. The system is running as normal.
+  2. The VNFs are providing services as usual.
+  3. Scale-up operation is disabled.
+  4. Smooth upgrade failed.
+
+- Roll-back steps
+
+  1. Escalator concludes that the upgrade has failed and provides the operator
+     with the reason.
+  2. Select the "Roll-back" operation.
+  3. If the roll-back is successful, go to step 4, otherwise the operator can
+     select "Restore Backup" to restore the system from the backup data.
+  4. Select "Restore Scale-up" after the roll-back. It will restore scale-up to
+     the original enabled/disabled state before upgrade.
+
+- Post-Conditions
+
+  1. The system is rolled-back successfully when the upgrade failed.
+  2. There is no service outage during the roll-back.
+  3. The VNFs are providing services as usual after the roll-back.
+
+Use case #3: Roll-back after a successful smooth upgrade in a HA configuration
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+When a smooth upgrade in a HA configuration is successful, the operator may want
+to roll-back for some reasons, such as performance issues.
+Escalator supports roll-back after a successful smooth upgrade without any
+service outage.
+
+- Pre-Conditions
+
+  1. The system is running as normal.
+  2. The VNFs are providing services as usual.
+  3. Smooth upgrade succeeded.
+
+- Roll-back steps
+
+  1. Select "Disable Scale-up". It will limit the scale-up operation when roll-
+     back is in progress to prevent failures due to the shortage of resources.
+  2. Select "Check Smooth Roll-back Conditions". If Escalator shows that there
+     are some conditions not satisfied, try to resolve them according to the
+     solutions provided.
+  3. Select "Roll-back", then apply the roll-back operation.
+  4. If the roll-back is successful, go to step 5, otherwise the operator can
+     select "Restore Backup" to restore the system from the backup data.
+  5. Select "Restore Scale-up" after the roll-back. It will restore scale-up to
+     the original enabled/disabled state before roll-back.
+
+- Post-Conditions
+
+  1. The system is rolled-back successfully.
+  2. There is no service outage during the roll-back.
+  3. The VNFs are providing services as usual after the roll-back.
+
+Use case #4: Non-smooth upgrade in a non-HA/HA configuration
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+For a system with non-HA configuration, the operator can also use Escalator to
+upgrade  NFVI/VIM components into a new version. In this case, the upgrade may
+result in service outage. In other words, the upgrade is non-smooth.
+For a system with HA configuration, if the service outage is acceptable or
+inevitable, the operator can also use Escalator to non-smoothly upgrade the
+system.
+
+- Pre-Conditions
+
+  1. The system is running as normal.
+
+- Upgrading steps
+
+  1. The operator successfully logged in the GUI of Escalator to select the
+     software packages including Linux OS, Hypervisor, OpenStack, ODL and other
+     OPNFV components, ect. (All or part of components could be selected.)
+  2. Select the nodes to be upgraded. i.e. controller node, network node,
+     storage node and compute node, etc.
+  3. Select "Non-Smooth Upgrade", then apply the upgrade operation.
+
+- Post-Conditions
+
+  1. The system is upgraded successfully.
+
+Use case #5: Roll-back after a failed non-smooth upgrade in a non-HA/HA configuration
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+For a system with non-HA/HA configuration, if the upgrade fails when the
+operator is non-smoothly upgrading NFVI/VIM components into a new version using
+Escalator, the operator can roll-back the system. In this case, the roll-back
+may result in service outage.
+
+- Pre-Conditions
+
+  1. The system is running as normal.
+  2. Non-smooth upgrade failed.
+
+- Roll-back steps
+
+  1. Escalator concludes that the upgrade has failed and provides the operator
+     with the reason.
+  2. Select the "Roll-back" operation.
+  3. If the roll-back fails, the operator can select "Restore Backup" to restore
+     the system from the backup data.
+
+- Post-Conditions
+
+  1. The system is rolled-back successfully when the upgrade failed.
+
+Use case #6: Roll-back after a successful non-smooth upgrade in a non-HA/HA configuration
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+When a non-smooth upgrade in a non-HA/HA configuration is successful, the
+operator may want to roll-back for some reasons, such as performance issues.
+Escalator supports roll-back after a successful non-smooth upgrade. In this
+case,the roll-back may result in service outage.
+
+- Pre-Conditions
+
+  1. The system is running as normal.
+  2. Non-smooth upgrade succeeded.
+
+- Roll-back steps
+
+  1. Select the "Roll-back" operation.
+  2. If the roll-back fails, the operator can select "Restore Backup" to restore
+     the system from the backup data.
+
+- Post-Conditions
+
+  1. The system is rolled-back successfully when the upgrade failed.
+
diff --git a/docs/05-Reference_Architecture.rst b/docs/05-Reference_Architecture.rst
new file mode 100644
index 0000000..4d5a64f
--- /dev/null
+++ b/docs/05-Reference_Architecture.rst
@@ -0,0 +1,83 @@
+Reference Architecture
+----------------------
+
+This section describes the reference architecture, the function blocks,
+and the function entities of Escalator for the reader to well understand how
+the basic functions to be organized.
+
+1. Upgrade Scope
+~~~~~~~~~~~~~~~~
+Upgrade objects described in this document are software programs covered by
+red box in the picture below which includes: VIM and NFVI.
+The target of the upgrade is to reduce the impact on the applications in the
+blue box below as much as possible.
+Note that this upgrade process does not take into consideration the effects
+of Vi-Vnfm and Or-Vi. In other words, the unserviceability of the two
+interfaces during upgrade can  be accepted.
+
+.. figure:: images/figure1.png
+   :name: figure1
+   :width: 100%
+
+The software stack on each node is generally as shown in the table below.
+
+.. figure:: images/figure2.png
+   :name: figure2
+   :width: 100%
+
+Because the control node upgrade will not affect the business in the blue box,
+this scheme focuses on upgrading of compute nodes.
+
+2. Precondition of Upgrade
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+2.1 The environmental requirements
+1.  System is running normally. If there are any faults before the upgrade, it
+is difficult to distinguish between upgrade introduced and the environment
+itself.
+2.  The environment should have the redundant resources. Because the upgrade
+process is based on the business migration, in the absence of resource
+redundancy,it is impossible to realize the business migration, as well as to
+achieve a smooth upgrade.
+
+Resource redundancy in two levels:
+1)  NFVI level: This level is mainly the compute nodes resource redundancy.
+During the upgrade, the virtual machine on business can be migrated to another
+free compute node.
+2)  VNF level: This level depends on backup mechanism in VNF, such as:
+active-standby, load balance. In this case, as long as business of the target
+node on VMs is migrated to other free nodes, the migration of VM might not be
+necessary.
+
+The way of redundancy to be used is subject to the specific environment.
+Generally speaking, the impact of using NFVI redundancy on the VMs is larger
+than the rearrangement of the business on VNF level.
+
+2.2 The demand for version
+This is primarily a compatibility requirement. You can refer to Linux/Python
+Compatible Semantic Versioning 3.0.0:
+
+Given a version number MAJOR.MINOR.PATCH, increment the:
+1.  MAJOR version when you make incompatible API changes,
+2.  MINOR version when you add functionality in a backwards-compatible manner,
+3.  PATCH version when you make backwards-compatible bug fixes.
+
+The upgrade process needs to use some interfaces which require these
+interfaces to be backward compatible. Refer to "Interface" chapter for details.
+
+3.Upgrade related modules in VIM
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Upgrade operations are initiated by the user through the VIM. For VIM, upgrade
+management mainly contains the object:
+**Upgrade Manager**:Mainly responsible for upgrading process control. Physical
+nodes information of each node is saved in upgrade manager.
+**VIM Interface**:Mainly responsible for the external interface, include
+Vi-Vnfm, Or-Vi. This module stores VNFO and VNFM external information such as
+address and authentication.
+**Cloud Manager**:Mainly responsible for virtualization resources management,
+which might be considered made up of Openstack and SDN control node.
+**System Support**:Provide the upper software running environment, including:
+OS, HA, etc. To upgrade the upper software is based on this module.
+
+.. figure:: images/figure3.png
+   :name: figure3
+   :width: 100%
+\ No newline at end of file
diff --git a/docs/06-Information_Flows.rst b/docs/06-Information_Flows.rst
new file mode 100644
index 0000000..641b59b
--- /dev/null
+++ b/docs/06-Information_Flows.rst
@@ -0,0 +1,56 @@
+Information Flows
+-----------------
+
+This section describes the information flows among the function
+entities when Escalator is in actions.
+
+1. Upgrade process of Compute nodes
+
+1.1 consider VIM as a whole
+
+.. figure:: images/figure4.png
+   :name: figure4
+   :width: 100%
+
+process is:
+1. Operators add new version files on the VIM,initiate the upgrade.
+2. VIM chooses some compute nodes as the upgrade target nodes, and set them
+into maintenance mode. VIM queries the list of running VMs on target nodes.
+3. VIM notice VNFM corresponding to  the virtual machine, to migrate the
+business.
+4. VNFM migrates the business. If the business is in active of active-standby
+mode, it will initiate switch-over. If the business is in loading balance mode,
+it will move the business to other node.
+5. After VNFM moves business, it notifies the VIM.
+6. VIM judges whether the business on the target VM has all been moved. If
+not, VIM migrates the VM with business loaded to other free nodes. Then VIM
+upgrades the target computer nodes. After upgrade, VIM set the target compute
+nodes into normal nodes.
+7. If there are computer nodes remained to be upgraded, goto step 2.
+
+4.2 from inside VIM
+
+.. figure:: images/figure5.png
+   :name: figure5
+   :width: 100%
+
+.. figure:: images/figure6.png
+   :name: figure6
+   :width: 100%
+
+process is:
+1. Upgrade manager receives user operation commands. Add new version files.
+Upgrade is began.
+2. Upgrade Manager selects compute node A to Upgrade. Query list of the VMs
+running the compute nodes A to the Cloud Manager, and set the node to
+maintenance mode, that is to say creation or migration of new VM on this node
+is impossible anymore.
+3. Upgrade Manager notifies VNFM compute node A  into maintenance mode by VIM
+interface, temporarily disabling the inserting of business, and business on
+compute node A need move to the other available compute nodes.
+4. When receives the VNFM reply, or waited for a timeout, Upgrade Manager
+notifies the system support on compute node A to do software upgrade.
+5. After upgraded, Upgrade Manager removes maintenance mode for the compute
+node A.
+6. Upgrade Manager claims VNFM computing nodes A available.
+7. Select computer node B to upgrade
+\ No newline at end of file
diff --git a/docs/07-Interfaces_and_Files.rst b/docs/07-Interfaces_and_Files.rst
new file mode 100644
index 0000000..87f916e
--- /dev/null
+++ b/docs/07-Interfaces_and_Files.rst
@@ -0,0 +1,27 @@
+Interfaces and Files
+--------------------
+
+This section describes the required interfaces and files of Escalator.
+
+
+CLI Interface
+~~~~~~~~~~~~~~~~
+
+This section describes CLI of Escalator. 
+
+RESTful API
+~~~~~~~~~~~
+
+This section describes the API of Escalator for developer.
+
+Configuration File
+~~~~~~~~~~~~~~~~~~
+
+This section will suggest a format of the configuration files and how to
+deal with it.
+
+Log File
+~~~~~~~~
+
+This section will suggest a format of the log files and how to deal with
+it.
+\ No newline at end of file
diff --git a/docs/08-Requirements_from_other_OPNFV_Project.rst b/docs/08-Requirements_from_other_OPNFV_Project.rst
new file mode 100644
index 0000000..62e611f
--- /dev/null
+++ b/docs/08-Requirements_from_other_OPNFV_Project.rst
@@ -0,0 +1,40 @@
+Requirements from other OPNFV projects
+--------------------------------------
+
+We have created a questionnaire_ for collecting other projects requirements.
+Please advertise it.
+
+.. _questionnaire: https://docs.google.com/forms/d/11o1mt15zcq0WBtXYK0n6lKF8XuIzQTwvv8ePTjmcoF0/viewform?usp=send_form
+  
+
+
+Doctor Project
+~~~~~~~~~~~~~~
+
+.. <Malla> This scenario could be out of scope in Escalator project, but
+  having the option to support this should be better to align with
+  Doctor requirements.
+  
+The scope of Doctor project also covers maintenance scenario in which
+
+1. The VIM administrator requests host maintenance to VIM.
+
+2. VIM will notify it to consumer such as VNFM to trigger application level
+   migration or switching active-standby nodes.
+
+3. VIM waits response from the consumer for a short while.
+
+-  VIM should send out notification of VM migration to consumer (VNFM)
+   as abstracted message like "maintenance".
+
+-  VIM could wait VM migration until it receives "VM ready to
+   maintenance" message from the owner (VNFM)
+
+HA Project
+~~~~~~~~~~
+
+Multi-site Project
+~~~~~~~~~~~~~~~~~~
+
+-  Escalator upgrade one site should at least not lead to the other site
+   API token validation failed.
diff --git a/docs/09-Reference.rst b/docs/09-Reference.rst
new file mode 100644
index 0000000..0b5ff17
--- /dev/null
+++ b/docs/09-Reference.rst
@@ -0,0 +1,17 @@
+Reference
+---------
+
+[1] ETSI GS NFV 002 (V1.1.1): “Architectural Framework”
+
+[2] ETSI GS NFV 003 (V1.1.1): "Terminology for Main Concepts in NFV"
+
+[3] ETSI GS NFV-SWA001:“Virtual Network Function Architecture”
+
+[4] ETSI GS NFV-MAN001:“Management and Orchestration”
+
+[5] ETSI GS NFV-REL001:"Resiliency Requirements"
+
+[6] QuEST Forum TL-9000:"Quality Management System Requirement
+Handbook"
+
+[7] Service Availability Forum AIS:"Software Management Framework"
diff --git a/docs/10-Useful_Working_Drafts_of_ETSI_NFV.rst b/docs/10-Useful_Working_Drafts_of_ETSI_NFV.rst
new file mode 100644
index 0000000..5c2195b
--- /dev/null
+++ b/docs/10-Useful_Working_Drafts_of_ETSI_NFV.rst
@@ -0,0 +1,11 @@
+Useful Working Drafts of ETSI NFV
+---------------------------------
+
+Access them with your own ETSI account, please DO NOT disclose the
+content.
+
+[1] Migrate Virtualised Compute Resource operation @ 7.3.1.8
+ftp://docbox.etsi.org/ISG/NFV/Open/Drafts/IFA005_Or-Vi_ref_point_Spec/NFV-IFA005v070.zip
+
+[2] Reliability issues during NFV Software upgrade and improvement mechanisms @ 8
+ftp://@docbox.etsi.org/ISG/NFV/Open/Drafts/REL003_E2E_reliability_models/NFV-REL003v030.zip
diff --git a/docs/A1-Appendix.rst b/docs/A1-Appendix.rst
new file mode 100644
index 0000000..85f0717
--- /dev/null
+++ b/docs/A1-Appendix.rst
@@ -0,0 +1,49 @@
+Appendix
+--------
+
+A.1 Impact Analysis
+~~~~~~~~~~~~~~~~~~~
+
+Upgrading the different software modules may cause different impact on
+the availability of the infrastructure resources and even on the service
+continuity of the vNFs.
+
+**Software modules in the computing nodes**
+
+#. Host OS patch
+
+#. Hypervisor, such as KVM, QEMU, XEN, libvirt
+#. Openstack agent in computing nodes (like Nova agent, Ceilometer
+   agent...)
+   
+.. <MT> As SW module, we should list the host OS and maybe its
+   drivers as well. From upgrade perspective do we limit host OS
+   upgrades to patches only?
+
+**Software modules in network nodes**
+
+#. Neutron L2/L3 agent
+#. OVS, SR-IOV Driver
+
+**Software modules storage nodes**
+
+#. Ceph
+
+The table below analyses such an impact - considering a single instance
+of each software module - from the following aspects:
+
+-  the function which will be lost during upgrade,
+-  the duration of the loss of this specific function,
+-  if this causes the loss of the vNF function,
+-  if it causes incompatibility in the different parts of the software,
+-  what should be backed up before the upgrade,
+-  the duration of restoration time if the upgrade fails
+
+These values provided come from internal testing and based on some
+assumptions, they may vary depending on the deployment techniques.
+Please feel free to add if you find more efficient values during your
+testing.
+
+https://wiki.opnfv.org/_media/upgrade_analysis_v0.5.xlsx
+
+Note that no redundancy of the software modules is considered in the table.
diff --git a/docs/images/figure1.png b/docs/images/figure1.png
new file mode 100644
index 0000000..da48655
--- /dev/null
+++ b/docs/images/figure1.png
diff --git a/docs/images/figure2.png b/docs/images/figure2.png
new file mode 100644
index 0000000..38346de
--- /dev/null
+++ b/docs/images/figure2.png
diff --git a/docs/images/figure3.png b/docs/images/figure3.png
new file mode 100644
index 0000000..70d16c7
--- /dev/null
+++ b/docs/images/figure3.png
diff --git a/docs/images/figure4.png b/docs/images/figure4.png
new file mode 100644
index 0000000..e74e24b
--- /dev/null
+++ b/docs/images/figure4.png
diff --git a/docs/images/figure5.png b/docs/images/figure5.png
new file mode 100644
index 0000000..a49955d
--- /dev/null
+++ b/docs/images/figure5.png
diff --git a/docs/images/figure6.png b/docs/images/figure6.png
new file mode 100644
index 0000000..efe7d6f
--- /dev/null
+++ b/docs/images/figure6.png
diff --git a/docs/index.rst b/docs/index.rst
new file mode 100644
index 0000000..1ae82e1
--- /dev/null
+++ b/docs/index.rst
@@ -0,0 +1,38 @@
+.. OPNFV Release Engineering documentation, created by
+   sphinx-quickstart on Tue Jun  9 19:12:31 2015.
+   You can adapt this file completely to your liking, but it should at least
+   contain the root `toctree` directive.
+
+.. image:: etc/opnfv-logo.png
+  :height: 40
+  :width: 200
+  :alt: OPNFV
+  :align: left
+
+ESCALATOR
+=======================================
+
+Contents:
+
+.. toctree::
+   :maxdepth: 4
+   :titlesonly:
+
+   00-Authors.rst
+   01-Scope.rst
+   02-Background_and_Terminologies.rst
+   03-Functional_Requirements.rst
+   04-Use_Cases_and_Scenarios.rst
+   05-Reference_Architecture.rst
+   06-Information_Flows.rst
+   07-Interfaces_and_Files.rst
+   08-Requirements_from_other_OPNFV_Project.rst
+   09-Reference.rst
+   10-Useful_Working_Drafts_of_ETSI_NFV.rst
+   A1-Appendix.rst
+
+* :ref:`search`
+
+Revision: _sha1_
+
+Build date: |today|