--- /dev/null
+===========
+Terminology
+===========
+
+Terminologies
+=============
+
+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 to the VNFs
+ as required by the Management & Orchestration functions and especially the VIM.
+ 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, which upgrades a node or a subset
+ of nodes at a time 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, which 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 piece of hardware in the NFV infrastructure that may
+ also include firmware enabling this piece of 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,
+ virtual resources are the resources on which VNFs are deployed. Examples of
+ virtual resources are: VMs, virtual switches, virtual routers, virtual disks.
+
+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 strategy, the state of the configuration and the upgrade target
+ some parts of the system may be in a more vulnerable state with respect to
+ service availbility.
+
+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.
+
+Backup
+ The term refers to data persisted to a storage, so that it can be used to
+ restore the system or a given part of it in the same state as it was when the
+ backup was created assuming a cold restart. Changes made to the system from
+ the moment the backup was created till the moment it is used to restore the
+ (sub)system are lost in the restoration process.
+
+Restore
+ The term refers to a failure handling strategy that reverts the changes
+ done, for example, by an upgrade by restoring the system from some backup
+ data. This results in the loss of any change and data persisted after the
+ backup was been taken. To recover those additional measures need to be taken
+ if necessary (e.g. rollforward).
+
+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.
+
+Abbreviations
+=============
+
+NFVI
+ The term is an abbreviation for Network Function Virtualization
+ Infrastructure; sometimes it is also referred as data plane in this
+ document. The NFVI provides the virtual resources to the virtual
+ network functions under the control of the VIM.
+
+VIM
+ The term is an abbreviation for Virtual Infrastructure Manager;
+ sometimes it is also referred as control plane in this document.
+ The VIM controls and manages the NFVI compute, network and storage
+ resources to provide the required virtual resources to the VNFs.
+
Code Review / escalator.git / blobdiff