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Network Working Group                                           A. Galis
Internet-Draft                                 University College London
Intended Status: Standards Track                            K. Makhijani
Expires: May 5, 2018                                               D. Yu
                                                                  B. Liu
                                                     Huawei Technologies
                                                        November 5, 2017


                      Autonomic Slice Networking
            draft-galis-anima-autonomic-slice-networking-03

Abstract

   This document describes the technical requirements and the related
   reference model for the intercommunication and coordination among
   devices in Autonomic Slicing Networking.  The goal is to define how
   the various elements in a network slicing context work and
   orchestrate together, to describe their interfaces and relations.
   While the document is written as generally as possible, the initial
   solutions are limited to the chartered scope of the WG.



Status of this Memo

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   This Internet-Draft will expire on May 5, 2018.

Copyright Notice




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   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
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   described in the Simplified BSD License.

Table of Contents

   1  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  The Network Slicing Overall View . . . . . . . . . . . . . . .  3
     2.1.  Key Terms and Context  . . . . . . . . . . . . . . . . . .  3
     2.2.  High Level Requirements  . . . . . . . . . . . . . . . . .  6
   3.  Autonomic Slice Networking . . . . . . . . . . . . . . . . . .  8
   4.  Autonomic Inter-Slice Orchestration  . . . . . . . . . . . . . 10
   5. GRASP Resource Reservation / Release Messages flow  . . . . . . 11
   6.  The Autonomic Network Slicing Element  . . . . . . . . . . . . 12
   7.  The Autonomic Slice Networking Infrastructure  . . . . . . . . 14
     7.1.  Signaling Between Autonomic Slice Element Managers . . . . 14
     7.2.  The Autonomic Control Plane  . . . . . . . . . . . . . . . 16
     7.3.  Naming & Addressing  . . . . . . . . . . . . . . . . . . . 16
     7.4.  Discovery  . . . . . . . . . . . . . . . . . . . . . . . . 16
     7.5.  Routing  . . . . . . . . . . . . . . . . . . . . . . . . . 16
   8.  Security and Trust Infrastructure  . . . . . . . . . . . . . . 16
     8.1.  Public Key Infrastructure  . . . . . . . . . . . . . . . . 16
     8.2.  Domain Certificate . . . . . . . . . . . . . . . . . . . . 17
   9.  Cross-Domain Functionality . . . . . . . . . . . . . . . . . . 17
   10.  Autonomic Service Agents (ASA)  . . . . . . . . . . . . . . . 17
   11.  Management and Programmability  . . . . . . . . . . . . . . . 17
     11.1.  How a Slice Network Is Managed  . . . . . . . . . . . . . 17
     11.2.  Intent  . . . . . . . . . . . . . . . . . . . . . . . . . 18
     11.3.  Control Loops . . . . . . . . . . . . . . . . . . . . . . 18
     11.4.  APIs  . . . . . . . . . . . . . . . . . . . . . . . . . . 18
       11.4.1.  Slice Control APIs  . . . . . . . . . . . . . . . . . 18
       11.4.2.  Service Agent - Device APIs . . . . . . . . . . . . . 18
       11.4.3.  Service Agent - Port APIs . . . . . . . . . . . . . . 18
       11.4.4.  Service Agent - Link APIs . . . . . . . . . . . . . . 19
     11.5.  Relationship with MANO  . . . . . . . . . . . . . . . . . 19
   12.  Security Considerations . . . . . . . . . . . . . . . . . . . 19
     12.1.  Threat Analysis . . . . . . . . . . . . . . . . . . . . . 19
     12.2.  Security Mechanisms . . . . . . . . . . . . . . . . . . . 19
   13.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19



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   14.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . 19
   14.  References  . . . . . . . . . . . . . . . . . . . . . . . . . 19
     14.1.  Normative References  . . . . . . . . . . . . . . . . . . 19
     14.2.  Informative References  . . . . . . . . . . . . . . . . . 20
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22


1  Introduction

   The document "Autonomic Networking - Definitions and Design Goals"
   [RFC7575] explains the fundamental concepts behind Autonomic
   Networking, and defines the relevant terms in this space, as well as
   a high level reference model.  This document defines this reference
   model with more detail, to allow for functional and protocol
   specifications to be developed in an architecturally consistent, non-
   overlapping manner.  While the document is written as generally as
   possible, the initial solutions are limited to the chartered scope of
   the WG.

   Most networks will run with some autonomic functions for the full
   networks or for a group of nodes [RFC7576] or for a group of slice
   networks while the rest of the network is traditionally managed.

   The goal of this document is to focus on the autonomic slicing
   networking.  [RFC7575] is focusing on fully or partially autonomic
   nodes or networks.

   The proposed revised ANIMA reference model allows for this hybrid
   approach across all such capabilities. It enhances [ASN].

   This is a living document and will evolve with the technical
   solutions developed in the ANIMA WG.  Sections marked with (*) do not
   represent current charter items.

   While this document must give a long term architectural view, not all
   functions will be standardized at the same time.

2.  The Network Slicing Overall View

2.1.  Key Terms and Context


   A number of slice definitions were used in the last 10 years in
   distributed and federated testbed research [GENI], future internet
   research [ChinaCom09] and more recently in the context of 5G research
   [NGMN], [ONF], [IMT2020], [NGS-3GPP]. Such definitions converge
   towards NS as group of components: Service Instance, Network Slice
   Instance, Resources and Slice Element Manager



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   In this draft we are using the following terms:

   Logical resource - An independently manageable partition of a
   physical resource, which inherits the same characteristics as the
   physical resource and whose capability is bound to the capability of
   the physical resource.  It is dedicated to a Network Function or
   shared between a set of Network Functions.

   Virtual resource - An abstraction of a physical or logical resource,
   which may have different characteristics from that resource, and
   whose capability may not be bound to the capability of that resource

   Network Function (NF) - A processing function in a network. It
   includes but is not limited to network nodes functionality, e.g.
   session management, mobility management, switching, routing
   functions, which has defined functional behaviour and interfaces.
   Network functions can be implemented as a network node on a dedicated
   hardware or as a virtualized software functions. Data, Control,
   Management, Orchestration planes functions are Network Functions.

   Virtual Network Function (VNF) - A network function whose functional
   software is decoupled from hardware. One or more virtual machines
   running different software and processes on top of industry-standard
   high-volume servers, switches and storage, or cloud computing
   infrastructure, and capable of implementing network functions
   traditionally implemented via custom hardware appliances and middle.
   boxes (e.g. router, NAT, firewall, load balancer, etc.) Network
   Slicing (NS) refers to a managed group of subsets of resources,
   network functions / network virtual functions at the data, control,
   management/orchestration planes and services at a given time. Network
   slice is programmable and has the ability to expose its capabilities.
   The behaviour of the network slice realized via network slice
   instance(s). Network resources include connectivity, compute, and
   storage resources.

   Network Slicing is end-to-end concept covering the radio and non-
   radio networks inclusive of access, core and edge / enterprise
   networks.  It enables the concurrent deployment of multiple logical,
   self-contained and independent shared or partitioned networks on a
   common infrastructure platform

   Network slicing represents logically or physically isolated groups of
   network resources and network function/virtual network functions
   configurations separating its behavior from the underlying physical
   network.

   Network Slice Instance - An activated network slice. It is created
   based on network template. A set of managed run-time network



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   functions, and resources to run these network functions, forming a
   complete instantiated logical network to meet certain network
   characteristics required by the service instance(s). It provides the
   network characteristics that are required by a service instance. A
   network slice instance may also be shared across multiple service
   instances provided by the network operator.

   From a business point of view, a slice includes combination of all
   relevant network resources / functions / assets required to fulfill a
   specific business case or service, including OSS, BSS and DevOps
   processes.

   From the network infrastructure point of view, slicing instances
   require the partitioning and assignment of a set of resources that
   can be used in an isolated, disjunctive or non- disjunctive manner.

   Examples of physical or virtual resources to be shared or partitioned
   would include: bandwidth on a network link, forwarding tables in a
   network element (switch, router), processing capacity of servers,
   processing capacity of network or network clouds elements [SLICING].
   As such slice instances would contain:

    (i)   a combination/group of the above resources which can act as a
          network,
    (ii)  appropriate resource abstractions,
    (iii) capability exposure of abstract resources towards service and
          management clients that are needed for the operation of slices

   The capability exposure creates an abstraction of physical network
   devices that would provide information and information models
   allowing operators to manipulate the network resources. By utilizing
   open programmable network interfaces, it would enable access to
   control layer by customer interfaces and applications.

   The establishment of slices is both business-driven (i.e. slices are
   in support for different types and service characteristics and
   business cases) and technology-driven as slice is a grouping of
   physical or virtual) resources (network, compute, storage) which can
   act as a sub network and/or a cloud.  A slice can accommodate service
   components and network functions (physical or virtual) in all network
   segments: access, core and edge / enterprise networks.

   A complete slice is composed of not only various network functions
   which are based on virtual machines at C-RAN and C-Core, but also
   transport network resources that can be assigned to the slice at
   radio access/transport network.  Different future businesses require
   different throughput, delay and mobility, and some businesses need
   very high throughput or/and low delay.



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2.2.  High Level Requirements

   Slice creation: management plane create virtual or physical network
   functions and connects them as appropriate and instantiate them in
   the slice, which is a subnetworks.

   The instance of slice management then takes over the management and
   operations of all the (virtualised) network functions and network
   programmability functions assigned to the slice, and (re-)configure
   them as appropriate to provide the end-to-end service.

   A complete slice is composed of not only various network functions
   which are based on virtual machines at C-RAN and C-Core, but also
   transport network resources that can be assigned to the slice at
   radio access/transport network.  Different future businesses require
   different throughput, delay and mobility, and some businesses need
   very high throughput or/and low delay.  Transport network shall
   provide QoS isolation, flexible network operation and management, and
   improve network utilization among different business.

    (1) Separation from partition of the physical network: Network
        slicing represents logically or physically isolated groups of
        network resources and network function/virtual network functions
        configurations separating its behavior from the underlying
        physical network.

    (2) QoS Isolation: Although traditional VPN technology can provide
        physical network resource isolation across multiple network
        segments, it is deemed far less capable of supporting QoS hard
        isolation, Which means QoS isolation on forwarding plane
        requires better coordination with management plane.

    (3) Independent Management Plane: Like above, network isolation is
        not sufficient, a flexible and more importantly a management
        plane per instance is required to operate on a slice
        independently and autonomously within the constraints of
        resources allocated to the slice.

    (4) Another flexibility requirement is that an operator can deploy
        their new business application or a service in network slice
        with low cost and high speed, and ensure that it does not affect
        existing of business applications adversely.

    (5) Stringent Resource Characteristics: A Network Slicing aware
        infrastructure allows operators to use part of the network
        resources to meet stringent resource characteristics.

    (6) Type of resources: Network Slice instance is a dedicated network



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        that is build and activated on an infrastructure mainly composed
        of, but not limited to, connectivity, storage and computing.

    (7) Programmability: Operator not only can slice a common physical
        infrastructure into different logical networks to meet all kinds
        of new business requirements, but also can use SDN based
        technology to improve the overall network utilization.  By
        providing a flexible programmable interface; the 3rd party can
        develop and deploy new network business rapidly.  Further, if a
        network slicing can run with its own slice controller, this
        network slicing will get more granular control capability [I-
        D.ietf-anima-autonomic-control-plane] to retrieve slice status,
        and issuing slicing flow table, statistics fetch etc.

    (8) Life cycle self-management: It includes creation, operations,
        re- configuration, composition, decomposition, deletion of
        slices.  It would be performed automatically, without human
        intervention and based on a governance configurable model of the
        operators.  As such protocols for slice set-up /operations
        /(de)composition / deletion must also work completely
        automatically.  Self-management (i.e. self- configuration, self-
        composition, self-monitoring, self-optimisation, self-
        elasticity) is carried as part of the slice protocol
        characterization.


    (9) Network slice Self-management: Network slices will need to be
        self-managed by automated, autonomic and autonomous systems in
        order to cope with dynamic requirements, such as flexible
        scalability, extensibility, elasticity, residency and
        reliability of an infrastructure. Network slices will need to be
        self-managed by automated, autonomic and autonomous systems in
        order to cope with dynamic requirements, such as scalability or
        extensibility of an infrastructure. A common information model
        describing uniformly the NS in a single and/or multiple domain
        would support such self-managed.

    (10) Extensibility: Since the Autonomic Slice Networking
        Infrastructure is a relatively new concept, it is likely that
        changes in the way of operation will happen over time.  As such
        new networking functions will be introduced later, which allow
        changes to the way the slices operate.

    (11) Network Slice elasticity: A Network Slice instance has the
        mechanisms and triggers for the growth/shrinkage of all
        resources, and/or network and service functions as enabled by a
        common information model that explicitly provides for elasticity
        policies for scaling up/down resources.



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    (12) Multiple domains activation: Network slice instances are
        concurrently activated as multiple logical, self-contained and
        independent, partitioned network functions and resources on a
        specific infrastructure domain.

    (13) Resource Exposure: Each network slice has the ability to
        dynamically expose and possibly negotiate the parameters that
        characterize an NS as enabled by a common information model that
        explicitly provides monitoring policies for all model
        descriptors.

    (14) Network Tenants: Network slicing support tenants that are
        strongly independent on infrastructure as enabled by a common
        information model that explicitly provides for a level of
        tenants management for the resources dedicated to an instance of
        network slice.

3.  Autonomic Slice Networking

   This section describes the various elements in a network with
   autonomic functions, and how these entities work together, on a high
   level.  Subsequent  sections explain the detailed inside view for
   each of the autonomic network elements, as well as the network
   functions (or interfaces) between those elements.

   One expected autonomic Slice Networking function is the capability
   and resource Usability for a slice. Applications or services
   requiring information of available slice capabilities and resources
   are satisfied by abstracted resource view and control. Usability of
   capabilities and resources can be enabled either by resource
   publishing or by discovery. In the latter case, the service performs
   resource collection directly from the provider of the slice by using
   discovery mechanisms to get total information about the available
   resources to be consumed. In the former, the network provider exposes
   available resources to services (e.g., through a resource catalog)
   reducing the amount of detail of the underlying network.

   Slice Element Manager (SEM) is installed for each control domain.
   Control domain is defined according to geographic location and
   control functions. Each SEM converts requirements from orchestrator
   into virtual resources and manages virtual resources of a slice. SEM
   also exchanges information of virtual resources with other slice
   element managers via a dedicated resource interface. SEM provides
   also capability exposure facilities by allowing 3rd parties to access
   / use via APIs information regarding services provided by the slice
   (e.g. connectivity information, QoS, mobility, autonomicity, etc.)
   and to dynamically customize the network characteristics for
   different diverse use cases (e.g. ultra-low latency, ultra-



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   reliability, value-added services for  enterprises, etc.) within the
   limits set of functions by the operator.

   Physical Element Manager (PEM) is installed for each control domain.
   Control domain is defined according to geographic location and
   control functions. PEM exchanges information of virtual resource with
   SEM via virtual resource interface and interconverts between virtual
   resource and physical resource. The PEM orders physical functions
   (ex. switches) to allocate physical resource via physical resource
   interface.

   Figure 1 shows the high level view of an Autonomic Slice Networking.
   It consists of a number of autonomic nodes resources, which interact
   directly with each other.  Those autonomic nodes resources provide a
   common set of capabilities across a network slice, called the
   "Autonomic Slice Networking Infrastructure" (ASNI).

   The ASN provides functions like naming, addressing, negotiation,
   synchronization, discovery and messaging.

   Autonomic network functions typically span several slices in the
   network.  The atomic entities of an autonomic function are called the
   Autonomic Service Agents" (ASA), which are instantiated on slices.

   In a horizontal view, autonomic functions span across the network, as
   well as the Autonomic Slice Networking Infrastructure.  In a vertical
   view, a slice always implements the ASNI, plus it may have one or
   several Autonomic Service Agents as part of slice capability
   exposure. The Autonomic Networking Infrastructure (ASNI) therefore is
   the foundation for autonomic functions.  The current charter of the
   ANIMA WG includes the specification of the ASNI, using a few
   autonomic functions as use cases.  ASNI would represent a customized
   and an approach [I-D.ietf-anima-reference-model] for implementing a
   general purposed ASI.


        +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
        :            :      Autonomic Slice Function 1   :             :
        : SSA 1      :      SSA 1      :      SSA 1      :      SSA 1  :
        +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
                     :                 :                 :
                     :   +- - - - - - - - - - - - - - +  :
                     :   : Autonomic Slice Function 2 :  :
                     :   :  ASC 2      :      ASC 2   :  :
                     :   +- - - - - - - - - - - - - - +  :
                     :                 :                 :
        +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
        :           Autonomic Slice Networking Infrastructure         :



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        +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
        +                                                             +
        +         +-----------------------------------------+         +
        +         | Autonomic Inter-Slice Orchestration     |         +
        +         +-----------------------------------------+         +
        +          |              |                        |          +
        +----------+       +-----------+                   +----------+
        |Slice 1   |       |Slice 2    |                   | Slice N  |
        |  SEM     |-------|  SEM      |------ ...   ----  |  SEM     |
        |          |       |           |                   |          |
        +----------+       +-----------+                   +----------+
              |                  |                              |
        +-------------------------------------------------------------+
        |                                                             |
        |    PEC1              PEC2                          PECm     |
        |     |  ...           |         ...                  |       |
        |                                                          |
        |          Resources / Network Functions / ANI                |
        |                                                             |
        +-------------------------------------------------------------+
             |            |                  |                    |
        +----------------------+    +------------+       +------------+
        +-------+    +---------+    +  +-------+ +       + +--------+ +
        | Node1.1 --| Node1.N |------ |Node2.x|-...------ | NodeM.y| +
        +-------+    +---------+    +  +-------+ +       + +--------+ +
        +----------------------+    +------------+       +------------+
               Domain 1                Domain 2            Domain M

        Figure 1: High level view of Autonomic Slice Networking

   Additionally, at least 2 autonomous functions are envisioned -
   Autonomous Slice control (ASC) and Slice Service agent (SSA).  These
   are explained in sections below.


4.  Autonomic Inter-Slice Orchestration

   This section describes an autonomic orchestration and its
   functionality.

   Orchestration refers to the system functions that:

      * automated and autonomically  co-ordination of network functions
        in slices

      * autonomically coordinate the slices lifecycle and all the
        components that are part of the slice (i.e.  Service Instances,
        Network Slice Instances, Resources, Capabilities exposure) to



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        ensure an optimized allocation of the necessary resources across
        the network.

      * coordinate a number of interrelated resources, often distributed
        across a number of subordinate domains, and to assure
        transactional integrity as part of the process [TETT1].

      * autonomically control of slice life cycle management, including
        concatenation of slices in each segment of the infrastructure
        including  the data pane, the control plane, and the management
        plane.

      * autonomically coordinate and trigger of slice elasticity and
        placement of logical resources in slices.

      * coordinates and (re)-configure logical resources in the slice by
        taking over the control of all the virtualized network functions
        assigned to the slice.


   It is also the continuing process of allocating resources to satisfy
   contending demands in an optimal manner [TETT2].  The idea of optimal
   would include at least prioritized SLA commitments [SERMODEL], and
   factors such as customer endpoint location, geographic or topological
   proximity, delay, aggregate or fine-grained load, monetary cost,
   fate- sharing or affinity.  The word continuing incorporates
   recognition that the environment and the service demands constantly
   change over the course of time, so that orchestration is a
   continuous, multi-dimensional optimization feedback loop [I-
   D.strassner-anima-control-loops].

   It protects the infrastructure from instabilities and side effects
   due to the presence of many slice components running in parallel.  It
   ensures the proper triggering sequence of slice functionality and
   their stable operation.  It defines conditions/constraints under
   which service components will be activated, taking into account
   operator service and network requirements (inclusive of optimize the
   use of the available network & compute resources and avoid situations
   that can lead to sub-par performance and even unstable and
   oscillatory behaviors.


5. GRASP Resource Reservation / Release Messages flow

   Inter           Slice           Physical
   Slice           Element         Element           Domain      Physical
   Orchestrator    Manager         Manager           Manager     Function




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   |                  |               |                 |               |
   | GRASP Discovery  |GRASP Discovery|GRASP Discovery  |GRASP Discovery|
   |   -Response      |    -Response  |  -Response      | -Response     |
   |  <-------------->| <------------>| <----------->   | <-----------> |
   |                  |               |                 |               |
   | GRASP Request    |               |                 |               |
   |Slicing Objective | GRASP Request |                 |               |
   | ------------->   | Slicing       |                 |               |
   |                  | Objectives    | GRASP Request   |               |
   |                  | ------------> | Slicing         |GRASP Request  |
   |                  |               | Objectives      |Slicing        |
   |                  |               | ----------->    |Objectives     |
   |                  |               |                 |----------->   |
   |                  |               | GRASP           |               |
   |                  |               | Confirm-Waiting |               |
   |                  |               |  <---------     |               |
   |                  |GRASP          |                 |               |
   |                  |Confirm-Waiting|                 |GRASP          |
   |                  | <-----------  |                 |Negotiation    |
   |                  |               |                 |Single/Multiple|
   |                  |               |GRASP Negotiation|Rounds         |
   |                  |               |Single/Multiple  |<----------->  |
   |                  |               |Rounds           |               |
   | GRASP            |               | <----------->   |               |
   | Confirm-Waiting  |               |                 |               |
   |<---------------  |GRASP          |                 |               |
   |                  |Negotiation    |                 |               |
   |                  |Single/Multiple|                 |               |
   |                  |Rounds         |                 |               |
   |GRASP Negotiation | <-----------> |                 |               |
   |Single/Multiple   |               |                 |               |
   |Rounds            |               |                 |               |
   | <------------>   |               |                 |               |
  Figure 2 - GRASP: Network Slice reservation / Release3 Messages Flow

   The above message sequence figure shows the message flows of the
   interactions between Inter-Slice Orchestrator, Slice Element Manager,
   Physical Element Manager, Domain Manager and Physical Network
   functions.

6.  The Autonomic Network Slicing Element


   This section describes an autonomic slice network element and its
   internal architecture.  The reference model explained in the document
   "Autonomic Networking - Definitions and Design Goals" [RFC7575] shows
   the sources of information that an autonomic service agent can
   leverage: Self-management, Self-knowledge, network knowledge (through



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   discovery), Intent [I-D.du-anima-an-intent], and feedback loops.
   Fundamentally, there are two levels inside an autonomic node: the
   level of Autonomic Service Agents, and the level of the Autonomic
   Slice Networking Infrastructure, with the former using the services
   of the latter. The self management functionality (self-configuration,
   self-optimisation, self- healing) could be implemented across the
   Inter Slice Orchestrator, Slice Element Manager and Physical Element
   Manager. Such functionality deals with dynamic

      * coordination the life cycle of slices

      * allocation of resources to slice instances in an efficient way
        that provides required slice instances performance,

      * Service lifecycle, that is typically different than slice
        instance lifecycle should also be managed in the autonomous way.
      * self-configuration, self-optimization and self-healing of
        services of each slice instance. Service lifecycle, that is
        typically different than slice instance lifecycle should also be
        managed in the autonomous way.


   Figure 3 illustrates this concept.

         +------------------------------------------------------------+
         |                                                            |
         | +-----------+        +------------+        +------------+  |
         | | Autonomic |        | Autonomic  |        | Autonomic  |  |
         | | Service   |        | Service    |        | Service    |  |
         | | Agent 1   |        | Agent 2    |        | Agent 3    |  |
         | +-----------+        +------------+        +------------+  |
         |       ^                   ^                     ^          |
         |  - - -| - - API level - - | - - - - - - - - - - |- - - - - |
         |       V                   V                     V         |
         |------------------------------------------------------------|
         | Autonomic Slice Networking Infrastructure                  |
         |    - Service characteristics (ultra-low latency,           |
         |      ultra-reliability, etc)                               |
         |    - Autonomic Control Plane functions                     |
         |    - Autonomic Management Plane functions                  |
         |    - Self-x functions and related control loops elements   |
         |    - Autonomic Slice Addressing                            |
         |      Discovery, negotiation and synchronisation functions  |
         |    - Intent distribution                                   |
         |    - Aggregated reporting and feedback loops               |
         |    - Routing                                               |
         |    - Security mechanisms                                   |
         |------------------------------------------------------------|



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         |             Basic Operating System Functions               |
         +------------------------------------------------------------+
                Figure 3: Model of an autonomic element

   The Autonomic Slice Networking Infrastructure (lower part of Figure
   3) contains slice specific data structures, for example trust
   information about itself and its peers, as well as a generic set of
   functions, independent of a particular usage.  This infrastructure
   should be generic, and support a variety of Autonomic Service Agents
   (upper part of Figure 3).  The Autonomic Control Plane is the summary
   of all interactions of the Autonomic Slice Networking Infrastructure
   with other services.

   The use cases of "Autonomics" such as self-management, self-
   optimisation, etc, are implemented as Autonomic Service Agents.  They
   use the services and data structures of the underlying autonomic
   networking infrastructure.  The Autonomic Slice Networking
   Infrastructure should itself be self-managing.


   The "Basic Operating System Functions" include the "normal OS",
   including the network stack, security functions, etc.  Autonomic
   Network Slicing Element is a composition of autonomic slice service
   agents and autonomic slice control.  Autonomic slice service agents
   obtain specific network resources and provide self-managing and self-
   controlling functions.  An autonomic slice control is a higher-level
   autonomic function that takes the role of life-cycle management of a
   or many slice instances.  There can be many slice control functions
   based on different types or attributes of slice.

7.  The Autonomic Slice Networking Infrastructure

   The Autonomic Networking Infrastructure provides a layer of common
   functionality across an Autonomic Network.  It comprises "must
   implement" functions and services, as well as extensions.  The
   Autonomic Slice Networking Infrastructure (ASNI) resides on top of an
   abstraction layer of resource, network function and network
   infrastructure as shown in figure 1.  The document assumes
   abstraction layer enables different autonomous service agents to
   communicate with the underlying disaggregated and distributed network
   infrastructure, which itself maybe an autonomous networking (AN)
   domain or combination of multiple AN domain.  The goal of ASNI is to
   provide autonomic life-cycle management of network slices.

7.1.  Signaling Between Autonomic Slice Element Managers

   The basic network capabilities are autonomically or through
   traditional techniques are learnt by slice agents.  This depends on



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   the fact that physical infrastructure is an autonomic network or not.
   The GASP extensions signaling   [I-D.liu-anima-grasp-distribution]
   [I-D.liu-anima-grasp-api] [I-D.ietf-anima-grasp] may be used for

      * Discovery of SEMs - a process by which an one SEM discovers
        peers according to a specific discovery objective. The
        discovered SEMs peers may later be used as negotiation
        counterparts or as sources of other coordination activities.

      * Negotiation between SEMs - a process by which two SEMs interact
        to agree on slice logical resource settings that best satisfies
        the objectives of both SEMs.

      * The Synchronization between SEMs - a process by which
        Orchestrator and SEMs interact to receive the current state of
        capability exposure values used at a given time in other SEM.
        This is a special case of negotiation in which information is
        sent but the SEM  or Orchestrator do not request their peers to
        change configuration settings.

      * Self configuration of SEMs - a process by which Orchestrator and
        SEMs interact to receive the current state of capability
        exposure values used at a given time in other SEM. This is a
        special case of synchronization in which information is sent and
        the SEM is requesting their peers to change configuration
        settings.

      * Self optimization of SEMs - a process by which Orchestrator and
        SEMs interact to receive the current state of capability
        exposure values used at a given time in other SEMs. This is a
        special case of configuration in which information is sent and
        the SEM is requesting their peers to change logical resource
        settings in a slice based on an optimisation criteria.

      * Mediation for slice resources - a process by which two SEMs
        interact to agree to logically move resources between slices
        that best satisfy the objectives of both SEMs triggering of
        slice elasticity and placement of logical resources in slices.
        This is a special case of negotiation in  which information is
        sent Orchestrator do request SEMs to change logical resource
        configuration settings.

      * Triggering and governing of elasticity ? a process for autonomic
        scaling intent configuration mechanisms and resources on the
        slice level; it allows rapid provisioning, automatic scaling
        out, or in, of resources. Scale in/out criteria might be used
        for network autonomics in order the controller to react to a
        certain set of variations in monitored slices.



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      * Providing on-demand a self-service network slicing.

   Optionally, SSA capabilities are more interesting to slice control
   autonomic functions for slice creation and install. The slice control
   must have the independent intelligence to process and filter
   capabilities to meet a network slice specification and have low level
   resources allocated for a slice through SSAs.

7.2.  The Autonomic Control Plane

   TBD.

7.3.  Naming & Addressing

   A slice can be instantiated on demand, represents a logical network
   and therefore, must be assigned a unique identifier.  A Slice Service
   Agent (SSA) may support functions of a single or multiple slices and
   communicate with each other, using the addressing of the Autonomic or
   traditional (non-autonomic) Networking Infrastructure reside on.  An
   SSA complies with ACP addressing mechanisms and in a domain, i.e., As
   part of the enrolment process the registrar assigns a number to the
   device, which is unique for slicing registrar and in ASNI domain.

7.4.  Discovery

   Slices themselves are not discovered but are instantiated through
   slice control autonomic function.  However, both slice service agents
   and slice control functions must be discovered.  Even though
   autonomic control plane will support discovery of all the SSAs and
   slice control, it may not be necessary.

7.5.  Routing

   Autonomic network slicing follows single routing protocol as
   described in [I-D.ietf-anima-autonomic-control-plane].


8.  Security and Trust Infrastructure

   An Autonomic Slice Network is self-protecting.  All protocols are
   secure by default, without the requirement for the administrator to
   explicitly configure security.

   TBD.

8.1.  Public Key Infrastructure

   An autonomic domain uses a PKI model.  The root of trust is a



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   certification authority (CA).  A registrar acts as a registration
   authority (RA).

   A minimum implementation of an autonomic domain contains one CA, one
   Registrar, and network elements.

8.2.  Domain Certificate

   TBD.

9.  Cross-Domain Functionality

   TBD.

10.  Autonomic Service Agents (ASA)

   This section describes how autonomic services run on top of the
   Autonomic Slice Networking Infrastructure.  There are at least two
   different types of autonomic functions are known:

     1. Slice Service Agents are low level functions that learn
        capabilities of underlying infrastructure in terms of interfaces
        and available resources.  They coordinate with Slice control to
        associate these resources with specific slice instances in
        effect performing full life cycle management of these resources.
     2. Slice Control Autonomic Function: Slice control is responsible
        for high-level life-cycle management of a slice itself.  This
        function will hold slice instances and their attributes related
        data structures in autonomic network slice infrastructure.  As
        an example, a slice is defined for high bandwidth, highly secure
        transactional application.  A slice control must be capable of
        negotiating resources required across different SSAs.


   Out of scope are details of the mechanisms how the information is
   represented and exchanged between the two autonomic functions.

11.  Management and Programmability

   This section describes how an Autonomic Network is managed, and
   programmed.

11.1.  How a Slice Network Is Managed

   Slice autonomic  management is driven by Slice Element Managers,
   there are five categories operation:

     1. Creating a network slice: Receive a network slice resource



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        description request, upon successful negotiation with SSA
        allocate resource for it.
     2. Shrink/Expand slice network: Dynamically alter resource
        requirements for a running slice network according service load.
     3. (Re-)Configure slice network: The slice management user deploys
        a user level service into the slice.  The slice control takes
        over the control of all the virtualized network functions and
        network programmability functions assigned to the slice, and
        (re-)configure them  as appropriate to provide the end-to-end
        service.
     5. Self-X slice operation: namely self-configuration, self-
        composition, self-monitoring, self-optimisation, self-elasticity
        would be carried out as part of new slice protocols.

11.2.  Intent

   TBD.

11.3.  Control Loops

   TBD.

11.4.  APIs

   The API model of for autonomic slicing semantically, is grouped into
   the following APIs to be defined.

11.4.1.  Slice Control APIs

     1. Create a slice network on user request.  The request includes
        resource description.  A unique identify a slice network, group
        all the resource.
     2. Destroy a slice network identified by it's uuid.
     3. Query a slice network slicing state by its uuid.
     4. Modify a slice network.

11.4.2.  Service Agent - Device APIs

   A service agent will interface with the physical infrastructure
   either through an autonomic network or traditional infrastructure.
   Depending upon which a device can either have autonomic or non-
   autonomic addressing.  Service agents are required to perform life
   cycle management of network elements participating in a network slice
   and the following APIs are needed for addition, removal or update of
   a specific device.  A device may be a logical or physical network
   element.  Optionally, it may be a network function.

11.4.3.  Service Agent - Port APIs



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   A port may be a physical or logical network port in a slice depending
   upon whether underlying infrastructure is an autonomic or traditional
   network.  Service agents must be able to control the operational
   state of these ports.  APIs are needed for addition, removal, update
   and operational state retrieval of a specific port.

11.4.4.  Service Agent - Link APIs

   A link connects two or more ports of devices described in above
   section.  Service agents must be able to control the operational and
   connection status of these links through APIs for addition, removal,
   update and state retrieval for each link.

11.5.  Relationship with MANO

   Please refer to [MANO] for MANO introduction.

12.  Security Considerations

12.1.  Threat Analysis

   TBD.

12.2.  Security Mechanisms

   TBD.

13.  IANA Considerations

   This document requests no action by IANA.

14.  Acknowledgements

   This document was produced using the xml2rfc tool [RFC2629].

14.  References

14.1.  Normative References

   [I-D.ietf-anima-grasp] Bormann, C., Carpenter, B., and B. Liu, "A
              Generic Autonomic Signaling Protocol (GRASP)", draft-ietf-
              anima- grasp-10 (work in progress), March 2017.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, DOI
              10.17487/RFC2119, March 1997, <http://www.rfc-
              editor.org/info/rfc2119>.




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   [RFC7665]       Halpern, J., Pignataro, C., "Service Function Chaining
              (SFC) Architecture", October 2015
              <https://tools.ietf.org/html/rfc7665>.

   [RFC2629]  Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629, DOI
              10.17487/RFC2629, June 1999, <http://www.rfc-
              editor.org/info/rfc2629>.

14.2.  Informative References

   [ChinaCom09] "A. Galis et all - "Management and Service-aware
              Networking Architectures (MANA) for Future Internet" -
              Invited paper IEEE 2009 Fourth International Conference on
              Communications and Networking in China (ChinaCom09) 26-28
              August 2009, Xi'an, China,
              <http://www.chinacom.org/2009/index.html>.".

   [GENI]     "GENI Key Concepts" - Global Environment for Network
              Innovations (GENI)
              <http://groups.geni.net/geni/wiki/GENIConcepts>.".

   [I-D.du-anima-an-intent] Du, Z., Jiang, S., Nobre, J., Ciavaglia, L.,
              and M. Behringer, "ANIMA Intent Policy and Format", draft-
              du- anima-an-intent-04 (work in progress), July 2016.

   [I-D.ietf-anima-autonomic-control-plane] Behringer, M., Eckert, T.,
              and S. Bjarnason, "An Autonomic Control Plane", draft-
              ietf-anima-autonomic-control- plane-03 (work in progress),
              July 2016.

   [I-D.ietf-anima-reference-model] Behringer, M., Carpenter, B.,
              Eckert, T., Ciavaglia, L., Pierre, P., Liu, B., Nobre, J.,
              and J. Strassner, "A Reference Model for Autonomic
              Networking", draft-ietf- anima-reference-model-02 (work in
              progress), July 2016.

   [I-D.liu-anima-grasp-api] Carpenter, B., Liu, B., Wang, W., and X.
              Gong, "Generic Autonomic Signaling Protocol Application
              Program Interface (GRASP API)", draft-liu-anima-grasp-api-
              02 (work in progress), September 2016.

   [I-D.liu-anima-grasp-distribution] Liu, B. and S. Jiang, "Information
              Distribution over GRASP", draft-liu-anima-grasp-
              distribution-02 (work in progress), September 2016.

   [I-D.strassner-anima-control-loops] Strassner, J., Halpern, J., and
              M. Behringer, "The Use of Control Loops in Autonomic
              Networking", draft-strassner- anima-control-loops-01 (work



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              in progress), April 2016.

   [IMT2020]  "ITU-T IMT2020 document "Report on Gap Analysis" - ITU-T
              IMT2020 ITU- Dec 2015 Published by ITU-T IMT2020.
              <http://www.itu.int/en/ITU-T/focusgroups/imt-2020/Pages/
              default.aspx>.".

   [MANO]     "ETSI European Telecommunications Standards Institute.
              Network Functions Virtualisation (NFV); Management and
              Orchestration v1.1.1.  Website, December 2014.
              <http://www.etsi.org/deliver/etsi_gs/NFV-
              MAN/001_099/001/01.01.01_60/gs_ nfv-man001v010101p.pdf>.".

   [NGMN]     "Hedmar,P., Mschner, K., et all - NGMN Alliance document
              "Description of Network Slicing Concept", January 2016.
              <https://www.ngmn.org/uploads/
              media/160113_Network_Slicing_v1_0.pdf>.".

   [NGS-3GPP] "Study on Architecture for Next Generation System" -
              latest version v1.0.2 September 2016
              <http://www.3gpp.org/ftp/tsg_sa/WG2_Arch/Latest_SA2_Specs/
              Latest_draft_S2_Specs>.".

   [ONF]      "Paul, M, Schallen, S., Betts, M., Hood, D., Shirazipor,
              M., Lopes, D., Kaippallimalit, J., - Open Network
              Fundation document "Applying SDN Architecture to 5G
              Slicing", April 2016.
              <https://www.opennetworking.org/images/stories/downloads/
              sdn-resources/technical-reports/
              Applying_SDN_Architecture_to_5G_Slicing_TR-526.pdf>.".

   [NS1]     "L. Geng, J. Dong, S. Bryant, K., Makhijani, A., Galis, X.
              de Foy, S. Kuklinski, - Network Slicing Architecture, July
              2017. <https://tools.ietf.org/html/draft-geng-netslices-
              architecture-02>.".

   [NS2]     "L. Geng, L. Wang,  S. Kuklinski, L. Qiang, S. Matsushima,
              A., Galis, L. Contreras - Problem Statement of Supervised
              Heterogeneous Network Slicing - October 2017
              <https://datatracker.ietf.org/doc/draft-geng-coms-problem-
              statement/>.".

   [ASN]     "A., Galis, K., Makhijani, D. Yu, B. Liu - Autonomic Slice
              Networking-Requirements and Reference Model - May 2017 <
              https://datatracker.ietf.org/doc/draft-galis-anima-
              autonomic-slice-networking/>.".

   [RFC7575]  Behringer, M., Pritikin, M., Bjarnason, S., Clemm, A.,



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              Carpenter, B., Jiang, S., and L. Ciavaglia, "Autonomic
              Networking: Definitions and Design Goals", RFC 7575, DOI
              10.17487/RFC7575, June 2015, <http://www.rfc-
              editor.org/info/rfc7575>.

   [RFC7576]  Jiang, S., Carpenter, B., and M. Behringer, "General Gap
              Analysis for Autonomic Networking", RFC 7576, DOI
              10.17487/RFC7576, July 2016, <http://www.rfc-
              editor.org/info/rfc7576>.

   [TETT1]    Guerzoni, R., Vaishnavi, I., Pares-Caparros, D., Galis,
              A., et all "Analysis of End-to-End Multi Domain Management
              and Orchestration Frameworks for Software Defined
              Infrastructures: an Architectural Survey", Transactions on
              Emerging Telecommunications Technologies, Wiley Online
              Library,  DOI: 10.1002/ett.3103, June 2016,
              <onlinelibrary.wiley.com/doi/10.1002/ett.3103/pdf>.

   [TETT2]    Karl, H., Draxler, S., Peuster, M, Galis, A., et all
              "DevOps for Network Function Virtualization: An
              Architectural Approach", Transactions on Emerging
              Telecommunications Technologies Wiley Online Library, DOI:
              10.1002/ett.3084, July 2016,
              <http://onlinelibrary.wiley.com/doi/10.1002/ett.3084/full>.

   [SERMODEL]  C., Borman, B. Carpenter, B., Liu, "Service Models
              Explained draft-wu-opsawg-service-model-explained-05
              <https://datatracker.ietf.org/doc/draft-wu-opsawg-service-
              model- explained/>.

   [5GNS]    Galis, A. (UCL), Chih-Lin I (China Mobile) - "Towards 5G
              Network Slicing - Motivations and Challenges"  March 2017,
              < IEEE 5G Tech Focus, Volume 1, Number 1, March 2017-
              http://5g.ieee.org/tech-focus/march-2017#networkslicing>.

Authors' Addresses


                 Alex Galis (editor)
                 University College London
                 Department of Electronic and Electrical Engineering
                 Torrington Place
                 London  WC1E 7JE
                 United Kingdom

                 Email: a.galis@ucl.ac.uk

                 Kiran Makhijani



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                 Huawei Technologies
                 2890, Central Expressway
                 Santa Clara  CA 95032
                 USA

                 Email: USA Email: kiran.makhijani@huawei.com

                 Delei Yu
                 Huawei Technologies
                 Q22, Huawei Campus
                 No.156 Beiqing Road
                 Hai-Dian District, Beijing 100095
                 P.R. China

                 Email: yudelei@huawei.com

                 Bing Liu
                 Huawei Technologies Co., Ltd
                 Q14, Huawei Campus
                 No.156 Beiqing Road
                 Hai-Dian District, Beijing 100095
                 P.R. China

                 Email: leo.liubing@huawei.com



























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