Autonomic Slice
Networking–Requirements and Reference ModelUniversity College LondonDepartment of Electronic and Electrical EngineeringTorrington PlaceLondonWC1E 7JEUnited Kingdoma.galis@ucl.ac.ukHuawei Technologies2890, Central ExpresswaySanta ClaraCA 95032USAUSA Email: kiran.makhijani@huawei.comHuawei TechnologiesQ22, Huawei CampusNo.156 Beiqing RoadHai-Dian District, Beijing100095P.R. Chinayudelei@huawei.comThis document describes the technical requirements and the related
reference model for the intercommunication and coordination among
devices in Slicing 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.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 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. 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.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.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.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. 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) exposure of abstract resources towards service and
management clients that are needed for the operation of slicesThe 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 which 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.Slice creation: management plane create virtual or physical network
functions and connects them as appropriate and instantiate them in the
slice.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 which 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.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.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.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.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 to retrieve slice status, and issuing slicing flow
table, statistics fetch etc.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.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.Transport network shall provide QoS isolation, flexible network
operation and management, and improve network utilization among
different business.The flexibility behind the slice concept needs to address QoS
guarantee on the transport network and enable network openness.Other considerations and requirements: TBD.A number of slice definitions were used in the last 10 years in
distributed and federated testbed research ,
future internet research and more recently
in the context of 5G research , , , .A unified Slice definition usable in the context of Autonomic
Networking consist of 4 components:Service Instance component,Network Slice Instance component,Resources component andSlice Capability exposure componentThe Service Instance component represents the end-user service or
business services which are to be supported. It is an instance of an
end-user service or a business service that is realized within or by a
Network Slice. Each service is represented by a Service Instance.
Services and service instances would be provided by the network
operator or by 3rd parties.A Network Slice Instance component is represented by a set of
network 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 which are required by a Service
Instance. A Network Slice Instance may also be shared across multiple
Service Instances provided by the network operator. The Network Slice
Instance may be composed by none, one or more Sub-network Instances,
which may be shared by another Network Slice Instance.Slice Capability exposure component is 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-reliability, value-added services for enterprises, etc.) within
the limits set of functions by the operator. It includes a description
of the structure (and contained components) and configuration of the
slice instance.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 - It refers to processing functions in a network.
This includes but is not limited to telecom nodes functionality, as
well as switching functions e.g. switching function, IP routing
functions.Virtual Network Function - One or more virtual machines running
different software and processes on top of high-volume servers,
switches and storage, or cloud computing infrastructure, and capable
of implementing network functions traditionally implemented via custom
hardware appliances and middleboxes (e.g. router, NAT, firewall, load
balancer, etc.).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.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 ASNI 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 for
implementing a general purposed ASI.Additionally, at least 2 autonomous functions are envisioned -
Autonomous Slice control (ASC) and Slice Service agent (SSA). These are
explained in sections below.This section describes an autonomic orchestration and its
functionality. Orchestration refers to the functions that 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 ensure an optimized allocation of the
necessary resources across the network. It is expected to coordinate a
number of interrelated resources, often distributed across a number of
subordinate domains, and to assure transactional integrity as part of
the process. It is also the continuing process of allocating resources to satisfy
contending demands in an optimal manner. The idea of optimal would
include at least prioritized SLA commitments, 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. 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.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-knowledge, network knowledge (through discovery), 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.Figure 2 illustrates this concept. The Autonomic Slice Networking Infrastructure (lower part of
Figure 2) 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 2). 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.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.The basic network capabilities are autonomically or through
traditional techniques are learnt by slice agents. This depends on the
fact that physical infrastructure is an autonomic network or not. The
GASP signaling may be used to expose capabilities among SSAs or slice
control. 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. 6.2 The Autonomic
Control Plane.TBD.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.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.Autonomic network slicing follows single routing protocol as
described in .TBD.An Autonomic Slice Network is self-protecting. All protocols are
secure by default, without the requirement for the administrator to
explicitly configure security.TBD.An autonomic domain uses a PKI model. The root of trust is a
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.TBD.TBD.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: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.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.This section describes how an Autonomic Network is managed, and
programmed.Slice network management is driven by Slice control, there are four
categories operation:Creating a network slice: Receive a network slice resource
description request, upon successful negotiation with SSA allocate
resource for it.Shrink/Expand slice network: Dynamically alter resource
requirements for a running slice network according service load.
(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.Destroy slice network: Recycle all resource from the
infrastructure.TBD.TBD.The API model of for autonomic slicing semantically, is grouped
into the following APIs to be defined.Create a slice network on user request. The request includes
resource description. A unique identify a slice network, group
all the resource. Destroy a slice network identified by it's id. Query a slice network slicing state by it's uuid. Modify a slice network.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.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.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.Please refer to for MANO introduction. TBD.TBD.TBD.This document requests no action by IANA.Thanks Bing Liu for helping editing the draft.This document was produced using the xml2rfc tool .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>.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>.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>."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>."GENI Key Concepts" - Global Environment for Network
Innovations (GENI)
<http://groups.geni.net/geni/wiki/GENIConcepts>.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>.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>.