Applicability of Abstraction and Control of Traffic Engineered Networks (ACTN) to IETF Network Slicing
draft-ietf-teas-applicability-actn-slicing-10
| Document | Type | Active Internet-Draft (teas WG) | |
|---|---|---|---|
| Authors | Daniel King , John Drake , Haomian Zheng , Adrian Farrel | ||
| Last updated | 2024-08-29 (Latest revision 2024-08-28) | ||
| Replaces | draft-king-teas-applicability-actn-slicing | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Informational | ||
| Formats | |||
| Reviews |
GENART IETF Last Call review
(of
-07)
by Peter Yee
Ready w/nits
|
||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Vishnu Pavan Beeram | ||
| Shepherd write-up | Show Last changed 2024-06-09 | ||
| IESG | IESG state | RFC Ed Queue | |
| Action Holders |
(None)
|
||
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | Jim Guichard | ||
| Send notices to | vbeeram@juniper.net | ||
| IANA | IANA review state | IANA OK - No Actions Needed | |
| IANA action state | No IANA Actions | ||
| RFC Editor | RFC Editor state | MISSREF | |
| Details |
draft-ietf-teas-applicability-actn-slicing-10
TEAS Working Group D. King
Internet-Draft Old Dog Consulting
Intended status: Informational J. Drake
Expires: 1 March 2025 Independent
H. Zheng
Huawei Technologies
A. Farrel
Old Dog Consulting
28 August 2024
Applicability of Abstraction and Control of Traffic Engineered Networks
(ACTN) to IETF Network Slicing
draft-ietf-teas-applicability-actn-slicing-10
Abstract
Network abstraction is a technique that can be applied to a network
domain to obtain a view of potential connectivity across the network
by utilizing a set of policies to select network resources.
Network slicing is an approach to network operations that builds on
the concept of network abstraction to provide programmability,
flexibility, and modularity. It may use techniques such as Software
Defined Networking (SDN) and Network Function Virtualization (NFV) to
create multiple logical or virtual networks, each tailored for a set
of services that share the same set of requirements.
Abstraction and Control of Traffic Engineered Networks (ACTN) is
described in RFC 8453. It defines an SDN-based architecture that
relies on the concept of network and service abstraction to detach
network and service control from the underlying data plane.
This document outlines the applicability of ACTN to network slicing
in a Traffic Engineered (TE) network that utilizes IETF technologies.
It also identifies the features of network slicing not currently
within the scope of ACTN and indicates where ACTN might be extended.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
King, et al. Expires 1 March 2025 [Page 1]
Internet-Draft ACTN and Network Slicing August 2024
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 1 March 2025.
Copyright Notice
Copyright (c) 2024 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 (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Overview of Key Requirements for Network Slicing . . . . . . 5
2.1. Resource Partitioning . . . . . . . . . . . . . . . . . . 5
2.2. Network Topology Customization and Virtualization . . . . 6
2.3. Service Isolation . . . . . . . . . . . . . . . . . . . . 6
2.4. Orchestration . . . . . . . . . . . . . . . . . . . . . . 7
3. Abstraction and Control of Traffic Engineered (TE) Networks
(ACTN): Overview of Key Components . . . . . . . . . . . 7
3.1. ACTN Virtual Network as a Network Slice . . . . . . . . . 8
3.2. ACTN Virtual Network and Scaling Network Slices . . . . . 9
3.3. Management Components for ACTN and Network Slicing . . . 9
3.4. Examples of ACTN Delivering Network Slice Services . . . 11
3.4.1. ACTN Used for Virtual Private Line . . . . . . . . . 11
3.4.2. ACTN Used for VPN Delivery Model . . . . . . . . . . 13
3.4.3. ACTN Used to Deliver a Virtual Customer Network . . . 15
4. YANG Models . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.1. Network Slice Service Mapping from TE to ACTN VN
Models . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.2. Interfaces and YANG Models . . . . . . . . . . . . . . . 18
4.3. ACTN VN Telemetry . . . . . . . . . . . . . . . . . . . . 19
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
6. Security Considerations . . . . . . . . . . . . . . . . . . . 20
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 21
King, et al. Expires 1 March 2025 [Page 2]
Internet-Draft ACTN and Network Slicing August 2024
9. Normative References . . . . . . . . . . . . . . . . . . . . 21
10. Informative References . . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
1. Introduction
The principles of network resource separation are not new. For
years, the concepts of separated overlay and logical (virtual)
networking have existed, allowing multiple services to be deployed
over a single physical network comprised of a single or multiple
layers. However, several key aspects differentiate overlay and
virtual networking from network slicing.
A network slice is a virtual (that is, logical) network with its own
network topology and a set of network resources that are used to
provide connectivity that conforms to specific Service Level
Agreements (SLAs) or a set of Service Level Objectives (SLOs). The
network resources used to realize a network slice belong to the
network that is sliced. The resources may be assigned and dedicated
to an individual slice, or they may be shared with other slices
enabling different degrees of service guarantee and providing
different levels of isolation between the traffic in each slice.
[RFC9543] provides a definition for network slicing in the context of
IETF network technologies. In particular, that document defines the
term "IETF Network Slice" as the generic network slice concept
applied to a network that uses IETF technologies. An IETF Network
Slice could span multiple technologies (such as IP, MPLS, or optical)
and multiple administrative domains. The logical network that is an
IETF Network Slice may be kept separate from other concurrent logical
networks with independent control and management: each can be created
or modified on demand. Since this document is focused entirely on
IETF technologies, it uses the term "network slice" as a more concise
expression. Further discussion on the topic of IETF Network Slices
and details of how an IETF Network Slice service may be requested and
realized as an IETF Network Slice can be found in [RFC9543].
Within this document, the terms "network slice", "network slice
service", and "network slice controller" refer to network slicing of
networks built using IETF technologies as described in [RFC9543].
At one end of the spectrum, a Virtual Private Wire (VPW) or a Virtual
Private Network (VPN) may be used to build a network slice. In these
cases, the network slices do not require the service provider to
isolate network resources for the provision of the service - the
service is "virtual".
King, et al. Expires 1 March 2025 [Page 3]
Internet-Draft ACTN and Network Slicing August 2024
At the other end of the spectrum, there may be a detailed description
of a complex network service that will meet the needs of a set of
applications with connectivity and service function requirements that
may include compute resources, storage capabilities, and access to
content. Such a service may be requested dynamically (that is,
instantiated when an application needs it, and released when the
application no longer needs it), and modified as the needs of the
application change. An example of such a type of service can be
provided using an enhanced VPN described in
[I-D.ietf-teas-enhanced-vpn]. It is often based on Traffic
Engineering (TE) constructs in the underlay network.
Abstraction and Control of TE Networks (ACTN) [RFC8453] is a
framework that facilitates the abstraction of underlying network
resources to higher-layer applications and that allows network
operators to create and supply virtual networks for their customers
through the abstraction of the operators' network resources.
ACTN is a toolset capable of delivering network slice functionality.
This document outlines the application of ACTN and associated
enabling technologies to provide network slicing in a network that
utilizes IETF TE-based technologies. It describes how the ACTN
functional components can be used to support model-driven
partitioning of resources into variable-sized bandwidth units to
facilitate network sharing and virtualization. Furthermore, the use
of model-based interfaces to dynamically request the instantiation of
virtual networks can be extended to encompass requesting and
instantiation of specific service functions (which may be both
physical or virtual), and to partition network resources such as
compute resources, storage capability, and access to content. In
Section 3, the document highlights how the ACTN approach might be
extended to address the requirements of network slicing where the
underlying network is TE-capable.
1.1. Terminology
This document re-uses terminology from [RFC8453], [RFC9543] and
[I-D.ietf-teas-enhanced-vpn].
Service Provider: See "Provider" in [RFC9543].
Consumer: See [RFC9543].
Service Functions (SFs): Components that provide specific functions
within a network. SFs are often combined in a specific sequence
called a service function chain to deliver services [RFC7665].
Resource: Any feature, including connectivity, buffers, compute,
King, et al. Expires 1 March 2025 [Page 4]
Internet-Draft ACTN and Network Slicing August 2024
storage, and content delivery that forms part of or can be
accessed through a network. Resources may be shared between
users, applications, and clients, or they may be dedicated for use
by a unique customer.
Infrastructure Resources: The hardware and software for hosting and
connecting SFs. These resources may include computing hardware,
storage capacity, network resources (e.g., links and switching/
routing devices enabling network connectivity), and physical
assets for radio access.
Service Level Agreement (SLA): See [RFC9543].
Service Level Expectation (SLE): See [RFC9543].
Service Level Objective (SLO): See [RFC9543].
IETF Network Slice Service: See [RFC9543].
2. Overview of Key Requirements for Network Slicing
According to Section 6.2 of [RFC9543] "Expressing Connectivity
Intents", the customer expresses requirements for a particular
network slice by specifying what is required rather than how the
requirement is to be fulfilled. That is, the customer's view of a
network slice is an abstract one expressed as a network slice service
request.
The concept of network slicing is a key capability to serve a
customer with a wide variety of different service needs expressed as
SLOs/SLEs in terms of, e.g., latency, reliability, capacity, and
service function-specific capabilities.
This section outlines the key capabilities required to realize
network slicing in a TE-enabled IETF technology network.
2.1. Resource Partitioning
Network resources can be allocated and dedicated for use by a
specific network slice service, or they may be shared among multiple
slice services. This allows a flexible approach that can deliver a
range of services by partitioning (that is, slicing) the available
network resources to make them available to meet the customer's SLA.
King, et al. Expires 1 March 2025 [Page 5]
Internet-Draft ACTN and Network Slicing August 2024
2.2. Network Topology Customization and Virtualization
Network virtualization enables the creation of multiple virtual
networks that are operationally decoupled from the underlying
physical network and are run on top of it. Slicing enables the
creation of virtual networks as customer services.
2.3. Service Isolation
A customer may request, through their SLA, that changes to the other
services delivered by the service provider do not have any negative
impact on the delivery of the service. This quality is referred to
as "isolation" in (Section 8 of [RFC9543]).
Delivery of service isolation may be achieved in the underlying
network by various forms of resource partitioning ranging from
dedicated allocation of resources for a specific slice, to sharing of
resources with safeguards.
Although multiple network slices may utilize resources from a single
underlying network, isolation should be understood in terms of the
following three categorizations.
* Performance isolation requires that service delivery for one
network slice does not adversely impact congestion, packet drop,
or performance levels perceived by the users of other slices.
* Security isolation means that attacks or faults occurring in one
slice do not impact on other slices. Moreover, the security
functions supporting each slice must operate independently so that
an attack or misconfiguration of security in one slice will not
prevent proper security function in the other slices. Further,
privacy concerns require that traffic from one slice is not
delivered to an endpoint in another slice, and that it should not
be possible to determine the nature or characteristics of a slice
from any external point.
* Management isolation means that each slice must be independently
viewed, utilized, and managed as a separate network. Furthermore,
it should be possible to prevent the operator of one slice from
being able to control, view, or detect any aspect of any other
network slice.
King, et al. Expires 1 March 2025 [Page 6]
Internet-Draft ACTN and Network Slicing August 2024
2.4. Orchestration
An orchestrator is used to coordinate disparate processes and
resources for creating, managing, and deploying the network slicing
service in a network. The following aspects of orchestration should
be considered:
* Multi-domain Orchestration: Managing connectivity to set up a
network slice across multiple administrative domains.
* End-to-end Orchestration: Combining resources for an end-to-end
service (e.g., underlay connectivity with firewalling, and
guaranteed bandwidth with minimum delay).
3. Abstraction and Control of Traffic Engineered (TE) Networks (ACTN):
Overview of Key Components
ACTN is designed to facilitate end-to-end connectivity and provides
virtual connectivity services (such as virtual links and virtual
networks) to the user. The ACTN framework [RFC8453] introduces three
functional components and two interfaces:
* Customer Network Controller (CNC)
* Multi-domain Service Coordinator (MDSC)
* Provisioning Network Controller (PNC)
* CNC-MDSC Interface (CMI)
* MDSC-PNC Interface (MPI)
RFC 8453 also highlights how:
* Abstraction of the underlying network resources is provided to
higher-layer applications and customers.
* Virtualization is achieved by selecting resources according to
criteria derived from the details and requirements of the
customer, application, or service.
* Creation of a virtualized environment is performed to allow
operators to view and control multi-domain networks as a single
virtualized network.
* A network is presented to a customer as a single virtual network
via open and programmable interfaces.
King, et al. Expires 1 March 2025 [Page 7]
Internet-Draft ACTN and Network Slicing August 2024
The ACTN infrastructure resources include traffic-engineered network
capabilities. The concept of traffic engineering is broad: it
describes the planning and operation of networks using a method of
reserving and partitioning of network resources in order to
facilitate traffic delivery across a network (see [RFC9522] for more
details).
In the context of ACTN, traffic engineered infrastructure resources
may include Statistical Packet Bandwidth, which refers to using
statistical methods instead of assigning fixed bandwidth. This
approach allocates bandwidth based on how data is flowing and
statistical multiplexing. ACTN traffic engineered network resources
also consider the physical parts of the network, such as optical
channels and time slots, which facilitates the best use of the
network's resources by matching bandwidth with real-time traffic
demands.
Therefore, an ACTN network may be "sliced", with each customer being
given a different partial and abstracted topology view of the
physical underlay network.
3.1. ACTN Virtual Network as a Network Slice
To support multiple customers, each with its own view and control of
a virtual network constructed using an underlay network, a service
provider needs to partition the network resources to create network
slices assigned to each customer.
An ACTN Virtual Network (VN) is a customer view of a slice of the
ACTN infrastructure resources. It is a network slice that is
presented to the customer by the ACTN provider as a set of abstracted
resources. See [I-D.ietf-teas-actn-vn-yang] for a detailed
description of ACTN VNs and an overview of how various different
types of YANG models are applicable to the ACTN framework.
Depending on the agreement between a customer and a provider, various
VN operations are possible:
* Network Slice Creation: A VN could be pre-configured and created
through static configuration or through a dynamic request and
negotiation between a customer and service provider. The VN must
meet the network slice requirements specified in the SLA to
satisfy the customers objectives.
King, et al. Expires 1 March 2025 [Page 8]
Internet-Draft ACTN and Network Slicing August 2024
* Network Slice Operations: The VN may be modified or deleted based
on direct customer requests. Also, the way that the VN is
engineered can be adjusted by the operator to continuously ensure
that the delivered service complies with the requested SLA. The
customer can further act upon the VN to manage their traffic flows
across the network slice.
* Network Slice View: A VN topology is viewed from the customer's
perspective. This may be the entire VN topology, or a collection
of tunnels that are expressed as customer endpoints, access links,
intra-domain paths and inter-domain links.
Section 3, "Virtual Network Primitives", in [RFC8454] describes a set
of functional primitives that support these different ACTN VN
operations.
3.2. ACTN Virtual Network and Scaling Network Slices
If the service provider must manage and maintain state in the core of
the network for every network slice, then this will quickly limit the
number of customer services that can be supported.
The importance of scalability for network slices is discussed in
[I-D.ietf-teas-enhanced-vpn] and further in
[I-D.ietf-teas-nrp-scalability]. That work notes the importance of
collecting network slices or their composite connectivity constructs
into groups that require similar treatment in the network before
realizing those groups in the network.
The same consideration applies to ACTN VNs. But fortunately, ACTN
VNs may be arranged hierarchically by recursing the MDSCs so that one
VN is realized over another VN. This allows the VNs presented to the
customer to be aggregated before they are instantiated in the
physical network.
3.3. Management Components for ACTN and Network Slicing
The ACTN management components (CNC, MDSC, and PNC) and interfaces
(CMI and MPI) are introduced in Section 3 and described in detail in
[RFC8453]. The management components for network slicing are
described in [RFC9543] and are known as the customer orchestration
system, the IETF Network Slice Controller (NSC), and the network
controller. The network slicing management components are separated
by the Network Slice Service Interface and the Network Configuration
Interface, modeling the architecture described in [RFC8309].
King, et al. Expires 1 March 2025 [Page 9]
Internet-Draft ACTN and Network Slicing August 2024
The mapping between network slicing management components and ACTN
management components is presented visually in Figure 1 and provides
a reference for understanding the material in Section 3.4 and
Section 4.
+-------------------------------------+ | +---------------+
| | | | Service |
| Consumer orchestration system | =====> | Orchestrator |
| | | | (1) |
+-------------------------------------+ | +---------------+
^ | ^
IETF Network Slice | | | XMI (2)
Service Interface | | |
v | v
+-------------------------------------+ | +---------------+
| | | | MDSC |
| IETF Network Slice Controller (NSC) | =====> | (Network |
| | | | Orchestrator) |
+-------------------------------------+ | +---------------+
^ | ^
Network | | |
Configuration | | | MPI
Interface | | |
v | v
+-------------------------------------+ | +---------------+
| Network Controllers | =====> | PNC/MSDCs |
+-------------------------------------+ | +---------------+
Figure 1: Mapping Between IETF Network Slice and ACTN Management
Components
Note 1 - The Service Orchestrator may also contain some MDSC service-
related functions, as described in section 4.2 of [RFC8453].
Note 2 - The Service Orchestrator-to-MDSC Interface (XMI) is an
interface between two MDSC functional elements encompassing different
MDSC service-related functions which is not defined in [RFC8453].
Note 2 - The Service Orchestrator-to-MDSC Interface (XMI) is an
interface between two MDSC functional elements encompassing different
MDSC service-related functions which is not defined in [RFC8453].
Depending on the function being delivered, the XMI might be realised
by the Layer 2 VPN Network Management YANG model [RFC9291] or the
Layer 3 VPN Network Management YANG model [RFC9182].
King, et al. Expires 1 March 2025 [Page 10]
Internet-Draft ACTN and Network Slicing August 2024
3.4. Examples of ACTN Delivering Network Slice Services
The following examples build on the ACTN framework to provide
control, management, and orchestration for the network slice life-
cycle. These network slices utilize common physical infrastructure,
and meet specific service-level requirements.
Three examples are shown. Each uses ACTN to achieve a different
network slicing scenario. All three scenarios can be scaled up in
capacity or be subject to topology changes as well as changes in
customer requirements.
3.4.1. ACTN Used for Virtual Private Line
In the example shown in Figure 2, ACTN provides virtual connections
between multiple customer locations (sites accessed through Customer
Edge nodes - CEs). The service is requested by the customer (via
CNC-A) and delivered as a Virtual Private Line (VPL) service. The
characteristics of this model include the following benefits.
* Programmable: The service setup and operation are managed by the
network provider via APIs.
* Virtual: The private line connectivity is provided from Site A to
Site C (VPL1) and from Site B to Site C (VPL2) across the ACTN
infrastructure resources (physical network).
* Flexible: On-demand adjustments to the connectivity and bandwidth
are available according to the customer's requests, which may be
automated.
In terms of the network slicing concept defined in [RFC9543], in this
example the customer requests a single network slice with two pairs
of point-to-point connectivity constructs between the service
demarcation points CE1 and CE3, and CE2 and CE3 with each pair
comprising one connectivity construct in each direction.
King, et al. Expires 1 March 2025 [Page 11]
Internet-Draft ACTN and Network Slicing August 2024
(Customer VPL Request)
Boundary :
Between . . . . . . . . .:. . . . . . . . . . .
Customer & :
Network Operator : CMI
:
+-----------------------------+
| MDSC (Service Orchestrator) |
+-----------------------------+
Boundary :
Between . . . . . . . . .:. . . . . . . . . . .
Consumer & :
Network Provider : XMI
:
+-----------------------------+
| MDSC (Network Orchestrator) |
+-----------------------------+
:
: MPI
:
-----
| PNC |
Site A ( ----- ) Site B
+-----+ ( ) +-----+
| CE1 |========( Physical )========| CE2 |
+-----\ ( Network ) /-----+
\ (_______) /
\ || /
\ || /
VPL1 \ || / VPL2
\ || /
\ || /
\ || /
\-------------/
| CE3 |
+-------------+
Site C
Key: ... ACTN control connectivity
=== Physical connectivity
--- Logical connectivity
Figure 2: Virtual Private Line Model
King, et al. Expires 1 March 2025 [Page 12]
Internet-Draft ACTN and Network Slicing August 2024
3.4.2. ACTN Used for VPN Delivery Model
In the example shown in Figure 3, ACTN provides VPN connectivity
between two sites across three physical networks. The users of the
two sites express the requirements for the VPN. The request is
directed to the CNC, and the CNC interacts with the network
provider's MDSC. The main characteristics of this model are as
follows.
* Provides edge-to-edge VPN multi-access connectivity.
* Most of the function is managed by the network provider, with some
flexibility delegated to the customer-managed CNC.
In terms of the network slicing concept defined in [RFC9543], in this
example, the customer requests a single network slice with a pair of
point-to-point connectivity constructs (one in each direction)
between the service demarcation points at site A and site B. The
customer is unaware that the service is delivered over multiple
physical networks.
King, et al. Expires 1 March 2025 [Page 13]
Internet-Draft ACTN and Network Slicing August 2024
+--------------+ +--------------+
| CNC-A | | CNC-B |
+--------------+ +--------------+
: :
Boundary : :
Between . . . . . . . . ..:. . . . . . . . . . .
Consumer & : :
Network Operator : CMI-A : CMI-B
: :
+-----------------------------+
| MDSC (Service Orchestrator) |
+-----------------------------+
Boundary :
Between . . . . . . . . . . . : . . . . . . . . . .
Consumer & :
Network Provider : XMI
:
+-----------------------------+
| MDSC (Network Orchestrator) |
+-----------------------------+
: : :
: MPI : MPI : MPI
: : :
+-------+ +-------+ +-------+
| PNC | | PNC | | PNC |
+-------+ +-------+ +-------+
: : :
: : :
____ --------- --------- --------- ____
< > ( ) ( ) ( ) < >
<Site>==( Physical )==( Physical )==( Physical )==<Site>
< A > ( Network ) ( Network ) ( Network ) < B >
< > ( ) ( ) ( ) < >
< > ------- ------- ------- < >
< >-----------------------------------------------< >
<____> <____>
Key: ... ACTN control connectivity
=== Physical connectivity
--- Logical connectivity
Figure 3: VPN Model
King, et al. Expires 1 March 2025 [Page 14]
Internet-Draft ACTN and Network Slicing August 2024
3.4.3. ACTN Used to Deliver a Virtual Customer Network
In the example shown in Figure 4, ACTN provides a virtual network to
the customer. This virtual network is managed by the customer. The
figure shows two virtual networks (Network Slice 1 and Network Slice
2) each created for different customers under the care of different
CNCs. There are two physical networks controlled by separate PNCs.
Network Slice 2 is built using resources from just one physical
network, while Network Slice 1 is constructed using resources from
both physical networks.
The characteristics of this model include the following.
* The MDSC provides the topology to the customer so that the
customer can control their network slice to fit their needs.
* Customers may interact with their assigned network slices
directly. The customer may implement their own network control
methods and traffic classification, mapping, prioritization, and
manage their own addressing schemes.
* Customers may further slice their virtual networks so that this
becomes a recursive model.
* Service isolation can be provided through selection of physical
networking resources through a combination of efforts of the MSDC
and PNC.
* The network slice may include nodes with specific capabilities.
These can be delivered as Physical Network Functions (PNFs) or
Virtual Network Functions (VNFs).
King, et al. Expires 1 March 2025 [Page 15]
Internet-Draft ACTN and Network Slicing August 2024
+--------------+ ___________
| Service | ( )
| Orchestrator |---------------->( Network )
+--------------+ ( Slice 2 )
^ (___________)
| ___________ ^
| +--------------+ ( ) :
| | Service |------->( Network ) :
| | Orchestrator | ( Slice 1 ) :
| +--------------+ (___________) :
| ^ ^ ^ :
Boundary | | : : :
Between .|. . . .|. . . . . . . . . . . : . .:. . : . . .
Consumer & | | : : :
Network | | : : :
Provider v v : : :
+---------------+ : :....:
| MDSC | : :
| (Network | : :
| Orchestrator) | : :
+---------------+ : :
^ ------^-- :
| ( ) :
v ( Physical ) :
+-------+ ( Network ) :
| PNC |<------------>( ) ---^-----
+------- | ------- ( )
| PNC |-+ ( Physical )
| |<-------------------------->( Network )
+-------+ ( )
-------
Key: --- ACTN control connection
... Virtualization/abstraction through slicing
Figure 4: Network Slicing
4. YANG Models
4.1. Network Slice Service Mapping from TE to ACTN VN Models
The TE-service mapping model [I-D.ietf-teas-te-service-mapping-yang]
creates a binding relationship across a L3VPN Service Model (L3SM)
[RFC8299], L2VPN Service Model (L2SM) [RFC8466], and TE Tunnel model
[I-D.ietf-teas-yang-te], via the generic ACTN Virtual Network (VN)
model [I-D.ietf-teas-actn-vn-yang].
King, et al. Expires 1 March 2025 [Page 16]
Internet-Draft ACTN and Network Slicing August 2024
When necessary, it must be possible to map between a slice service
request and an ACTN VN model. The ACTN VN model is a generic virtual
network service model that allows customers to specify a VN that
meets the customer's service objectives with various constraints,
which could be included in the initial request, and how the service
is delivered. Therefore, a request for a network slice service may
be mapped directly to a request for a VN.
The TE-service mapping model [I-D.ietf-teas-te-service-mapping-yang]
binds the L3SM with TE-specific parameters. This binding facilitates
seamless service operation and enables visibility of the underlay TE
network. The TE-service model developed in that document can also be
extended to support other services, including L2SM, and the Layer 1
Connectivity Service Model (L1CSM) [I-D.ietf-ccamp-l1csm-yang] L1CSM
network service models.
Figure 5 shows the relationship between the YANG models discussed
above.
--------------- -----------
| L3SM |<=========| | -----------
--------------- augments| |..........>| ACTN VN |
--------------- | Augmented |references -----------
| L2SM |<=========| Service |
--------------- augments| Model | -----------
--------------- | |..........>| TE-topo |
| L1CSM |<=========| |references -----------
--------------- augments| |
--------------- | | -----------
| TE & Service |--------->| |..........>| TE-tunnel |
| Mapping Types | import ----------- references -----------
---------------
Figure 5: Relationships Between YANG Models
Work is still needed to define YANG models to help map network slice
services to Traffic Engineering (TE) models. For example,
[I-D.dhody-teas-ietf-network-slice-mapping] shows how the Virtual
Network (VN) model and the TE Tunnel model can support network slice
services.
King, et al. Expires 1 March 2025 [Page 17]
Internet-Draft ACTN and Network Slicing August 2024
4.2. Interfaces and YANG Models
Figure 6 shows the two ACTN components (MDSC and PNC) and one ACTN
interface (MPI), as listed in Section 3. The figure also shows the
Device Configuration Interface between the PNC and the devices in the
physical network. That interface might be used to install state on
every device in the network, or might instruct a "head-end" node when
a control plane is used within the physical network. In the context
of [RFC8309], the Device Configuration Interface uses one or more
device configuration models.
Figure 6 also shows the Network Slice Service Interface. This
interface allows a customer to make requests for delivery of the
service, and it facilitates the customer modifying and monitoring the
service. In the context of [RFC8309], this is a customer service
interface and uses a service model.
When an ACTN system is used to manage the delivery of network slices,
a network slice resource model is needed. This model will be used
for instantiation, operation, and monitoring of network and function
resource slices. The YANG model defined in
[I-D.ietf-teas-ietf-network-slice-nbi-yang] provides a suitable basis
for requesting, controlling, and deletion, of a Network Slice
Service.
King, et al. Expires 1 March 2025 [Page 18]
Internet-Draft ACTN and Network Slicing August 2024
+----------+
| Consumer |
+----------+
:
.......:....... Network Slice Service Interface
:
+---------------+
| MDSC |
+---------------+
:
.......:....... MPI
:
+-------+
| PNC |
+-------+
:
.......:....... Device Configuration Interface
:
----------
( )
( Physical )
( Network )
(________)
Figure 6: The YANG Interfaces in Context
4.3. ACTN VN Telemetry
The ACTN VN telemetry model
[I-D.ietf-teas-actn-pm-telemetry-autonomics] provides a way for a
customer to define performance monitoring relevant for the VN/network
slice via the NETCONF subscription mechanisms [RFC8639], [RFC8640],
or using the equivalent mechanisms in RESTCONF [RFC8641], [RFC8650].
Key characteristics of [I-D.ietf-teas-actn-pm-telemetry-autonomics]
include the following:
* An ability to provide scalable VN-level telemetry aggregation
based on a customer subscription model for key performance
parameters defined by the customer.
* An ability to facilitate proactive re-optimization and
reconfiguration of VNs/network slices based on autonomic network
traffic engineering scaling configuration mechanisms.
King, et al. Expires 1 March 2025 [Page 19]
Internet-Draft ACTN and Network Slicing August 2024
5. IANA Considerations
This document makes no requests for action by IANA.
6. Security Considerations
Network slicing involves the control of network resources in order to
meet the service requirements of customers. In some deployment
models using ACTN, the customer may directly request a modification
in the behaviour of resources owned and operated by a service
provider. Such changes could significantly affect the service
provider's ability to provide services to other customers.
Furthermore, the resources allocated for or consumed by a customer
will typically be billable by the service provider.
Therefore, it is crucial that the mechanisms used in any network
slicing system allow for authentication of requests, security of
those requests, and tracking of resource allocations.
It should also be noted that while the partitioning or slicing of
resources is virtual, as mentioned in Section 2.3 the customers
expect and require that there is no risk of data leakage from one
slice to another, and no transfer of knowledge of the structure or
even existence of other slices. Further, in some service requests,
there is an expectation that changes to one slice (under the control
of one customer) should not have detrimental effects on the operation
of other slices (whether under control of different or the same
customers) even within limits allowed within the SLA. Thus, slices
are assumed to be private and to provide the appearance of genuine
physical connectivity.
Some service provider's may offer secure network slices as a service.
Such services may claim to include edge-to-edge encryption for the
customer's traffic. However, a customer should take full
responsibility for the privacy and integrity of their traffic and
should carefully consider using their own edge-to-edge encryption.
Further security considerations and recommendations may be found in
Section 9 of [RFC8453] and Section 10 of [RFC9543], with the latter
document providing additional privacy considerations in Section 11.
ACTN operates using the NETCONF [RFC6241] or RESTCONF [RFC8040]
protocols and assumes the security characteristics of those
protocols. Deployment models for ACTN should fully explore the
authentication and other security aspects before networks start to
carry live traffic.
King, et al. Expires 1 March 2025 [Page 20]
Internet-Draft ACTN and Network Slicing August 2024
7. Acknowledgements
Thanks to Italo Busi, Qin Wu, Andy Jones, Ramon Casellas, Gert
Grammel, Joe Clarke, Peter Yee, Alvaro Retana, Éric Vyncke, Linda
Dunbar and Kiran Makhijani for their reviews, insight, and useful
discussions about network slicing.
This work is partially supported by the European Commission under
Horizon 2020 grant agreement number 101015857 Secured autonomic
traffic management for a Tera of SDN flows (Teraflow).
8. Contributors
The following people contributed text to this document.
Young Lee
Email: younglee.tx@gmail.com
Mohamed Boucadair
Email: mohamed.boucadair@orange.com
Sergio Belotti
Email: sergio.belotti@nokia.com
Daniele Ceccarelli
Email: dceccare@cisco.com
9. Normative References
[I-D.ietf-teas-actn-pm-telemetry-autonomics]
Lee, Y., Dhody, D., Vilalta, R., King, D., and D.
Ceccarelli, "YANG models for Virtual Network (VN)/TE
Performance Monitoring Telemetry and Scaling Intent
Autonomics", Work in Progress, Internet-Draft, draft-ietf-
teas-actn-pm-telemetry-autonomics-12, 16 March 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-teas-
actn-pm-telemetry-autonomics-12>.
[I-D.ietf-teas-actn-vn-yang]
Lee, Y., Dhody, D., Ceccarelli, D., Bryskin, I., and B. Y.
Yoon, "A YANG Data Model for Virtual Network (VN)
Operations", Work in Progress, Internet-Draft, draft-ietf-
teas-actn-vn-yang-29, 22 June 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-teas-
actn-vn-yang-29>.
King, et al. Expires 1 March 2025 [Page 21]
Internet-Draft ACTN and Network Slicing August 2024
[I-D.ietf-teas-enhanced-vpn]
Dong, J., Bryant, S., Li, Z., Miyasaka, T., and Y. Lee, "A
Framework for Network Resource Partition (NRP) based
Enhanced Virtual Private Networks", Work in Progress,
Internet-Draft, draft-ietf-teas-enhanced-vpn-20, 14 June
2024, <https://datatracker.ietf.org/doc/html/draft-ietf-
teas-enhanced-vpn-20>.
[I-D.ietf-teas-ietf-network-slice-nbi-yang]
Wu, B., Dhody, D., Rokui, R., Saad, T., and J. Mullooly,
"A YANG Data Model for the RFC 9543 Network Slice
Service", Work in Progress, Internet-Draft, draft-ietf-
teas-ietf-network-slice-nbi-yang-15, 27 August 2024,
<https://datatracker.ietf.org/api/v1/doc/document/draft-
ietf-teas-ietf-network-slice-nbi-yang/>.
[I-D.ietf-teas-te-service-mapping-yang]
Lee, Y., Dhody, D., Fioccola, G., Wu, Q., Ceccarelli, D.,
and J. Tantsura, "Traffic Engineering (TE) and Service
Mapping YANG Data Model", Work in Progress, Internet-
Draft, draft-ietf-teas-te-service-mapping-yang-15, 16
March 2024, <https://datatracker.ietf.org/doc/html/draft-
ietf-teas-te-service-mapping-yang-15>.
[I-D.ietf-teas-yang-te]
Saad, T., Gandhi, R., Liu, X., Beeram, V. P., and I.
Bryskin, "A YANG Data Model for Traffic Engineering
Tunnels, Label Switched Paths and Interfaces", Work in
Progress, Internet-Draft, draft-ietf-teas-yang-te-36, 2
February 2024, <https://datatracker.ietf.org/doc/html/
draft-ietf-teas-yang-te-36>.
[RFC8299] Wu, Q., Ed., Litkowski, S., Tomotaki, L., and K. Ogaki,
"YANG Data Model for L3VPN Service Delivery", RFC 8299,
DOI 10.17487/RFC8299, January 2018,
<https://www.rfc-editor.org/info/rfc8299>.
[RFC8453] Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for
Abstraction and Control of TE Networks (ACTN)", RFC 8453,
DOI 10.17487/RFC8453, August 2018,
<https://www.rfc-editor.org/info/rfc8453>.
[RFC8466] Wen, B., Fioccola, G., Ed., Xie, C., and L. Jalil, "A YANG
Data Model for Layer 2 Virtual Private Network (L2VPN)
Service Delivery", RFC 8466, DOI 10.17487/RFC8466, October
2018, <https://www.rfc-editor.org/info/rfc8466>.
King, et al. Expires 1 March 2025 [Page 22]
Internet-Draft ACTN and Network Slicing August 2024
[RFC9543] Farrel, A., Ed., Drake, J., Ed., Rokui, R., Homma, S.,
Makhijani, K., Contreras, L., and J. Tantsura, "A
Framework for Network Slices in Networks Built from IETF
Technologies", RFC 9543, DOI 10.17487/RFC9543, March 2024,
<https://www.rfc-editor.org/info/rfc9543>.
10. Informative References
[I-D.dhody-teas-ietf-network-slice-mapping]
Dhody, D. and B. Wu, "IETF Network Slice Service Mapping
YANG Model", Work in Progress, Internet-Draft, draft-
dhody-teas-ietf-network-slice-mapping-05, 5 July 2024,
<https://datatracker.ietf.org/doc/html/draft-dhody-teas-
ietf-network-slice-mapping-05>.
[I-D.ietf-ccamp-l1csm-yang]
Lee, Y., Lee, K., Zheng, H., de Dios, O. G., and D.
Ceccarelli, "A YANG Data Model for L1 Connectivity Service
Model (L1CSM)", Work in Progress, Internet-Draft, draft-
ietf-ccamp-l1csm-yang-26, 11 April 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-ccamp-
l1csm-yang-26>.
[I-D.ietf-teas-nrp-scalability]
Dong, J., Li, Z., Gong, L., Yang, G., and G. S. Mishra,
"Scalability Considerations for Network Resource
Partition", Work in Progress, Internet-Draft, draft-ietf-
teas-nrp-scalability-05, 5 July 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-teas-
nrp-scalability-05>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665,
DOI 10.17487/RFC7665, October 2015,
<https://www.rfc-editor.org/info/rfc7665>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8309] Wu, Q., Liu, W., and A. Farrel, "Service Models
Explained", RFC 8309, DOI 10.17487/RFC8309, January 2018,
<https://www.rfc-editor.org/info/rfc8309>.
King, et al. Expires 1 March 2025 [Page 23]
Internet-Draft ACTN and Network Slicing August 2024
[RFC8454] Lee, Y., Belotti, S., Dhody, D., Ceccarelli, D., and B.
Yoon, "Information Model for Abstraction and Control of TE
Networks (ACTN)", RFC 8454, DOI 10.17487/RFC8454,
September 2018, <https://www.rfc-editor.org/info/rfc8454>.
[RFC8639] Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard,
E., and A. Tripathy, "Subscription to YANG Notifications",
RFC 8639, DOI 10.17487/RFC8639, September 2019,
<https://www.rfc-editor.org/info/rfc8639>.
[RFC8640] Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard,
E., and A. Tripathy, "Dynamic Subscription to YANG Events
and Datastores over NETCONF", RFC 8640,
DOI 10.17487/RFC8640, September 2019,
<https://www.rfc-editor.org/info/rfc8640>.
[RFC8641] Clemm, A. and E. Voit, "Subscription to YANG Notifications
for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641,
September 2019, <https://www.rfc-editor.org/info/rfc8641>.
[RFC8650] Voit, E., Rahman, R., Nilsen-Nygaard, E., Clemm, A., and
A. Bierman, "Dynamic Subscription to YANG Events and
Datastores over RESTCONF", RFC 8650, DOI 10.17487/RFC8650,
November 2019, <https://www.rfc-editor.org/info/rfc8650>.
[RFC9182] Barguil, S., Gonzalez de Dios, O., Ed., Boucadair, M.,
Ed., Munoz, L., and A. Aguado, "A YANG Network Data Model
for Layer 3 VPNs", RFC 9182, DOI 10.17487/RFC9182,
February 2022, <https://www.rfc-editor.org/info/rfc9182>.
[RFC9291] Boucadair, M., Ed., Gonzalez de Dios, O., Ed., Barguil,
S., and L. Munoz, "A YANG Network Data Model for Layer 2
VPNs", RFC 9291, DOI 10.17487/RFC9291, September 2022,
<https://www.rfc-editor.org/info/rfc9291>.
[RFC9522] Farrel, A., Ed., "Overview and Principles of Internet
Traffic Engineering", RFC 9522, DOI 10.17487/RFC9522,
January 2024, <https://www.rfc-editor.org/info/rfc9522>.
Authors' Addresses
Daniel King
Old Dog Consulting
Email: daniel@olddog.co.uk
John Drake
Independent
King, et al. Expires 1 March 2025 [Page 24]
Internet-Draft ACTN and Network Slicing August 2024
Email: je_drake@yahoo.com
Haomian Zheng
Huawei Technologies
Email: zhenghaomian@huawei.com
Adrian Farrel
Old Dog Consulting
Email: adrian@olddog.co.uk
King, et al. Expires 1 March 2025 [Page 25]
