draft-nsdt-teas-ietf-network-slice-definition-01.txt   draft-nsdt-teas-ietf-network-slice-definition-02.txt 
teas R. Rokui teas R. Rokui
Internet-Draft Nokia Internet-Draft Nokia
Intended status: Informational S. Homma Intended status: Informational S. Homma
Expires: May 6, 2021 NTT Expires: June 14, 2021 NTT
K. Makhijani K. Makhijani
Futurewei Futurewei
LM. Contreras LM. Contreras
Telefonica Telefonica
J. Tantsura J. Tantsura
Apstra, Inc. Apstra, Inc.
November 2, 2020 December 11, 2020
Definition of IETF Network Slices Definition of IETF Network Slices
draft-nsdt-teas-ietf-network-slice-definition-01 draft-nsdt-teas-ietf-network-slice-definition-02
Abstract Abstract
This document provides a definition of the term "IETF Network Slice" This document provides a definition of the term "IETF Network Slice"
for use within the IETF and specifically as a reference for other for use within the IETF and specifically as a reference for other
IETF documents that describe or use aspects of network slices. IETF documents that describe or use aspects of network slices.
The document also describes the characteristics of an IETF network The document also describes the characteristics of an IETF network
slice, related terms and their meanings, and explains how IETF slice, related terms and their meanings, and explains how IETF
network slices can be used in combination with end-to-end network network slices can be used in combination with end-to-end network
skipping to change at page 1, line 44 skipping to change at page 1, line 44
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 6, 2021. This Internet-Draft will expire on June 14, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Rationale . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terms and Abbreviations . . . . . . . . . . . . . . . . . . . 3
2. Terms and Abbreviations . . . . . . . . . . . . . . . . . . . 4
3. Definition and Scope of IETF Network Slice . . . . . . . . . 4 3. Definition and Scope of IETF Network Slice . . . . . . . . . 4
4. IETF Network Slice System Characteristics . . . . . . . . . . 5 4. IETF Network Slice System Characteristics . . . . . . . . . . 4
4.1. Objectives for IETF Network Slices . . . . . . . . . . . 5 4.1. Objectives for IETF Network Slices . . . . . . . . . . . 5
4.1.1. Service Level Objectives . . . . . . . . . . . . . . 5 4.1.1. Service Level Objectives . . . . . . . . . . . . . . 5
4.1.2. Minimal Set of SLOs . . . . . . . . . . . . . . . . . 6 4.1.2. Minimal Set of SLOs . . . . . . . . . . . . . . . . . 5
4.1.3. Other Objectives . . . . . . . . . . . . . . . . . . 7 4.1.3. Other Objectives . . . . . . . . . . . . . . . . . . 7
4.2. IETF Network Slice Endpoints . . . . . . . . . . . . . . 7 4.2. IETF Network Slice Endpoints . . . . . . . . . . . . . . 7
4.2.1. IETF Network Slice Connectivity Types . . . . . . . . 9 4.2.1. IETF Network Slice Connectivity Types . . . . . . . . 9
4.3. IETF Network Slice Composition . . . . . . . . . . . . . 9 4.3. IETF Network Slice Composition . . . . . . . . . . . . . 9
5. IETF Network Slice Structure . . . . . . . . . . . . . . . . 10 5. IETF Network Slice Structure . . . . . . . . . . . . . . . . 10
6. IETF Network Slice Stakeholders . . . . . . . . . . . . . . . 11 6. IETF Network Slice Stakeholders . . . . . . . . . . . . . . . 11
7. IETF Network Slice Controller Interfaces . . . . . . . . . . 12 7. IETF Network Slice Controller Interfaces . . . . . . . . . . 12
8. Realizing IETF Network Slice . . . . . . . . . . . . . . . . 12 8. Realizing IETF Network Slice . . . . . . . . . . . . . . . . 12
9. Isolation in IETF Network Slices . . . . . . . . . . . . . . 13 9. Isolation in IETF Network Slices . . . . . . . . . . . . . . 13
9.1. Isolation as a Service Requirement . . . . . . . . . . . 13 9.1. Isolation as a Service Requirement . . . . . . . . . . . 13
9.2. Isolation in IETF Network Slice Realization . . . . . . . 14 9.2. Isolation in IETF Network Slice Realization . . . . . . . 13
9.3. Relationship with Isolation in 5G Network Slice . . . . . 14
10. Security Considerations . . . . . . . . . . . . . . . . . . . 14 10. Security Considerations . . . . . . . . . . . . . . . . . . . 14
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
12. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 15 12. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 15
13. Informative References . . . . . . . . . . . . . . . . . . . 15 13. Informative References . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction 1. Introduction
A number of use cases benefit from network connections that along A number of use cases benefit from network connections that along
with the connectivity provide assurance of meeting a specific set of with the connectivity provide assurance of meeting a specific set of
objectives wrt network resources use. In this document, as detailed objectives wrt network resources use. In this document, as detailed
in the subsequent sections, we refer to this connectivity and in the subsequent sections, we refer to this connectivity and
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o 5G services (e.g. eMBB, URLLC, mMTC)(See [TS.23.501-3GPP]) o 5G services (e.g. eMBB, URLLC, mMTC)(See [TS.23.501-3GPP])
o Network wholesale services o Network wholesale services
o Network infrastructure sharing among operators o Network infrastructure sharing among operators
o NFV connectivity and Data Center Interconnect o NFV connectivity and Data Center Interconnect
The use cases are further described in [I-D.nsdt-teas-ns-framework]. The use cases are further described in [I-D.nsdt-teas-ns-framework].
This document defines the concept of IETF Network Slices that provide This document defines the concept of IETF network slices that provide
connectivity coupled with a set of specific commitments of network connectivity coupled with a set of specific commitments of network
resources between a number of endpoints over a shared network resources between a number of endpoints over a shared network
infrastructure. Since the term network slice is rather generic, the infrastructure. Since the term network slice is rather generic, the
qualifying term 'IETF' is used in this document to limit the scope of qualifying term 'IETF' is used in this document to limit the scope of
network slice to network technologies described and standardized by network slice to network technologies described and standardized by
the IETF. the IETF.
1.1. Rationale IETF network slices are created and managed within the scope of one
IETF Network Slices are created and managed within the scope of one
or more network technologies (e.g., IP, MPLS, optical). They are or more network technologies (e.g., IP, MPLS, optical). They are
intended to enable a diverse set of applications that have different intended to enable a diverse set of applications that have different
requirements to coexist on the same network infrastructure. requirements to coexist on the same network infrastructure. A
request for an IETF network slice is technology-agnostic so as to
An IETF Network Slice is a well-defined structure of connectivity allow a consumer to describe their network connectivity objectives in
requirements and associated network behaviors. IETF Network Slices a common format, independent of the underlying technologies used.
are defined such that they are independent of the underlying
infrastructure connectivity and technologies used. This is to allow
an IETF Network Slice consumer to describe their network connectivity
and relevant objectives in a common format, independent of the
underlying technologies used.
IETF Network Slices may be combined hierarchically, so that a network
slice may itself be sliced. They may also be combined sequentially
so that various different networks can each be sliced and the network
slices placed into a sequence to provide an end-to-end service. This
form of sequential combination is utilized in some services such as
in 3GPP's 5G network [TS.23.501-3GPP].
2. Terms and Abbreviations 2. Terms and Abbreviations
The terms and abbreviations used in this document are listed below. The terms and abbreviations used in this document are listed below.
o NS: Network Slice o NS: Network Slice
o NSC: Network Slice Controller o NSC: Network Slice Controller
o NBI: NorthBound Interface o NBI: NorthBound Interface
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o NBI: NorthBound Interface o NBI: NorthBound Interface
o SBI: SouthBound Interface o SBI: SouthBound Interface
o SLI: Service Level Indicator o SLI: Service Level Indicator
o SLO: Service Level Objective o SLO: Service Level Objective
o SLA: Service Level Agreement o SLA: Service Level Agreement
The above terminology is defined in greater details in the remainder The above terminology is defined in greater details in the remainder
of this document. of this document.
3. Definition and Scope of IETF Network Slice 3. Definition and Scope of IETF Network Slice
The definition of a network slice in IETF context is as follows: The definition of a network slice in IETF context is as follows:
An IETF Network Slice is a logical network topology connecting a An IETF network slice is a logical network topology connecting a
number of endpoints with a set of shared or dedicated network number of endpoints using a set of shared or dedicated network
resources, that are used to satisfy specific Service Level Objectives resources that are used to satisfy specific Service Level Objectives
(SLOs). (SLOs).
IETF Network Slice specification is technology-agnostic, and the An IETF network slice combines the connectivity resource requirements
means for IETF network slice realization can be chosen depending on and associated network behaviors such as bandwidth, latency, jitter,
several factors such as: service requirements, specifications or and network functions with other resource behaviors such as compute
capabilities of underlying infrastructure. The structure and and storage availability. IETF network slices are independent of the
different characteristics of IETF Network Slices are described in the underlying infrastructure connectivity and technologies used. This
following sections. is to allow an IETF network slice consumer to describe their network
connectivity and relevant objectives in a common format, independent
of the underlying technologies used.
IETF network slices may be combined hierarchically, so that a network
slice may itself be sliced. They may also be combined sequentially
so that various different networks can each be sliced and the network
slices placed into a sequence to provide an end-to-end service. This
form of sequential combination is utilized in some services such as
in 3GPP's 5G network [TS.23.501-3GPP].
An IETF network slice is technology-agnostic, and the means for IETF
network slice realization can be chosen depending on several factors
such as: service requirements, specifications or capabilities of
underlying infrastructure. The structure and different
characteristics of IETF network slices are described in the following
sections.
Term "Slice" refers to a set of characteristics and behaviours that Term "Slice" refers to a set of characteristics and behaviours that
separate one type of user-traffic from another. IETF Network Slice separate one type of user-traffic from another. IETF network slice
assumes that an underlying network is capable of changing the assumes that an underlying network is capable of changing the
configurations of the network devices on demand, through in-band configurations of the network devices on demand, through in-band
signaling or via controller(s) and fulfilling all or some of SLOs to signaling or via controller(s) and fulfilling all or some of SLOs to
all of the traffic in the slice or to specific flows. all of the traffic in the slice or to specific flows.
4. IETF Network Slice System Characteristics 4. IETF Network Slice System Characteristics
The following subsections describe the characteristics of IETF The following subsections describe the characteristics of IETF
network slices. network slices.
4.1. Objectives for IETF Network Slices 4.1. Objectives for IETF Network Slices
An IETF Network Slice is defined in terms of several quantifiable An IETF network slice is defined in terms of several quantifiable
characteristics or service level objectives (SLOs). SLOs along with characteristics or service level objectives (SLOs). SLOs along with
terms Service Level Indicator (SLI) and Service Level Agreement (SLA) terms Service Level Indicator (SLI) and Service Level Agreement (SLA)
are used to define the performance of a service at different levels. are used to define the performance of a service at different levels.
A Service Level Indicator (SLI) is a quantifiable measure of an A Service Level Indicator (SLI) is a quantifiable measure of an
aspect of the performance of a network. For example, it may be a aspect of the performance of a network. For example, it may be a
measure of throughput in bits per second, or it may be a measure of measure of throughput in bits per second, or it may be a measure of
latency in milliseconds. latency in milliseconds.
A Service Level Objective (SLO) is a target value or range for the A Service Level Objective (SLO) is a target value or range for the
measurements returned by observation of an SLI. For example, an SLO measurements returned by observation of an SLI. For example, an SLO
may be expressed as "SLI <= target", or "lower bound <= SLI <= upper may be expressed as "SLI <= target", or "lower bound <= SLI <= upper
bound". A network slice is expressed in terms of the set of SLOs bound". A network slice is expressed in terms of the set of SLOs
that are to be delivered for the different connections between that are to be delivered for the different connections between
endpoints. endpoints.
A Service Level Agreement (SLA) is an explicit or implicit contract A Service Level Agreement (SLA) is an explicit or implicit contract
between the consumer of an IETF Network Slice and the provider of the between the consumer of an IETF network slice and the provider of the
slice. The SLA is expressed in terms of a set of SLOs and may slice. The SLA is expressed in terms of a set of SLOs and may
include commercial terms as well as the consequences of missing/ include commercial terms as well as the consequences of missing/
violating the SLOs they contain. violating the SLOs they contain.
Additional descriptions of IETF network slice attributes is covered Additional descriptions of IETF network slice attributes is covered
in [I-D.contreras-teas-slice-nbi]. in [I-D.contreras-teas-slice-nbi].
4.1.1. Service Level Objectives 4.1.1. Service Level Objectives
SLOs define a set of network attributes and characteristics that SLOs define a set of network attributes and characteristics that
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SLOs can be categorized in to 'Directly Measurable Objectives' or SLOs can be categorized in to 'Directly Measurable Objectives' or
'Indirectly Measurable Objectives'. Objectives such as guaranteed 'Indirectly Measurable Objectives'. Objectives such as guaranteed
minimum bandwidth, guaranteed maximum latency, maximum permissible minimum bandwidth, guaranteed maximum latency, maximum permissible
delay variation, maximum permissible packet loss rate, and delay variation, maximum permissible packet loss rate, and
availability are 'Directly Measurable Objectives'. While 'Indirectly availability are 'Directly Measurable Objectives'. While 'Indirectly
Measurable Objectives' include security, geographical restrictions, Measurable Objectives' include security, geographical restrictions,
maximum occupancy level objectives. The later standard might define maximum occupancy level objectives. The later standard might define
other SLOs as needed. other SLOs as needed.
Editor's Note TODO: Minimal set describes most commonly used Editor's Note TODO: replace Minimal set to most commonly used
objectives to describe network behavior. Other directly or objectives to describe network behavior. Other directly or
indirectly measurable objectives may be requested by that customer of indirectly measurable objectives may be requested by that consumer of
an IETF network slice. an IETF network slice.
The definition of these objectives are as follows: The definition of these objectives are as follows:
Guaranteed Minimum Bandwidth Guaranteed Minimum Bandwidth
Minimum guaranteed bandwidth between two endpoints at any time. Minimum guaranteed bandwidth between two endpoints at any time.
The bandwidth is measured in data rate units of bits per second The bandwidth is measured in data rate units of bits per second
and is measured unidirectionally. and is measured unidirectionally.
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difference in the one-way delay between sequential packets in a difference in the one-way delay between sequential packets in a
flow. This SLO sets a maximum value PDV for packets between flow. This SLO sets a maximum value PDV for packets between
two endpoints. two endpoints.
Maximum permissible packet loss rate Maximum permissible packet loss rate
The ratio of packets dropped to packets transmitted between two The ratio of packets dropped to packets transmitted between two
endpoints over a period of time. See [RFC7680] endpoints over a period of time. See [RFC7680]
Availability Availability
The ratio of uptime to the sum of uptime and downtime, where The ratio of uptime to the sum of uptime and downtime, where
uptime is the time the IETF network slice is available in uptime is the time the IETF network slice is available in
accordance with the SLOs associated with it. accordance with the SLOs associated with it.
Security Security
An IETF Network Slice consumer may request that the network An IETF network slice consumer may request that the network
applies encryption or other security techniques to traffic applies encryption or other security techniques to traffic
flowing between endpoints. flowing between endpoints.
Note that the use of security or the violation of this SLO is Note that the use of security or the violation of this SLO is
not directly observable by the IETF Network Slice consumer and not directly observable by the IETF network slice consumer and
cannot be measured as a quantifiable metric. cannot be measured as a quantifiable metric.
Also note that the objective may include request for encryption Also note that the objective may include request for encryption
(e.g., [RFC4303]) between the two endpoints explicitly to meet (e.g., [RFC4303]) between the two endpoints explicitly to meet
architecture recommendations as in [TS33.210] or for compliance architecture recommendations as in [TS33.210] or for compliance
with [HIPAA] and/or [PCI]. with [HIPAA] and/or [PCI].
Editor's Note: Please see more discussion on security in Editor's Note: Please see more discussion on security in
Section 10. Section 10.
4.1.3. Other Objectives 4.1.3. Other Objectives
Additional SLOs may be defined to provide additional description of Additional SLOs may be defined to provide additional description of
the IETF network slice that a consumer requests. the IETF network slice that a consumer requests.
If the IETF Network Slice consumer service is traffic aware, other If the IETF network slice consumer service is traffic aware, other
traffic specific characteristics may be valuable including MTU, traffic specific characteristics may be valuable including MTU,
traffic-type (e.g., IPv4, IPv6, Ethernet or unstructured), or a traffic-type (e.g., IPv4, IPv6, Ethernet or unstructured), or a
higher-level behavior to process traffic according to user- higher-level behavior to process traffic according to user-
application (which may be realized using network functions). application (which may be realized using network functions).
Maximal occupancy for an IETF network slice should be provided. Maximal occupancy for an IETF network slice should be provided.
Since it carries traffic for multiple flows between the two Since it carries traffic for multiple flows between the two
endpoints, the objectives should also say if they are for the entire endpoints, the objectives should also say if they are for the entire
connection, group of flows or on per flow basis. Maximal occupancy connection, group of flows or on per flow basis. Maximal occupancy
should specify the scale of the flows (i.e. maximum number of flows should specify the scale of the flows (i.e. maximum number of flows
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4.2. IETF Network Slice Endpoints 4.2. IETF Network Slice Endpoints
As noted in Section 3, an IETF network slice describes connectivity As noted in Section 3, an IETF network slice describes connectivity
between endpoints across the underlying network. This connectivity between endpoints across the underlying network. This connectivity
may be be point-to-point, point-to-multipoint (P2MP), multipoint-to- may be be point-to-point, point-to-multipoint (P2MP), multipoint-to-
point, or multipoint-to-multipoint. point, or multipoint-to-multipoint.
The characteristics of IETF network slice endpoints (NSEs) are as The characteristics of IETF network slice endpoints (NSEs) are as
follows. follows.
o They are conceptual points of connection of a customer network, o They are conceptual points of connection of a consumer network,
network function, device, or application to the IETF network network function, device, or application to the IETF network
slice. This might include routers, switches, firewalls, WAN, slice. This might include routers, switches, firewalls, WAN,
4G/5G RAN nodes, 4G/5G Core nodes, application acceleration, Deep 4G/5G RAN nodes, 4G/5G Core nodes, application acceleration, Deep
Packet Inspection (DPI), server load balancers, NAT44 [RFC3022], Packet Inspection (DPI), server load balancers, NAT44 [RFC3022],
NAT64 [RFC6146], HTTP header enrichment functions, and TCP NAT64 [RFC6146], HTTP header enrichment functions, and TCP
optimizers. optimizers.
o They are identified in a request provided by the consumer of an o They are identified in a request provided by the consumer of an
IETF Network Slice when the IETF Network Slice is requested. IETF network slice when the IETF network slice is requested.
o An NSE is identified a unique identifier and/or a unique name and o An NSE is identified a unique identifier and/or a unique name and
other data. A non-exhaustive list of other data includes IPv4 or other data. A non-exhaustive list of other data includes IPv4 or
IPv6 address, VLAN tag, port number, connectivity type (P2P, P2MP, IPv6 address, VLAN tag, port number, connectivity type (P2P, P2MP,
MP2MP). MP2MP).
Note that the NSE is different from access points (AP) defined in Note that the NSE is different from access points (AP) defined in
[RFC8453] as an AP is a logical identifier to identify the shared [RFC8453] as an AP is a logical identifier to identify the shared
link between the customer and the operator where as NSE is an link between the consumer and the operator where as NSE is an
identifier of an endpoint. Also NSE is different from TE Link identifier of an endpoint. Also NSE is different from TE Link
Termination Point (LTP) defined in [I-D.ietf-teas-yang-te-topo] as it Termination Point (LTP) defined in [I-D.ietf-teas-yang-te-topo] as it
is a conceptual point of connection of a TE node to one of the TE is a conceptual point of connection of a TE node to one of the TE
links on a TE node. links on a TE node.
The NSE is similar to the Termination Point (TP) defined in [RFC8345] The NSE is similar to the Termination Point (TP) defined in [RFC8345]
and can contain more attributes. NSE could be modeled by augmenting and can contain more attributes. NSE could be modeled by augmenting
the TP model. the TP model.
There is another type of the endpoints called "IETF Network Slice There is another type of the endpoints called "IETF Network Slice
Realization Endpoints (NSREs)". These endpoints are allocated and Realization Endpoints (NSREs)". These endpoints are allocated and
assigned by the network controller during the realization of an IETF assigned by the network controller during the realization of an IETF
Network Slice and are technology-specific, i.e. they depend on the network slice and are technology-specific, i.e. they depend on the
network technology used during the IETF Network Slice realization. network technology used during the IETF network slice realization.
The identification of NSREs forms part of the realization of the IETF The identification of NSREs forms part of the realization of the IETF
Network Slice and is implementation and deployment specific. network slice and is implementation and deployment specific.
Figure 1 shows an example of an IETF Network Slice and its Figure 1 shows an example of an IETF network slice and its
realization between multiple NSEs and NSREs. realization between multiple NSEs and NSREs.
(-------------------) (-------------------)
( IETF scoped Network ) ( IETF scoped Network )
DAN1 ( ) DAN2 DAN1 ( ) DAN2
-------- NSRE1 -------- -------- NSRE2 -------- -------- NSRE1 -------- -------- NSRE2 --------
| o |-------o| A | | B |o--------| o | | o |-------o| A | | B |o--------| o |
| NSE1| -------- -------- | NSE2 | | NSE1| -------- -------- | NSE2 |
-------- | ( ) | -------- -------- | ( ) | --------
| | ( ) | | | | ( ) | |
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4.2.1. IETF Network Slice Connectivity Types 4.2.1. IETF Network Slice Connectivity Types
The IETF Network Slice connection types can be point to point (P2P), The IETF Network Slice connection types can be point to point (P2P),
point to multipoint (P2MP), multi-point to point (MP2P), or multi- point to multipoint (P2MP), multi-point to point (MP2P), or multi-
point to multi-point (MP2MP). They will requested by the higher point to multi-point (MP2MP). They will requested by the higher
level operation system. level operation system.
4.3. IETF Network Slice Composition 4.3. IETF Network Slice Composition
Operationally, an IETF Network Slice maybe decomposed in two or more Operationally, an IETF network slice maybe decomposed in two or more
IETF Network Slices as specified below. Decomposed network slices IETF network slices as specified below. Decomposed network slices
are then independently realized and managed. are then independently realized and managed.
o Hierarchical (i.e., recursive) composition: An IETF Network Slice o Hierarchical (i.e., recursive) composition: An IETF network slice
can be further sliced into other network slices. Recursive can be further sliced into other network slices. Recursive
composition allows an IETF Network Slice at one layer to be used composition allows an IETF network slice at one layer to be used
by the other layers. This type of multi-layer vertical IETF by the other layers. This type of multi-layer vertical IETF
Network Slice associates resources at different layers. network slice associates resources at different layers.
o Sequential composition: Different IETF Network Slices can be o Sequential composition: Different IETF network slices can be
placed into a sequence to provide an end-to-end service. In placed into a sequence to provide an end-to-end service. In
sequential composition, each IETF Network Slice would potentially sequential composition, each IETF network slice would potentially
support different dataplanes that need to be stitched together. support different dataplanes that need to be stitched together.
5. IETF Network Slice Structure 5. IETF Network Slice Structure
Editor's note: This content of this section merged with Relationship Editor's note: This content of this section merged with Relationship
with E2E slice discussion. with E2E slice discussion.
An IETF Network Slice is a set of connections among various endpoints An IETF network slice is a set of connections among various endpoints
to form a logical network that meets the SLOs agreed upon. to form a logical network that meets the SLOs agreed upon.
____________________________ ____________________________
[EP11]------/ /--[EP21] [EP11]------/ /--[EP21]
/ / / /
[EP12]----/ IETF Network Slice /----[EP22] [EP12]----/ IETF Network Slice /----[EP22]
: / (SLOs e.g. / : / (SLOs e.g. /
: / B/W > x bps, Delay < y ms)/ : / B/W > x bps, Delay < y ms)/
[EP1m]-/___________________________/-------[EP2n] [EP1m]-/___________________________/-------[EP2n]
skipping to change at page 10, line 37 skipping to change at page 10, line 37
: `-----------' `-----------' : : `-----------' `-----------' :
[EP1m] [EP2n] [EP1m] [EP2n]
Legend Legend
SLOs in terms of attributes, e.g. BW, delay. SLOs in terms of attributes, e.g. BW, delay.
EP: Endpoint EP: Endpoint
B/W: Bandwidth B/W: Bandwidth
Figure 2: IETF Network slice Figure 2: IETF Network slice
Figure 2 illustrates a case where an IETF Network Slice provides Figure 2 illustrates a case where an IETF network slice provides
connectivity between a set of endpoints pairs with specific connectivity between a set of endpoints pairs with specific
characteristics for each SLO (e.g. guaranteed minimum bandwidth of x characteristics for each SLO (e.g. guaranteed minimum bandwidth of x
bps and guaranteed delay of no more than y ms). The endpoints may be bps and guaranteed delay of no more than y ms). The endpoints may be
distributed in the underlay networks, and an IETF Network Slice can distributed in the underlay networks, and an IETF network slice can
be deployed across multiple network domains. Also, the endpoints on be deployed across multiple network domains. Also, the endpoints on
the same IETF Network Slice may belong to the same or different the same IETF network slice may belong to the same or different
address spaces. address spaces.
IETF Network slice structure fits into a broader concept of end-to- IETF Network slice structure fits into a broader concept of end-to-
end network slices. A network operator may be responsible for end network slices. A network operator may be responsible for
delivering services over a number of technologies (such as radio delivering services over a number of technologies (such as radio
networks) and for providing specific and fine-grained services (such networks) and for providing specific and fine-grained services (such
as CCTV feed or High definition realtime traffic data). That as CCTV feed or High definition realtime traffic data). That
operator may need to combine slices of various networks to produce an operator may need to combine slices of various networks to produce an
end-to-end network service. Each of these networks may include end-to-end network service. Each of these networks may include
multiple physical or virtual nodes and may also provide network multiple physical or virtual nodes and may also provide network
functions beyond simply carrying of technology-specific protocol data functions beyond simply carrying of technology-specific protocol data
units.An end-to-end network slice is defined by the 3GPP as a units.An end-to-end network slice is defined by the 3GPP as a
complete logical network that provides a service in its entirety with complete logical network that provides a service in its entirety with
a specific assurance to the customer [TS.23.501-3GPP]. a specific assurance to the consumer [TS.23.501-3GPP].
An end-to-end network slice may be composed from other network slices An end-to-end network slice may be composed from other network slices
that include IETF Network Slices. This composition may include the that include IETF network slices. This composition may include the
hierarchical (or recursive) use of underlying network slices and the hierarchical (or recursive) use of underlying network slices and the
sequential (or stitched) combination of slices of different networks. sequential (or stitched) combination of slices of different networks.
6. IETF Network Slice Stakeholders 6. IETF Network Slice Stakeholders
An IETF Network Slice and its realization involves the following An IETF network slice and its realization involves the following
stakeholders and it is relevant to define them for consistent stakeholders and it is relevant to define them for consistent
terminology. terminology.
Consumer: A consumer is the requester of an IETF Network Slice. Consumer: A consumer is the requester of an IETF network slice.
Consumers may request monitoring of SLOs. A consumer may manage Consumers may request monitoring of SLOs. A consumer may manage
the IETF Network Slice service directly by interfacing with the the IETF network slice service directly by interfacing with the
IETF Network Slice controller or indirectly through an IETF network slice controller or indirectly through an
orchestrator. orchestrator.
Orchestrator: An orchestrator is an entity that composes different Orchestrator: An orchestrator is an entity that composes different
services, resource and network requirements. It interfaces with services, resource and network requirements. It interfaces with
the IETF Network Slice controllers. the IETF network slice controllers.
IETF Network Slice Controller (NSC): It realizes an IETF Network IETF Network Slice Controller (NSC): It realizes an IETF network
Slice in the underlying network, maintains and monitors the run- lice in the underlying network, maintains and monitors the run-
time state of resources and topologies associated with it. A time state of resources and topologies associated with it. A
well-defined interface is needed between different types of IETF well-defined interface is needed between different types of IETF
Network Slice controllers and different types of orchestrators. network slice controllers and different types of orchestrators.
An IETF Network Slice operator (or slice operator for short) An IETF network slice operator (or slice operator for short)
manages one or more IETF Network Slices using the IETF Network manages one or more IETF network slices using the IETF network
Slice Controller(s). slice Controller(s).
Network Controller: is a form of network infrastructure controller Network Controller: is a form of network infrastructure controller
that offers network resources to NSC to realize a particular that offers network resources to NSC to realize a particular
network slice. These may be existing network controllers network slice. These may be existing network controllers
associated with one or more specific technologies that may be associated with one or more specific technologies that may be
adapted to the function of realizing IETF Network Slices in a adapted to the function of realizing IETF network slices in a
network. network.
7. IETF Network Slice Controller Interfaces 7. IETF Network Slice Controller Interfaces
The interworking and interoperability among the different The interworking and interoperability among the different
stakeholders to provide common means of provisioning, operating and stakeholders to provide common means of provisioning, operating and
monitoring the IETF Network slices is enabled by the following monitoring the IETF Network slices is enabled by the following
communication interfaces (see Figure 3). communication interfaces (see Figure 3).
NSC Northbound Interface (NBI): The NSC Northbound Interface is an NSC Northbound Interface (NBI): The NSC Northbound Interface is an
interface between a consumer's higher level operation system interface between a consumer's higher level operation system
(e.g., a network slice orchestrator) and the NSC. It is a (e.g., a network slice orchestrator) and the NSC. It is a
technology agnostic interface. The consumer can use this technology agnostic interface. The consumer can use this
interface to communicate the requested characteristics and other interface to communicate the requested characteristics and other
requirements (i.e., the SLOs) for the IETF Network Slice, and the requirements (i.e., the SLOs) for the IETF network slice, and the
NSC can use the interface to report the operational state of an NSC can use the interface to report the operational state of an
IETF Network Slice to the consumer. IETF network slice to the consumer.
NSC Southbound Interface (SBI): The NSC Southbound Interface is an NSC Southbound Interface (SBI): The NSC Southbound Interface is an
interface between the NSC and network controllers. It is interface between the NSC and network controllers. It is
technology-specific and may be built around the many network technology-specific and may be built around the many network
models defined within the IETF. models defined within the IETF.
+------------------------------------------+ +------------------------------------------+
| Consumer higher level operation system | | Consumer higher level operation system |
| (e.g E2E network slice orchestrator) | | (e.g E2E network slice orchestrator) |
+------------------------------------------+ +------------------------------------------+
skipping to change at page 12, line 47 skipping to change at page 12, line 47
| NSC SBI | NSC SBI
V V
+------------------------------------------+ +------------------------------------------+
| Network Controllers | | Network Controllers |
+------------------------------------------+ +------------------------------------------+
Figure 3: Interface of IETF Network Slice Controller Figure 3: Interface of IETF Network Slice Controller
8. Realizing IETF Network Slice 8. Realizing IETF Network Slice
Realization of IETF Network Slices is out of scope of this document. Realization of IETF network slices is out of scope of this document.
It is a mapping of the definition of the IETF Network Slice to the It is a mapping of the definition of the IETF network slice to the
underlying infrastructure and is necessarily technology-specific and underlying infrastructure and is necessarily technology-specific and
achieved by the NSC over the SBI. achieved by the NSC over the SBI.
The realization can be achieved in a form of either physical or The realization can be achieved in a form of either physical or
logical connectivity through VPNs (see, for example, logical connectivity through VPNs (see, for example,
[I-D.ietf-teas-enhanced-vpn], a variety of tunneling technologies [I-D.ietf-teas-enhanced-vpn], a variety of tunneling technologies
such as Segment Routing, MPLS, etc. Accordingly, endpoints may be such as Segment Routing, MPLS, etc. Accordingly, endpoints may be
realized as physical or logical service or network functions. realized as physical or logical service or network functions.
9. Isolation in IETF Network Slices 9. Isolation in IETF Network Slices
Editor's note: This content is a work in progress. The section on An IETF network slice consumer may request, that the IETF Network
isolation is too descriptive.
An IETF Network Slice consumer may request, that the IETF Network
Slice delivered to them is isolated from any other network slices of Slice delivered to them is isolated from any other network slices of
services delivered to any other customers. It is expected that the services delivered to any other consumers. It is expected that the
changes to the other network slices of services do not have any changes to the other network slices of services do not have any
negative impact on the delivery of the IETF Network Slice. In a more negative impact on the delivery of the IETF network slice.
general sense, isolation can be classified in the following ways:
Traffic Separation: Traffic of one network slice should not be
subjected to policies and forwarding rules of other network
slices.
Interference Avoidance: Changes in other network slices should not
impact to the SLOs of the network slice. Here the changes in
other network slice may include the changes in connectivity,
traffic volume, traffic pattern, etc.
Service Assurance: In case service degradation is unacceptable due
to unpredictable network situations producing service degradation
(e.g., major congestion events, etc.), explicit reservation of
resources in the network maybe requested for a reduces set IETF
network slices.
9.1. Isolation as a Service Requirement 9.1. Isolation as a Service Requirement
Isolation is an important requirement of IETF network slices for Isolation may be an important requirement of IETF network slices for
services like critical services, emergencies, etc. A consumer may some critical services. A consumer may express this request as an
express this request through the description of SLOs. SLO.
This requirement can be met by simple conformance with other SLOs. This requirement can be met by simple conformance with other SLOs.
For example, traffic congestion (interference from other services) For example, traffic congestion (interference from other services)
might impact on the latency experienced by an IETF network slice. might impact on the latency experienced by an IETF network slice.
Thus, in this example, conformance to a latency SLO would be the Thus, in this example, conformance to a latency SLO would be the
primary requirement for delivery of the IETF network slice service, primary requirement for delivery of the IETF network slice service,
and isolation from other services might be only a means to that end. and isolation from other services might be only a means to that end.
It should be noted that some aspects of isolation may be measurable It should be noted that some aspects of isolation may be measurable
by a customer who have the information about the traffic on a number by a consumer who have the information about the traffic on a number
of IETF network slices or other services. of IETF network slices or other services.
9.2. Isolation in IETF Network Slice Realization 9.2. Isolation in IETF Network Slice Realization
The isolation requirement can be achieved with existing, in- Delivery of isolation is achieved in the realization of IETF network
development, and potential new technologies in IETF. slices, with existing, in-development, and potential new technologies
in IETF. It depends on how a network operator decides to operate
their network and deliver services.
Isolation may be achieved in the underlying network by various forms Isolation may be achieved in the underlying network by various forms
of resource partitioning ranging from dedicated allocation of of resource partitioning ranging from dedicated allocation of
resources for a specific IETF network slice, to sharing or resources resources for a specific IETF network slice, to sharing or resources
with safeguards. For example, traffic separation between different with safeguards. For example, traffic separation between different
IETF network slices may be achieved using VPN technologies, such as IETF network slices may be achieved using VPN technologies, such as
L3VPN, L2VPN, EVPN, etc. Interference avoidance may be achieved by L3VPN, L2VPN, EVPN, etc. Interference avoidance may be achieved by
network capacity planning, allocating dedicated network resources, network capacity planning, allocating dedicated network resources,
traffic policing or shaping, prioritizing in using shared network traffic policing or shaping, prioritizing in using shared network
resources, etc. Finally, service continuity may be ensured by resources, etc. Finally, service continuity may be ensured by
reserving backup paths for critical traffic, dedicating specific reserving backup paths for critical traffic, dedicating specific
network resources for a selected number of network slices, etc. network resources for a selected number of network slices, etc.
9.3. Relationship with Isolation in 5G Network Slice
Editor's note: This 5G subsection should not be added to terminology.
it does not add value to the definitions.
In the context of 5G network slice, "isolation level" is listed as
one of the attributes which can be used to characterize the type of
network slice [GSMA Generic Network Slice Template]. For 5G network
slice, different types of isolation are considered, including
physical and logical isolation. Physical isolation refers to
different physical network entities, and logical isolation is further
classified into virtual resource isolation, network function
isolation and tenant/service isolation.
10. Security Considerations 10. Security Considerations
Editor's Note: Need further improvement; work in progress.
This document specifies terminology and has no direct effect on the This document specifies terminology and has no direct effect on the
security of implementations or deployments. security of implementations or deployments. In this section, a few
of the security aspects are identified.
As noted in Section 4.1.2, some aspects of security may be expressed o Conformance to security constraints: Specific security requests
in SLOs and so form part of the service delivered as an IETF network from consumer defined IETF network slices will be mapped to their
slice. As further mentioned in Section 8, there is an underlying realization in the unerlay networks. It will be required by
asumption that traffic presented to an IETF network slice will not be underlay networks to have capabilities to conform to consumer's
misdelivered to an endpoint that is not part of that IETF network requests as some aspects of security may be expressed in SLOs.
slice.
Furthermore, the nature of conformance to SLOs means that it should o IETF network slice controller authentication: Unerlying networks
not be possible to attack an IETF network slice service by varying need to be protected against the attacks from an adversary NSC as
the traffic on other services or slices carried by the same underlay they can destablize overall network operations. It is
network. This concern can be strengthened by the stipulation of particularly critical since an IETF network slice may span across
"isolation" as an SLO. different networks, therefore, IETF NSC should have strong
authentication with each those networks. Futhermore, both SBI and
NBI need to be secured.
Note, however, that a customer wanting to secure their data and keep o Specific isolation criteria: The nature of conformance to
it private will be responsible for applying appropriate security isolation requests means that it should not be possible to attack
measures to their traffic and not depending on the network operator an IETF network slice service by varying the traffic on other
that provides the IETF network slice. services or slices carried by the same underlay network. In
general, isolation is expected to strengthen the IETF network
slice security.
o Data Integrity of an IETF network slice: A consumer wanting to
secure their data and keep it private will be responsible for
applying appropriate security measures to their traffic and not
depending on the network operator that provides the IETF network
slice. It is expected that for data integrity, a consumer is
responsible for end-to-end encryption of its own traffic.
Note: see NGMN document [NGMN_SEC] on 5G network slice security for
discussion relevant to this section.
11. IANA Considerations 11. IANA Considerations
This memo includes no request to IANA. This memo includes no request to IANA.
12. Acknowledgment 12. Acknowledgment
The entire TEAS NS design team and everyone participating in those The entire TEAS NS design team and everyone participating in those
discussion has contributed to this draft. Particularly, Eric Gray, discussion has contributed to this draft. Particularly, Eric Gray,
Xufeng Liu, Jie Dong, Adrian Farrel, and Jari Arkko for a thorough Xufeng Liu, Jie Dong, Adrian Farrel, and Jari Arkko for a thorough
skipping to change at page 16, line 10 skipping to change at page 15, line 42
Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and
O. Dios, "YANG Data Model for Traffic Engineering (TE) O. Dios, "YANG Data Model for Traffic Engineering (TE)
Topologies", draft-ietf-teas-yang-te-topo-22 (work in Topologies", draft-ietf-teas-yang-te-topo-22 (work in
progress), June 2019. progress), June 2019.
[I-D.nsdt-teas-ns-framework] [I-D.nsdt-teas-ns-framework]
Gray, E. and J. Drake, "Framework for Transport Network Gray, E. and J. Drake, "Framework for Transport Network
Slices", draft-nsdt-teas-ns-framework-02 (work in Slices", draft-nsdt-teas-ns-framework-02 (work in
progress), March 2020. progress), March 2020.
[NGMN_SEC]
NGMN Alliance, "NGMN 5G Security - Network Slicing", April
2016, <https://www.ngmn.org/wp-content/uploads/Publication
s/2016/160429_NGMN_5G_Security_Network_Slicing_v1_0.pdf>.
[PCI] PCI Security Standards Council, "PCI DSS", May 2018, [PCI] PCI Security Standards Council, "PCI DSS", May 2018,
<https://www.pcisecuritystandards.org>. <https://www.pcisecuritystandards.org>.
[RFC2681] Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip [RFC2681] Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip
Delay Metric for IPPM", RFC 2681, DOI 10.17487/RFC2681, Delay Metric for IPPM", RFC 2681, DOI 10.17487/RFC2681,
September 1999, <https://www.rfc-editor.org/info/rfc2681>. September 1999, <https://www.rfc-editor.org/info/rfc2681>.
[RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network [RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network
Address Translator (Traditional NAT)", RFC 3022, Address Translator (Traditional NAT)", RFC 3022,
DOI 10.17487/RFC3022, January 2001, DOI 10.17487/RFC3022, January 2001,
 End of changes. 65 change blocks. 
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