Network Slicing Use Cases: Network Customization and Differentiated Services
draft-netslices-usecases-00
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| Authors | Kiran Makhijani , Jun Qin , Ravi Ravindran , Liang Geng , Li Qiang , Shuping Peng , Xavier de Foy , Akbar Rahman , Alex Galis | ||
| Last updated | 2017-06-02 | ||
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draft-netslices-usecases-00
none K. Makhijani
Internet-Draft J. Qin
Intended status: Informational R. Ravindran
Expires: December 3, 2017 Huawei Technologies
L. Geng
China Mobile
L. Qiang
S. Peng
Huawei Technologies
X. de Foy
A. Rahman
InterDigital Inc.
A. Galis
University College London
June 1, 2017
Network Slicing Use Cases: Network Customization and Differentiated
Services
draft-netslices-usecases-01
Abstract
Network Slicing is meant to enable creating (end-to-end) partitioned
network infrastructure which may include the user equipment, access/
core transport networks, edge and central data center resources to
provide differentiated connectivity behaviors to fulfill the
requirements of distinct services, applications and customers. In
this context, connectivity is not restricted to differentiated
forwarding capabilities but it covers also advanced service functions
that will be invoked when transferring data within a given domain.
The purpose of this document is to focus on use cases that benefit
from the usefulness of network slicing.
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-
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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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 December 3, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://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 Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. A Generalized Network Slice as a Service . . . . . . . . . . 6
3.1. Resource Centric Service Concept . . . . . . . . . . . . 6
3.2. Strict Resource Demand . . . . . . . . . . . . . . . . . 7
3.3. Network Customization . . . . . . . . . . . . . . . . . . 7
3.4. NSaaS of Different Granularities . . . . . . . . . . . . 7
3.5. Challenges in NSaaS . . . . . . . . . . . . . . . . . . . 8
4. Network Slicing in 3GPP Mobile Network . . . . . . . . . . . 8
4.1. Network Slices in 3GPP Systems . . . . . . . . . . . . . 8
4.2. Challenges . . . . . . . . . . . . . . . . . . . . . . . 9
4.3. Creating 3GPP Network Slices . . . . . . . . . . . . . . 9
4.4. Managing 3GPP Network Slices . . . . . . . . . . . . . . 10
4.5. Operating 3GPP Network Slices . . . . . . . . . . . . . . 12
5. Role of NFV in Network slicing . . . . . . . . . . . . . . . 13
5.1. Virtualized Customer Premise Equipment . . . . . . . . . 13
5.1.1. Traditional Customer premise equipments(CPEs) . . . . 13
5.1.2. Trends in CPE infrastructure . . . . . . . . . . . . 14
5.1.3. vCPE as a network slice . . . . . . . . . . . . . . . 15
6. Services with Resource Assurance . . . . . . . . . . . . . . 17
6.1. Enhanced Broadband . . . . . . . . . . . . . . . . . . . 17
6.1.1. Media delivery networks . . . . . . . . . . . . . . . 17
6.1.2. Enhanced Media Streaming Description . . . . . . . . 17
6.1.3. eMBB Type Slices . . . . . . . . . . . . . . . . . . 18
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6.1.4. Required Characteristics . . . . . . . . . . . . . . 19
6.2. Massive machine to machine communication . . . . . . . . 21
6.2.1. Wireless Sensor Networks . . . . . . . . . . . . . . 21
6.2.2. Massive Internet of Things Description . . . . . . . 22
6.2.3. mMTC Type Slices . . . . . . . . . . . . . . . . . . 23
6.2.4. Required Characteristics . . . . . . . . . . . . . . 24
6.3. Ultra-reliable low latency communication . . . . . . . . 24
6.3.1. Brief introduction . . . . . . . . . . . . . . . . . 24
6.3.2. Challenges . . . . . . . . . . . . . . . . . . . . . 24
6.3.3. New service verticals . . . . . . . . . . . . . . . . 24
6.3.4. Required Characteristics . . . . . . . . . . . . . . 26
6.4. Critical Communications . . . . . . . . . . . . . . . . . 28
6.4.1. Public Safety Infrastructure . . . . . . . . . . . . 29
6.4.2. Enhanced Critical Service Type Slices . . . . . . . . 30
7. Network Infrastructure for new technologies . . . . . . . . . 31
7.1. ICN as a Network Slice . . . . . . . . . . . . . . . . . 32
7.1.1. Information Centric Networks Description . . . . . . 32
7.1.2. ICN Type Slices Asks . . . . . . . . . . . . . . . . 33
7.1.3. Required Characteristics . . . . . . . . . . . . . . 33
7.2. Network Slices in Communication Endpoints . . . . . . . . 34
7.2.1. Connected Vehicle . . . . . . . . . . . . . . . . . . 34
7.2.2. Sliced Terminal . . . . . . . . . . . . . . . . . . . 35
7.2.3. Required Characteristics . . . . . . . . . . . . . . 35
8. Overall Use case Analysis . . . . . . . . . . . . . . . . . . 35
8.1. Requirements Reference . . . . . . . . . . . . . . . . . 35
8.2. Mapping Common characteristics to Requirements . . . . . 36
8.2.1. Req.1 Network Slicing Resource Specification . . . . 36
8.2.2. Req.2 Cross-Network Segment & Cross-Domain
Negotiation . . . . . . . . . . . . . . . . . . . . . 36
8.2.3. Req.3 Guaranteed Slice Performance and Isolation . . 37
8.2.4. Req.4 Slice Identification . . . . . . . . . . . . . 37
8.2.5. Req.5 NS Domain-Abstraction . . . . . . . . . . . . . 38
8.2.6. Req.6 OAM Operations with Customized Granularity . . 38
8.3. Mapping Common Characteristics to Requirements . . . . . 38
8.4. Other Challenges and Considerations . . . . . . . . . . . 40
9. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 40
10. Security Considerations . . . . . . . . . . . . . . . . . . . 41
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 41
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 41
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 41
13.1. Normative References . . . . . . . . . . . . . . . . . . 41
13.2. Informative References . . . . . . . . . . . . . . . . . 42
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 44
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1. Introduction
Network Slicing enables the creation of (end-to-end) partitioned
network infrastructure which may include the user equipment, access/
core transport networks, edge and central data center resources to
provide differentiated connectivity behaviors to fulfill the
requirements of distinct services, applications and customers. In
this context, connectivity is not restricted to differentiated
forwarding capabilities but it also spans service, management and
control plane support offered to a slice instance.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119.
1.2. Terminology
Please refer to [ns-architecture] for related terminologies and
definitions.
Additionally, the following terms are used -
o V2X (Vehicle-to-everything): Is a communication of information
from a vehicle to any other entity that may be a another vehicle,
road-side network element or application end point.
o ITS (Intelligent Transportation Systems): Considered as an aspect
of how using Internet of Things resource like road sensors can
creates a smart transport network. The network offers services
related to transport and traffic management systems through flow
of information between road-side sensors, vehicles, smart devices
and humans.
o Over-the-top (OTT): A service, e.g., content delivery using a CDN
or a social networking service, operated by a different service
providers to which the users of the NSP service are attached to,
and to whom it serves as a communication (or bit pipe) provider
o Industry vertical: A collection of services or tools specific to
an industry, trade or market sector. also, referred to as Service
Verticals in this document.
o TETRA: Terrestrial trunked radio is a digital trunked mobile radio
standard to meet needs of public safety, transportation and
utilities like organizations.
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o SLA: Service Level Agreement - A contract between a service
provider and an end user that stipulates a specified level of
service, support option, a guaranteed level of system performance
as relates to downtime or uptime.
2. Scope
To maximize resource utilization and minimize infrastructure cost,
services will need to operate over a shared network infrastructure,
as against the traditional monolithic model operated either as
dedicated network or as an overlay. Service operators can utilize or
benefit from Network Slicing through multi-tenancy, enabling
different customized network infrastructures for different group of
services across different network segments and operating them
independently.
In this document, multi-domain refers to combination of different
kinds of connection-technology network domains. For example, it may
be a RAN, DSL etc in access, mobile core network, Internet Service
Provider (ISP) or different domains in transport networks such as
carrier ethernet, optical, MPLS, TE-tunnel etc. Often, different
technology domains are under the same administrator's control as but
may also require coordination across different administrations.
Although 5G will drive NS based deployments, the document also covers
generalized scenarios that can be applied to existing
infrastructures.
The remaining document is organized as below:
o In Section 3, Network Slice as a Service(NSaaS) delivery model is
described.
o In Section 4, 3GPP architecture for 5G is discussed as a use case
so that any requirements arising from current 5G based
architecture are taken into consideration during slicing
activities in IETF.
o Use cases are discussed from 2 perspectives
a Existing scenarios: Several already deployed or existing
examples that would further benefit when deployed through
Network Slice paradigm are discussed in Section 5.
b Differentiated service scenarios: that must absolutely meet
strict resource requirements, as if they use a dedicated
infrastructure. The example use cases are categorized in
Section 6.
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o End-to-end slicing requires awareness in a terminal to select a
specific or many slices. This is discussed in Section 7.2.
o In Section 8, the use case requirements are summarized and mapped
to the [I-D.qiang-netslices-gap-analysis].
3. A Generalized Network Slice as a Service
Network slicing instances share a common infrastructure, which
provide flexible design of specific network functions, customized to
support differentiated performance requirements of vertical industry,
logical or physical system isolation and certain OAM tools.
Traditionally, vertical industries run their services in a shared
network environment upon which infrastructure owner and service
provider offers standalone network capabilities including
connections, storage and etc. Network slicing shall support the
requirements of a network slicing tenant to be met individually.
Hence it is anticipated that this type of new business model where
network slice instances are leased to industry verticals as a service
(i.e. Network Slcing as a Service, NSaaS) may become a norm in the
near future).
3.1. Resource Centric Service Concept
Network services specify a set of resource requirements to offer
desired Quality of Experience (QoE) to it consumers, using features
offered by the control and forwarding plane Traditional service
guarantees are associated with resource attributes such as
throughput, packet loss, latency, network bandwidth/burst or other
bit rates and security. In addition, redundancy and reliability are
provided by the infrastructure to improve over all QoE. More
recently, newer concepts such as edge computing allows opportunistic
placement of services to meet diverse requirments of low latency and/
or high bandwidth applications.
Clearly the description of service delivery is more diverse than
before and demands higher degree of engineering and agility. The
motivation behind Network slicing paradigm is to enable new service
deployments without having to build new network infrastructures or
causing disruptions to other already deployed services in the
network. In this regard, there are two primary characteristics NS
should satisfy, a) Strict demand for network resource, b) Network
Customization.
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3.2. Strict Resource Demand
Several services are sensitive to response times and/or amount of
bandwidth, e.g. realtime interactive multimedia, high bandwidth video
feed or remote access to an enterprise network. Failure to meet
these criteria leads to service degradation. Moreover, new industry
verticals are evolving due to technological advancements in sensors,
IoT, robotics and multi-media, along with new type of network
interactions (both human-human or human-machine). These impose even
stricter resource and connectivity requirements. The challenge lies
in utilizing common network infrastructure and judiciously allocating
available infrastructure resources.
3.3. Network Customization
Network slicing requires ability to customize. Customization gives
control to the operator of a slice to create, provision and change
network resources to suit their service demands. Customization
enables decomposition of resources from an underlying network
infrastructure and logically aggregate them as part of a slice.
These customizations also include placement and logical connection of
the network functions based on the service requirements.
3.4. NSaaS of Different Granularities
In order to meet various requirements from the network slice tenant,
NSaaS should be be provided with different granularities. Some
typical examples of granularities are as follows.
o Network Segments - Network slice instances of different network
segment, i.e. radio access network, transport network and core
network.
o SLA requirements - Network slice instances of different SLA
requirements, i.e. low-latency network, legacy best-effort network
and network with guaranteed-bandwidth.
o Vertical applications - Network slice instances of different
industry verticals. i.e. manufacturing site, V2X, industrial IoT
and smart city.
o Access technologies - Network slice instances of different
generations of cellular and fixed network technologies, i.e. 4G,
enhanced Mobile Broadband(eMBB), Ultra-Reliable and Low Latency
Communication(URLLC), WiFi, Passive Optical Network (PON) and DSL.
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o OTT services - Network slice instances of different applications
provided by OTT, i.e. messaging, payment, video streaming and
gaming.
During the realization of network slicing, it is also very important
that sub-instance of a more general one can be provided with a finer
granularity. In practice, it is up to the provider to decide the
granularity to lease the network slice instances.
Editor's note: please revisit definitions for consistency.
3.5. Challenges in NSaaS
The flexibility and customization of different network slicing
granularity introduce many challenges, especially in terms of network
management and orchestration. As a network slice provider (provider
of end-to-end slice orchestration), it is essential to have a
comprehensive understanding of the network capability. This requires
that network connectivity and resources can be exposed to the network
slice tenants - the differentiated services offerers. Accordingly,
network slice provider is able to orchestrate specific instances
based on these exposed capabilities.
4. Network Slicing in 3GPP Mobile Network
Network Slicing is a core feature of the currently under development
3GPP 5G phase 1 mobile system, because it makes it possible for
different vertical applications, such as IoT and broadband
applications, to be deployed over a common infrastructure. More
details can be found in [TS_3GPP.23.501], [TS_3GPP.23.502],
[TR_3GPP.38.801], [TR_3GPP.33.899] and [TS_3GPP.28.500].
4.1. Network Slices in 3GPP Systems
In 3GPP systems a network slice is a complete logical network which
provides telecommunication services and network capabilities.
Distinct Radio Access Network (RAN) network slices and core network
slices will interwork with each other to provide mobile connectivity.
A device may access multiple network slices simultaneously through a
single RAN.
3GPP defines slice IDs (named (S-)NSSAI in the standard) composed of
a Slice Service Type (SST) and optionally a Slice Differentiator
(SD). SST refers to an expected network behavior in terms of
features and services (e.g. specialized for broadband or massive
IoT), while SD helps distinguishing among several network slice
instances.
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Figure 1 describes the general layout of Network Slicing in mobile
networks. A core network slice is composed, on the control plane
side, of a Session Management Function (SMF), which manages PDU
sessions, and, on the user plane side, of a User Plane Function (UPF)
and possibly other functions. It is interconnected with a RAN Slice
to complete the user plane. Some functions on the control plane are
common and shared between multiple RAN and core network slices. A
primary example of such a shared function is the Access and Mobility
management Function (AMF).
Common Functions Core Network Slice Instance
+-----------------+---------------------+
| +--------+ | +--------+ |
| | Control| | | Control| |
+--------+ Plane +----------+ Plane | |
| | | AMF... | | | SMF... | |
+---+--+ | +--------+ | +----+---+ |
|Device| +-----------------+ | |
+---+--+ | +--------+ | +------+-----+ |
| | | | | | User Plane | | +---------------+
+--------+ RAN +--------+ Functions +------+Data Network or|
| | | | | UPF... | | | The Internet |
| +--------+ | +------------+ | +---------------+
+-----------------+---------------------+
RAN Slice Instance
Figure 1: 3GPP Network Slices
4.2. Challenges
A core challenge here is to identify or develop a set of technologies
suitable to implement the infrastructure over which 3GPP Network
Slicing will be built, without requiring major rework of the 3GPP
specifications. Among the specific challenges that an IETF NS
framework will need to address, it will need to support sharing
network functions between several slices, building slices recursively
from smaller slices, implementing roaming across different domains,
etc. The following subsections describe creation, management and
operation of 3GPP network slices as currently planned in the
specifications, in order to better understand those challenges.
4.3. Creating 3GPP Network Slices
To create a network slice instance, mobile network operators will
start by describing it by assembling together "Network Slice
Subnets", which are smaller components included in a RAN or core
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network slice. Network slice subnets include NFs and reserved
network resources, in term of KPIs such as minimum and maximum
throughput, delay, packet loss, etc. Network slice subnets can be
shared between several network slices. Both network slices and their
subnets are described by the operator through the OSS/BSS management
system. The OSS/BSS translates this input from the operator into
descriptors that are sent to an orchestrator. The orchestrator,
through the rest of the NFV-MANO system, configures compute and
network elements to create network slice subnets and compose them as
a network slice. Beyond creation, RAN or core network slice
activation is orchestrated as the activation of individual subnets,
possibly in a given order.
Network slices are isolated from each other to avoid control plane
congestion on one slice (e.g. using one SMF in slice dedicated for
broadband applications) to affect the control plane of other slices
(e.g. to affect potentially critical IoT applications). Since some
common core network functions (AMF, PCF, UDM, etc.) are shared
between multiple dedicated core network slices, the interaction
between shared NFs and NFs in dedicated network slices should be
isolated from each other as well.
Network slices creation will support different combinations of "n"
network services, "m" client devices and "p" interconnections with
external (sliced or non-sliced) networks and services. In 3GPP, RAN
and core network slices are typically dedicated to a certain type of
network services such as broadband or IoT, but may serve one or more
network services of this type. Additionally, in some mobile
networks, parts of the core network may not be implemented over a
slice, while others are (e.g. SMF could be in a slice, while common
functions are not). While this can lead to a sub-optimal isolation
between slices, this effect can be partially compensated by over-
provisioning non-sliced sections of the network.
4.4. Managing 3GPP Network Slices
Mobile network operators can modify the configuration of a RAN or
core network slices, while it is in use. Example of such operations
include:
o Increase or decrease compute capacity of NFs
o Increase or decrease network capacity
o Update the configuration of NFs
o Add, replace or remove a NFs
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o Add, replace or remove a Network Slice Subnet
Some operations affecting a shared slice may not be possible without
affecting other network slices, and in this case may be replaced by
other operations: for example, instead of changing the configuration
of a shared AMF to accommodate the needs of a SMF, another network
slice subnet with an AMF may be created, and replace the original
AMF's slice for this SMF. The management system monitors performance
of individual network slice components and coalesce performance data
and events for the whole RAN or core network slice. This includes
user and control traffic load data, QoS/SLA data, e.g. indicating
whether services were provided at expected QoS/SLA level. The
management system uses this information for example to decide to
scale up or down NFs. Performance data and events from a shared
network slice component will be attributed by the 3GPP management
system to one of the RAN or core network slices that contain or
interact with this shared component. To support roaming, mobile
network operators will need to configure the interconnection between
network slices on the home network and network slices on the visited
network. On the visited side, the operator ensures that the proper
network slice is selected for a roaming device. User traffic will
flow through the visited network slice either directly to an external
data network, or through the interconnected home network slice (both
cases will need to be supported). From the end user perspective only
the performance of the whole (visited + home) network slice is
important. Mobile network operators may expose limited 3GPP network
slice management to third party communication service providers
(CSP), who may in turn consume this service or provide it to their
own customers, as a form of "Slice as a Service" described
in Section 3. Using this interface, a CSP can request the creation
of a network slice using specifications of NFs, isolation, security,
performance requirements (such as traffic demand requirements for the
coverage areas, QoS for service). When an operator exposes
management data (e.g. fault management data, performance data) about
a network slice shared by multiple customers of a CSP, exposed
management data of each customer can be isolated from each other.
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+--------+
Limited NS | |
Limited NS Instance |Customer|
+-------+ Instance +-------------+ Management | |
|Mobile | Management |Communication+<-----------+--------+
|Network+<------------+Service |
| | |Provider +<-----------+--------+
+-------+ +-------------+ Limited NS | |
Instance |Customer|
Management | |
+--------+
Figure 2: 3GPP Limited Network Slice Management Exposure
4.5. Operating 3GPP Network Slices
Slice selection occurs in 2 phases: first, when initially registering
with the network, the device lists the slice IDs it wishes support
for. This list could be part of the configuration of the device.
The network uses it, among other information like device
capabilities, subscription information and local operator policies,
to pre-select one or more RAN slices and core network slices. In
this process, a set of 5G Common Control Plane Functions (CCNF) are
selected to process future requests from the device. No resource
reservation occurs at this stage. Later on, a particular application
is started on the device. Using a slice ID associated with the
application, the device requests from the network the establishment
of flows for this application. For example, this slice ID can be
associated to the application by the application service provider.
This slice ID is used by the network to select the actual RAN slice
and core network slice that will host user and control plane flows
and network functions. In the user plane, network resource
reservation (in term of KPIs such as maximum throughput, delay, etc.)
is applied at the individual application flow level (e.g. at the PDU
Session level in 3GPP terms). In the control plane, resource
reservation can be performed in a less granular fashion, e.g.
reservation may occur once for a given slice. During the lifetime of
a device connection to a network, application flows will be
established and maintained through a given set of common control
plane function (CCNF), which may rarely change. In general, a single
device and a single CCNF will therefore interoperate with multiple
slices simultaneously (e.g. a broadband and a Tactile Internet
slice).
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+-------+
RAN uses Slide IDs |Device |
to select CCNF +---+---+
\ |(Slide IDs, a.k.a. NSSAI)
+---+---+
CCNF uses Slide IDs | RAN +-------------+
to select slices +---+---+---------+ |
\ |(Slide IDs ) | |
+-------+--------+ | |
| Common Control | | |
| Plane Network | | |
| Functions | | |
| (CCNF) | | |
+-----+----+-----+ | |
| | | |
+---------|----+----------|---+-------+
+------------|---------------|-------+ |
| +---------++ +-----+----+ | |
| | +------+ | | +------+ | | |
| | |CP NF1| | | |UP NF1| | | |
| | +------+ | | +------+ | | |
| | ... | | ... | | |
| | +------+ | | +------+ | | |
| | |CP NFn| | | |UP NFn| | | |
| | +------+ | | +------+ | +---+
| +----------+ +----------+ |
+------------------------------------+
Core Network Slice Instances
Figure 3: 3GPP Network Slice Selection
5. Role of NFV in Network slicing
Virtualization is a key enabler of network slices; Many network
services can be easily deployed using components of NFV framework
like network functions, hardware decoupling and resource placement
[#?NFVSLICE]. When deployed as a network slice, the resources
associated with virtualized network services are managed uniformly by
infrastructure provider. One such use case is described below.
5.1. Virtualized Customer Premise Equipment
5.1.1. Traditional Customer premise equipments(CPEs)
A CPE is an equipment that connects the customer premises to the
provider's network. A CPE may either be a layer-2 or a layer-3
device (the routing gateway) performing different network functions
depending on the access technology (DSL modem, PON modem, etc.). Any
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services provided such as Internet access, IPTV, VoIP, etc. or
network functions for example, local NAT, local DHCP, IGMP proxy-
routing, PPP sessions, routing, etc. are also part of CPE. The
installation of different on premise devices, entails a high cost for
service providers in terms of both initial installation and
operational support, since they are typically responsible for the
end-to-end service.
+-----+ campus
|----| CPEx | -----[ ]
| +-----+
----- Broadband | +-----+ branch
( ) ----------------|--->| CPEy |------[ ]
( CSP ) MPLS | +-----+
(____) access| +------+ main site
|--->| CPEz |----- [ ]
+------+
Figure 4: Traditional CPE architecture
Traditional CPE deployments are shown in figure Figure 4. These are
service provider network functions installed on customer site to
provide above mentioned functionalities along with remote site
connectivity. Communication Service provider (CSP) is responsible
for management and administration of connections and state with
proper policy, bandwidth, security and QoS requirements.
5.1.2. Trends in CPE infrastructure
A virtualized CPE architecture moves several network functions from
on premise to the service provider network to facilitate provisioning
of new services to customers based on a lean CPE functions on
premises such as minimizing number of network functions on customer
premises, perhaps only layer-2 visibility among them with no need for
routing gateways in the home network is suppressed. Several routing,
NAT, firewall capabilities may be performed in the service provider's
cloud. A customer's site is highly simplified with vCPE solution,
perhaps requiring only access level connectivity on premise and
moving other network functions to ISP's cloud.
A vCPE when combined with SD-WAN technology provides service
guarantees for different enterprise applications and with a
generalized sliced approach, the solution can be customized on per
enterprise basis using a standard approach to delivery of WAN
solutions to multiple enterprises.
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|-----------------------|
| +------+ |------------------+-------+ campus
| |--| | | | vCPEx | -----[ ]
| | | | |------------------+-------+
| | | | | <====Broadband ==>
| ----- | | vCPE | | -----------------+-------+ branch
| ( ) |->| | | | vCPEy |------[ ]
| ( CSP )| | | |------------------+-------+
| (_____) | | | |<=== MPLS/4G. ==>
| | | | |------------------+-------+ main site
| |->| | | | vCPEz |----- [ ]
| +------+ |------------------+-------+
|-----------------------|
Figure 5: irtualized CPE, with distributed architecture
Figure 5 shows a virtualized architecture in which many functions are
moved to CSP's cloud simplifying CPE on premises tremendously.
Additional details of deployment architecture models are captured in
[I-D.pularikkal-virtual-cpe] where full dissemination of data path
and control plane functions is described. Here only a high-level
relevance of virtualized CPE is shown. The figure shows vCPEx,
vCPEy, vCPEz are virtualized CPEs on multiple sites of a specific
customer, there may be set of different network functions in each x,
y and z CPE. The vCPE instance in CSP cloud is integrated to each
site performing service chains of network functions and resource
allocations specific for ingress and egress path of each site.
5.1.2.1. Challenges
A vCPE is a well-known concept[VCPEBBF] which when combined with WAN
technologies provides end to end visibility and reachability to
remote sites. It has been solved using network function
virtualization (NFV) approaches and via offload of compute intensive
functions to the CSP cloud for ease of management by CSP. However,
there is no standard approach to connectivity or management of
various CPE functions. Furthermore, it is highly desirable for
customers to control and monitor their own network resources at both
remote and local sites. Using network slicing, a greater level of
agility can be achieved, with each customer dynamically managing its
own network with the assistance of network slicing framework.
5.1.3. vCPE as a network slice
The benefit of self-managing a vCPE network slice is the capability
to move network functions on premise of to the cloud. An obvious use
case will be customer initiated gradual migration of network
functions from a site to CSP cloud.
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+-------------+ +-------------+
| E2E Slice | | Slice |
| Orchestrator| | Resource Mgr|
+-------------+ +-------------+
| ^
| NS protocol or i/f |
V V
|--------------------------------------------------|
| |
| +-------------+ +-------------+ |
| | vCPE Slice | | CSP | |
| | Mgr/Monitor | | vCPE subnet | |
| +-------------+ +-------------+ |
| |
| +--------+ +--------+ +--------+ +--------+ |
| | vCPEy | | vCPEy | | trans | | vCPEz | |
| | subnet | | subnet | | subnet | | subnet | |
| +--------+ +--------+ +--------+ +--------+ |
| |
|--------------------------------------------------|
| |
| NS transport protocol or i/f |
V V
[Campus] [branch] [Transport] [main site]
Figure 6: vCPE as a Network Slice
Editor's Note: TODO: here we have inconsistencies between the drafts
and more importantly with the 3GPPP and TM forum.
In Figure 6, a slice for vCPE is shown. Using slice subnet approach,
each vCPE site instance may be considered as a subnet, along with the
WAN transport as another subnet. The network functions are chained
in a distributed fashion between site vCPEs and CSP vCPE subnet. A
monitoring function interfaces with CSP's global slice manager for
resource management and an interface to physical infrastructure
through network slice transport protocol, realizes these functions on
the infrastructure.
5.1.3.1. Required Characteristics
Having a dedicated sliced network catering to dynamic customization
of network functions with guaranteed resource method, simplifies
network operations. In case of such vCPE type solutions, it is
common for each customer to have its own private IP address space,
therefore, the resource isolation must include address isolations as
well. This may be achieved based on existing label techniques or
through new network slicing data path protocol.
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6. Services with Resource Assurance
6.1. Enhanced Broadband
Today, video consumes the largest amount of bandwidth over the
Internet. As the higher resolution formats enter mainstream, even
more bandwidth will be needed to stream 4K/8K/360 degree formats.
The scenario in this section are discussed in regards to need for
demands beyond best-effort network delivery, in particular
requirements due to growth in data rate capacity, connection density
and interactive media. These are equally applicable to both fixed
and mobile networks.
6.1.1. Media delivery networks
+-----+
|=>| DASH|
| +-----+
+------------+ +-------------+ ----- +-----+ | +-----+
| Content |<==>| Transcoding |<=> ( ) ==>| CDN |=|=>| HDS |
| Aquisition | | Function | ( ISP ) +-----+ | +-----+
+------------+ +-------------+ (____) | +-----+
|=>| HLS |
+-----+
Media delivery formats
Figure 7: Traditional Streaming Media Infrastructure
6.1.2. Enhanced Media Streaming Description
Today the video output format is HD with 1080p resolution with few
services delivering up to 4K. Both Video-on-demand and live-linear
channels (streaming live event feed) can be supported. Most often
media services are delivered using streaming platforms.
6.1.2.1. Factors Influencing Enhanced Broadband Use Cases
Media delivery comprises of different functional components, as shown
in Figure 7 above and often an overlay or OTT infrastructure is used.
The deployment requires acquiring content, transcoders and CDN
servers and decoders to support different delivery formats All these
may be considered specialized service functions in media streaming
infrastructure. The entire operation is (a) not flexible in terms of
resources placement (on premise vs cloud vs proximity to destination)
(b) is built on best-effort of available resources, (c) Is reactive
when the congestion occurs leading to client-server based end to end
stream optimization derived from network conditions.
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6.1.2.2. Traditional Media Streaming Service Verticals
There are 3 categories of media or content distribution
a Video on Demand (VOD)
b Live streaming/Linear channels
c Video conferencing
While a and b are one way content consumption, Video conferencing
requires 2-way or multi-way connection. It may consist of either
person-person or person-group video communication.
6.1.2.3. New Verticals - Virtual Reality (VR)/Augmented Reality (AR)
Virtual Reality(VR)/Augmented Reality(AR) is the future use case of
eMBB services. A 360-degree video is mostly low resolution,
requiring ~25 Mbps network bandwidth for streaming. For a network
based AR/VR bandwidth required will be in the order of Gbps and
latency less than 10 milliseconds for a fully immersive experience
such as cloud-based VR gaming, fully-interactive media experience.
However, media processing for AR/VR will still be identical to in-
network processing functions as shown in figure 1 and corresponding
latencies could lead to downgrade of user experience. Therefore,
upon request for an AR/VR stream a special infrastructure is required
that differs from best-effort network.
6.1.3. eMBB Type Slices
A purpose-built network slice for eMBB streaming shall ensure to
minimize processing overheads, it may be done by placement of network
functions closer to subscribers.
o Resource scaling: eMBB resources should be allocated dynamically
because bandwidth is expensive and requirements are high, such
vertical service operators may not want to pay for unutilized
bandwidth. Therefore, slices should adjust in negotiated chunks
of scale both bandwidth and service functions. For example, if a
stream is viewed by 8 people initially, the resource for 20 users
is allocated. It will subsequently grow or shrink in chunks of
resource for 20 subscribers.
o Transport resource constraints are different for the Fan-out
network between user and distribution network; and content
acquisition to distribution network.
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o Latency Guarantee varies for live streaming, on-demand streaming
and connected AR/VR streaming
+----------------------------------+
| E2E Slice Orchestrator |
| |
| +------------------+ |
| | eMBB Resource | |
| +--> | Spec Guard |---+ |
| | +------------------+ | |
| | | |
| | +----------+-------+ | |
| +--->| Resource Monitor|<--+ |
| +---------+--------+ |
| ^ | |
|-----------+-------------+--------+
| |
| Real time feed|back
| |
eMBB | |
Network | v dynamic resource adjustment
+------------+------------+-------------+
| +----------+-------+ +-----------+ |
| | Acquired Content|<-->| eMBB slice| |
| | subnet | | Customizer| |
| +---------+--------+ +-----------+ |
| | | | +-+
| | | =======> | |
| +--------+ +-------+ | | +-+ handheld
| | CDN1 | | CDN2 | | | +---+
| | subnet | | subnet| ========>| |
| +--------+ +-------+ | | +---+ PC
| | | | |
| +-----------------+ | | +---------+
| | Encoders subnet |================+=+====>| |
| +-----------------+ | +---------+ TV
+----+----------+---------+-------+-----+
Figure 8: Reference eMBB slice
See Figure 8 above for a reference slice.
6.1.4. Required Characteristics
A typical eMBB slice flow from a network operator is as follows
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o There is an eMBB slice offering template/form. A service vertical
provider requests
1. Regional network locations of CDN and location of acquired
content.
2. Describes transport requirements for its own distribution
network comprising of connectivity between content acquisition
and Fan-out points.
3. A granularity of transport resource chunk.
4. It may request access to subscriber database from multiple
access network types (mobile, fixed) creating value add for
both service provider.
5. For each access type resource requirement is specified.
o Registers self with access rights to resource monitoring and
negotiation loop. Slice operator has an abstracted view of its
own slice instance topology.
o Network operator has end to end (acquired content to cached
content to user) visibility across different domain segments and
corresponding transport resources. A well-coordinated network
slice protocol enables resource allocation across different
segments.
Note in addition to eMBB, traditional CDN use cases can be deployed
in a slice as well, see examples in [RFC6770].
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+-------------------------------------------------------------+
| +-----------------------+ |
| +-------->| E2E Slice Orchestrator|<----+ |
| | +-----------------------+ | |
| | | |
| +------+-----------+ +-----------+-------+ |
| | Global | | eMBB Slice | |
| | Resource Manager |<------------> | Resource Allocator| |
| +------------------+ +-------------------+ |
| |
+-------------------------------------------------------------+
| |
------- NS control -------------- NS control--
| |
------------------ -----------------
| -------------- | | -------------- |
| | eMBB Manager | | | | eMBB Manager ||
| -------------- | | -------------- |
| | | |
| | | |
| -------------- | | -------------- |
| | eMBB Network | | | | eMBB Network ||
| |-------------- | | -------------- |
-------------------- -----------------
| | | |
V V V V
------------------NS transport ----------------
| | |
V V V
---------------- ---------------- -----------
| Infrastructure | |Infrastructure | | DC |
| Domain A | | Domain B | | Domain C |
---------------- ---------------- -----------
Figure 9: Transport provider network operator view. shows deployed
eMBB slice components for reference.
6.2. Massive machine to machine communication
6.2.1. Wireless Sensor Networks
Sensor networks are widely deployed in industries such as
agriculture, environmental monitoring and manufacturing. The general
workflow of wireless sensor network is provided in Figure 10.
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6.Decided Behavior
+-------------------+
| |
+----v------+ |
| Sensor | |
|(1. Data | |
|Collection)| |
+----+------+ |
|2.Collected Data | 3.Aggregated +---------------------+
+------------->+----------+ Data | Data Center |
| Sink Node/ |----------> (4. Data Analysis |
| Base Station| | & |
+---------->+--------------+--<------| Behavior Decision) |
|2.Collected Data | 5. Decided +---------------------+
+----+------+ | Behavior
| Sensor | |
|(1. Data | |
|Collection)| |
+----^------+ |
| |
+-------------------+
6.Decided Behavior
Figure 10: Workflow of wireless sensor network
As figure Figure 10 shows, sensors mainly collect data & behavior;
rarely communicate with each other in traditional wireless sensor
network. While in the scenarios discussed in this section, sensors
or embedded devices will be more intelligent and carry out more
frequent interactions that raises more challenges for mobile
networks.
6.2.2. Massive Internet of Things Description
Machine-to-machine type communication will dominate communication
paradigm in various industries such as healthcare, manufacturing,
transportation, etc. In order to support the massive internet of
things, traditional mobile networks have to be redefined -- by
creating the connectivity fabric for everything and bringing new
levels of on-device intelligence.
6.2.2.1. Factors Influencing Massive Internet of Things Use Cases
There are three main challenges raised by Massive Internet of Things
use cases:
o Scalable connectivity: there will be billions of smart devices
connect to mobile networks worldwide by 2020;
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o Wide area coverage: sensor could be embedded into various
household equipments, medical instruments, vehicles, or even
public facilities;
o Frequent small amount data transmission: due to limited power,
most of the embedded sensors work intermittently rather than
continuously.
6.2.2.2. New Massive Machine Type Communications (mMTC) Verticals
A few examples of new types of scenarios that require unique
infrastructure are mentioned below.
6.2.2.2.1. Smart City
Smart city networks is an integration of several public
infrastructures together through M2M communications. For example
o Automatic metering for gas, energy, water, etc;
o Environment monitoring for pollution, temperature, humidity, etc;
o Light management inside buildings or even the whole city;
o Traffic signal control;
o Public safety alerting for natural disaster.
Building a smart city requires a variety of IoT networks to inter-
operate together; these IoT networks are run by different departments
with different access privileges for administration and access
control. A smart-city network should be isolated from the public
Internet.
6.2.2.2.2. E-Health
E-health refers to the application that remote monitor the physical
conditions (e.g., heart rate, pulse, blood pressure etc.), and
accordingly take necessary medical measures remotely. Being a life-
critical service, e-health communication network must be reliable and
fast but small-size of data exchange. In addition, the privacy and
security of user's data must be guaranteed.
6.2.3. mMTC Type Slices
mMTC involves potentially a large number of small and power-
constrained devices, therefore, resource allocation at scale is of
particular importance in mMTC type slices. Furthermore, different
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kind of IoT devices may exhibit quite different traffic patterns
e.g., continuous (heart rate monitors) & periodic delay tolerant
(temperature sensors), delay sensitive (e.g., weather forecast &
disaster alerting), mobility mode, security awareness etc. The mMTC
type slices should be conscious of various requirements of scale,
data pattern, reliability, security and energy efficient
communications.
6.2.4. Required Characteristics
Different from eMBB and uRLLC type services, mMTC service does not
have so much strict requirements on bandwidth and latency. Massive
and ubiquitous connectivity support would become the biggest
challenge of mMTC service. That is, for an network operator, mMTC is
mainly concentrated in the access network side and most of the
information flow should not pass through the transmission or core
network, both for security and communication efficiency. The
mobility management IoT gateway functions could be placed closer to
terminals (e.g., base-stations, edge clouds, etc.). Consequently, an
mMTC type slice should consist of plentiful access network resource,
as well as normal yet reliable transmission network and core network
resources in general.
6.3. Ultra-reliable low latency communication
6.3.1. Brief introduction
Not only, mission critical communication services but industrial
manufacturing, production processes, remote medical surgery, and
transportation safety (high mobility cases), etc scenarios require
ultra-reliable communications with no packet loss.
6.3.2. Challenges
In uRLLC scenarios, both data and control planes may require
significant enhancements to transmission or information distribution
protocols. [TR_3GPP_38.913] specifies generic KPIs for access
network user plane latency as 1ms and reliability factor of 99.999%
for transmission of a packet of size 32 bytes. Although KPIs vary
for different scenarios such as V2X(3-10ms, 99.999%), eMBB (4ms UL/DL
each), In order to meet these, latency and reliability of the
transport in mobile networks should also be considered.
6.3.3. New service verticals
In the following sections three new uRLLC scenarios are described.
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6.3.3.1. Industrial Operation and Inspection
Operations in remote industry sites usually need the support of
mobile transport network. Accurately operating machinery (low
latency and jitter) from remote locations requires high-quality
communication links between the control site. Factors to consider *
low latency and low jtter in communication path * Short time interval
between an operator sending control signal tp equipment response.
In an industrial closed control loop (Sensor -Controller - Actuator)
as shown in figure Figure 11, a typical control cycle time where
network is involved should be below 10ms [White-paper-5GAA].
++++++++++ +++++++++++++++
+ Sensor +-->+ Transmitter +---+
++++++++++ +++++++++++++++ |
| ++++++++++++ ++++++++++++++
+-->+ Base +---->+ Controller +
+---+ Station +<----+ +
| ++++++++++++ ++++++++++++++
++++++++++ +++++++++++++++ |
+Actuator+<--+ Receiver +<--+
++++++++++ +++++++++++++++
Figure 11: Industrial closed control loop
6.3.3.2. Remote Surgery
Remote surgery which enables surgeons to perform critical specialized
medical procedures remotely, allowing their vital expertise to be
applied globally. Providing accurate control and feedback for the
surgeon entails very strict requirements in terms of latency,
reliability and security.
6.3.3.3. Vehicle-To-Everything (V2X)
Vehicle-To-Everything (V2X) network uses precise knowledge of the
traffic situation across the entire road/highway network to optimize
traffic flows, reduce congestion, and minimize accidents. For uRLLC
scenario,
o V2X in access network uses Vehicular Ad Hoc Network (VANET) type
protocols for vehicle-to-vehicle and an access medium
communication (either ITS-band or commercial-cellular). The
topologies are dynamic and mobility is high. In order to support
fully autonomous reliable driving, a highly reliable communication
channel is required.
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o Often, V2X may involve a part transport and core networks for
functions such as subscriber/vehicle admission and intensive
computational resource for aggregating information from multiple
traffic zones.
6.3.4. Required Characteristics
A uRLLC network slice only accepts service specifc traffic and
discards any other type of traffic to avoid negative impact on uRLLC
service operation. Even within the same vertical different kind of
services should be isolated. For example, in the V2X vertical, the
network slice used for autonomous driving should not be used for in-
vehicle infotainment. Capabilities required by uRLLC service
provider include
o Locations of the access nodes for terminals (devices, vehicles) to
the transport network and locations of the controller to construct
its own network topology within the network slice. In high
mobility scenario such as automotive verticals, the dynamic
topology adjustments are required without loss of data.
o Each service vertical has different performance requirements in
terms of latency, reliability and data rate etc., therefore, the
uRLLC network slice should allow customization for these
parameters.
o A uRLLC service provider should be able to registers self with
access rights to resource monitoring and negotiation loop.
From a network operator provides a uRLLC Slice with following
considerations
o Should support/provide specific data and control planes protocols
with significant enhancements for deterministic latency and
reliability (e.g. DetNet[I-D.dt-detnet-dp-sol] in data plane).
o Allow uRLLC provider to access user admission and authentication
to its network slice in advance.
o The network coverage for a uRLLC service provisioning may be
limited to a confined area, either indoor or outdoor, network
operator needs to be able to coordinate resource allocation across
different access types and network segments.
The Figure 12, shows provider and operator view of the network. The
monitoring of resources is done in the context of performance. A
performance degradation would require resource adjustment. As shown
in Figure 12, in one possible sliced model will have its own
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customizer that uses internal performance observing logic with in its
slice by coordinating with different subnets/domains using southbound
NS transport protocol and transfers this information to operator via
a northbound NS protocol for resource adjustment.
It is implied that domains maybe different access technologies and
need for a common performance metric propagation and resource
allocation is important for a uRLLC slice to function properly.
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+-----------------------------+
| E2E Slice Orchestrator |
| |
| +---------+ +-----+ | uRLLC service +---------+
| | Resource| | Perf| <-|---------------| uRLLC |
| +--- | view | | Spec| | template | service |
| | +---------+ +-----+ | +---------+
| | +----------+--------+ |
| +--->|Performance Monitor| |
| +---------+------^--+ |
| | | |
|------------------------|-+--+
| | resource adjustment
| |
performance metrics| |
| |
uRLLC slice | v
+---------+-------------+-------------+
| +--------+--+ +-----------+ |
| | Subs |<-->|uRLLC slice| |
| | Mgmt | |Customizer | |
| +-------+---+ +---------^-+ |
| +-------+------------| |
| | | +---v-----+ +
| +--------+ +-------+ | micro | |
| | GC-1 | | GC-2 | | resource| |
| | subnet | | subnet| | mgr | |
| +--------+ +-------+ +---------+ |
| | | |
+----+----------+---------+-------+---+
| | | |
V V V V
------------NS transport --------------
| | |
V V V
+--------------+ +------------+ +----------+
| Domain A | | Domain B | | Domain C |
+--------------+ +------------+ +----------+
Figure 12: Reference for uRLLC Network Slice.
6.4. Critical Communications
Critical communications are used during emergency situations. Often
referred to as mission critical, the communication has to be reliable
and non-disruptive. Different scenarios of critical communications
relate to public safety responders, military, utility or commercial
applications, mainly using reliable voice or short data messaging
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over wireless communication systems. First responders such as
firefighters, paramedics and other responders, for their daily and
emergency communications needs to be able to communicate without
disruption.
6.4.1. Public Safety Infrastructure
6.4.1.1. Current Improvements over traditional services
Traditional technologies for emergency communications are narrow band
radio networks such as Land Mobile Radio (LMR) systems. They are
terrestrially-based professional push to talk wireless communications
systems commonly used for critical communications by public safety
organizations such as police, firefighters, and other emergency
response organization. LMR and related systems such as TETRA or P25
have dedicated frequencies and channels assigned to individual groups
of users for instant connection through a simple interface. Next-
generation public safety communications are planned to be built with
enhanced broadband voice, data and video communications services
beyond narrowband LMR with broadband LTE networks for high speed data
(ref 22.179 and FirstNet).
6.4.1.2. Challenges for Enhanced Critical communication
3GPP defined on-network critical communication can be established
with the help of a network infrastructure to manage the call. It can
also be off-network, where the terminals communicate directly to each
other. The scope here does not discuss point to point off-network
communication as it is not relevant to the topic.
Most important challenges for on-network communications include:
o Expensive to deploy a separate broadband network: The coverage of
a separate network at the scale of area, state or nationwide that
is interoperable is not cost effective, especially as new
communication technologies emerge, public safety systems should be
able to adapt easily to state of the art.
o Lack of flexibility: in terms of adding new value added services
or ability to take advantage of commercial services.
o Ability to reliable support of basic mission critical services
such as voice: loss of information in voice communication is no
acceptable in emergency services, if common infrastructure is to
be used, it must assure no loss of information.
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6.4.2. Enhanced Critical Service Type Slices
The traditional critical communications use dedicated separate
infrastructures in order to be reliable and non-disruptive. In
contrast, LTE based mechanisms acquire different bearer QoS Class
Identifier (QCI) for different type of barriers (data, voice, video).
The eMC (enhanced mission critical) network slices benefit from the
following:
o Insertion and authorization of subscribers in a group
communication: In a critical infrastructure, the subscriber
authentication may be done earlier at the entry point
automatically through slice selection functional entity.
o Pre-allocated QCIs: Generally, QCIs are requested on per session
basis which could slow down overall call control setup and is
undesirable for emergency services. When operating in a slice,
these resources maybe reserved ahead of time in a coarse-grained
manner instead of per session.
MC Network slices are relatively straight forward as it only concerns
with guaranteed bit rate (GBR) on per media basis and management of
groups. The MC network slice need an ability to request transport
services based on GBR for reliable communication. A reference
network slice below shows a mission critical (MC) organization
providing service agreement through a network slice template with
resource specification. The eMC slice sets up different subnetworks
of different subscriber groups and manages its membership. These
subnets are realized into the infrastructure across different domains
through a network slice transport mechanism. The MC network slice
must be capable of active resource monitoring to prevent congestions
to ever occur as well as request additional transport resources in
case of emergency event occurrence.
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+----------------------------------+
| E2E Slice Orchestrator |
| |
| +------------------+ | service +------------------+
| | eMBB Resource | |<-----------| Mission Critical |
| +--> | Spec Guard |---+ | agreement | Organization |
| | +------------------+ | | +------------------+
| | | |
| | +----------+-------+ | |
| +--->| Resource Monitor|<--+ |
| +---------+--------+ |
| ^ | |
|-----------+-------------+--------+
| |
| Resource request
| | prioritized resource adjustment
MC Network|Slice v dynamic group management
+------------+------------+-------------+
| +----------+-------+ +-----------+ |
| | Group Subs Mgmt |<-->| MC slice | |
| | | | Customizer| |
| +---------+--------+ +-----------+ |
| | | | +-+
| | | +---------+ + +-->| |
| +--------+ +-------+ | GRP | | +-+ MC-UE
| | GC-1 | | GC-2 | | selector| | +-+
| | subnet | | subnet| +---------+ | --->| |
| +--------+ +-------+ | +-+ MC-UE
| | | |
+----+----------+---------+-------+-----+
| | | |
V V V V
------------NS transport ----------------
| | |
V V V
---------------- ---------------- -----------
| Infrastructure | |Infrastructure | | MC server|
| Domain A | | Domain B | | Domain C |
---------------- ---------------- -----------
Figure 13: Reference for Mission Critical Network Slice.
7. Network Infrastructure for new technologies
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7.1. ICN as a Network Slice
ICN as in Information-Centric Networking is a culmination of multiple
future Internet research efforts in various parts of the world, now
being pursued under IRTF's research task group called [ICNRG].
7.1.1. Information Centric Networks Description
Information-Centric Networking (ICN) addresses Internet's network
architectural design gaps based on evolving applications requirements
and end user behavior which is significantly different from what IP
was designed for, which was optimized for host-to-host communication
paradigm. ICN is a non-IP paradigm based on name-based routing and
offers many desirable networking features to applications such as,
caching, mobility, multicasting and computing in a manner different
from traditional host-centric communication model. With respect to
5G and network slicing, ICN paradigm is in line with the move towards
service-centric architectures enabled through frameworks like SDN,
NFV, and Edge Computing. At a high level, ICN offers a name-based
abstraction to application that doesn't require further translation
(as in domain names to IP mapping in current IP networking), making
it suitable to several communication modalities such as multi-point-
to-multi-point, D2D and Ad hoc communication.
7.1.1.1. New Verticals - ICN based service delivery
Services over ICN slices can take advantage of its features such as:
(1) In ICN, applications, services and content are addressed using
names, hence end host resolution services like DNS can be
avoided, this achieves name resolution to edge content or
services without incurring additional RTT delays.
(2) Service flows will be offered mobility and multicasting support,
as the networking is session-less and optimized towards
efficient movement of named data or networking named services
and host level communication.
(3) Services can be deployed at the very edges with ease as ICN
routers are compute friendly, this is because states in the
forwarding table can be that of either content or service
resources.
(4) Further saving bandwidth in the upstream link through
opportunistic caching is an inherent feature of ICN, this also
leads to energy efficient networking.
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7.1.1.2. Considerations for Information Centric Network Applications
When offered as a programmable and customizable logical network
slice, ICN based services can be offered as a network slice in
parallel with traditional IP based services. ICN can be realized as
a slice [_5GICN_] based on the choice of data plane resource offered
by the operators in different segments of the network such as the
access, core network or main data centers. While the same resources
can be used to support services over IP, proper resource isolation
shall allow it to co-exist with ICN slices as well. ICN though
initially was aimed to serve CDN applications such as video-on-demand
or general web content distribution, it is equally adept to server
real-time applications such as audio/video conferencing [ICN-AV], AR/
VR applications, or IoT services. ICN slices can be offered over a
network slicing framework built upon a programmable pool of software
and/or hardware based data plane resources. Heterogeneous mix of
pool of infrastructure resourcesis possible such as : Hardware
decoupled network functions as in containers or VMs. Deeply
programmable hardware resources include GPU, FPGAs [ClickNP], Smart
NIC [Netronome] operated using P4 abstractions, that are supported
over x-86 platform. Programmable hardware may also include
commercial chips supported using P4 or POF allowing one to realize
high performing novel data planes, e.g. [Barefoot]
7.1.2. ICN Type Slices Asks
In ICN, applications use Interest/Data abstractions over named
resources resolved by ICN's routing plane. An ICN slice shall be a
programmable ICN-domain, in which content learning and distribution
will be done using existing or new ICN aware routing and data plane
protocols. As a result, it should be possible to deploy network
functions such as ICN routers and content producers and distributors
that serve and speak ICN protocols. Just as multiple service
instances can be part of a slice, an ICN slices can multiplex
heterogeneous services; on the other hand an ICN slice can be as
granular as a service instance too. The latter approach has
implications with respect to consumer privacy, access control of name
data objects, and granularity of mobility handling.
7.1.3. Required Characteristics
A basic ICN slice can be manifested as a resource isolated logical
network while sharing resources with other connectivity or service
slices. An ICN slice relies on programmability and virtualization
framework to manage the service slices, to allow maximum flexibility
through ICN aware logically centralized control plane for icn service
and slice management.
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o Through a network slice template -ICN service providing entity
could specify specific locations (edge of network domains) to
deploy ICN-routers or other ICN-NFs (ICN aware network functions).
Its service definition varies with the type of service, for e.g.
in case of a VoD service, it can include the demand with respect
user popularity distribution for a particular set of content,
distributed cache or storage resource, and compute resources to
execute video-centric service functions.
o An ability to establish connectivity between ICN network elements
in all segments and create an ICN based virtual topology. This
can be done using specific service control plane based on
application events arriving in a dynamic manner.
o Mechanism to carry ICN user traffic over the infrastructure, ICN
slice can be made aware to the RAN explicitly by integrating ICN
NF with the eNodeB or implicitly using traffic classification
function at the edge and tunneled to ICN user plane functin (UPF)
or can be enabled in an overlay manner. The close the ICN network
is to the UE, better will be the affect on overall efficiency in
terms of bandwidth, latency and energy consumption.
o In addition, bandwidth and other network resources may be
requested from the underlay depending on its capability of
providing deterministic or statisticaly guarnatees.
How multiple services will be deployed within an ICN aware slice may
or may not be exposed to the network operator, depending on if the
ICN slices are natively managed by it or a by other service
providers.
7.2. Network Slices in Communication Endpoints
In this section connected endpoint use case are described to
highlight significance of slicing in an end point.
7.2.1. Connected Vehicle
Connected vehicles are example of scenarios where a communication end
point is split into 3 different type of services that vary in in
terms of topology, bandwidth, latency, mobility and security.
a V2I in short-range: requires ad hoc routing protocol, reliable
data plane and higher layer security and authentication;
b Traditional broadband for Infotainment: requires high speed
connection bandwidth.
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c In network assistance for localized services: low speed, reliable
connection for a short period of time. This service need to be
highly secure and isolated because it connects vehicle to
manufacturers who can alter component settings.
7.2.2. Sliced Terminal
a terminal, if authorized may be allocated dedicated resource for
mission critical services and best-effort slice for normal
connectivity.
7.2.3. Required Characteristics
A network operator that registers a subscriber is required to know
how a terminal is used and which services, offered as a slice it is
part of. A highly secure 3-way authentication between an operator,
service provider and terminal is required to enable a slice on a
device.
8. Overall Use case Analysis
The discussion in above use cases can be summarized as following in
terms of the requirements for network slicing framework.
8.1. Requirements Reference
The following functional requirements are derived from discussions in
above sections. They are described in details in
[I-D.qiang-netslices-gap-analysis] document:
o Req.1 Network Slicing Resource Specification
o Req.2 Cross-Network Segment & Cross-Domain Negotiation
o Req.3 Guaranteed Slice Performance and Isolation
o Req.4 Slice Identification
o Req.5 NS Domain-Abstraction:
o Req.6 OAM Operations with Customized Granularity
The differentiated services described in this document are to be
supported on a common network infrastructure. They also demonstrate
several common functionalities. Therefore, a homogenous approach
towards deployment and management is absolutely necessary.
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8.2. Mapping Common characteristics to Requirements
8.2.1. Req.1 Network Slicing Resource Specification
1. Resource Reservation: compute and network resources are reserved
as part of initial creation and later maintenance of a slice.
For example, a service may initially reserve resources for its
own control plane, and then later it may reserve user plane flows
for applications on demand. Reference use cases: Differentiated
services discussed in section "Services with Resource Assurance".
2. Transparency: Network slicing does not change the functionality
of a scenario; It only facilitates creation of an isolated, an
independently run infrastructure for that use case over a common
network. Transparency promotes inter-operability and a common
resource specification enables it.
3. Multi-access knowledge: Many services are scoped within an access
domain that could be either wireless technologies or different
cellular spectrum. Each network domain or segment has different
characteristics, for example, it may use layer-2, layer-3 or MPLS
connectivity or cellular network. Dissemination of resource
characteristics should be done uniformly across all networks to
simplify slice deployment.
4. Multi-dimensional service vertical: Network slicing supports
dynamic multi-services, multi-tenancy and the means for backing
vertical market players
8.2.2. Req.2 Cross-Network Segment & Cross-Domain Negotiation
1. Multi-domain coordination: Multi-domain refers to different
technology related network domains. For example, it may be RAN,
DSL etc, mobile core network, ISP or different domains in
transport networks such as carrier ethernet, MPLS, TE-tunnel etc.
Often, they are under same administrator's control but may
require coordination across different administration. All
scenarios mentioned require multi-domain coordination to connect
and administer different subnets.
2. Automated Network Slice Management: Network slicing would need to
be self-managed with automated deployment in order to cope with
scalability.
3. Resource Assurance: Meet low latency or bandwidth demands: All
scenarios require agile resource adjustments. it may not be
possible to achieve this using centralize or API approach. It
can also be difficult to coordinate across different domains.
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Therefore, a network slice transport protocol that standardizes
resource propagation in different subnets is needed. It is
important for protocol (or interface) to be lightweight and
distributed.
8.2.3. Req.3 Guaranteed Slice Performance and Isolation
1. Performance Isolation: resource or traffic congestion in a slice
should not affect traffic on other slices sharing the same
infrastructure.
2. Secure Isolation: network services hosted on a slice should not
be able to breach into other slices deployed over the same
infrastructure, e.g. a network function should not be able to
intercept or inject traffic on another slice it is not connected
to.
3. Operational Isolation: Each network slice may have its own
operator that sees this slice as a complete network (i.e router
instances, programmability, using any appropriate communication
protocol, caches, provide dynamic placement of virtual network
functions according to traffic patterns, to use its own
controller, finally it can manage its network as its own).
4. Reliability: It is an important resource attribute in the type of
service verticals described above. Many services verticals
cannot deliver functionality unless the network is reliable (See
remote industry operation, remote surgery and other uRLLC
applications).
8.2.4. Req.4 Slice Identification
1. Agile resource adjustment: all scenarios require meeting low
latency or bandwidth demands. It may not be always possible to
achieve this using centralize or API approach in all deployment
scenario. It can also be difficult to coordinate across
different domains. Therefore, a network slice transport protocol
that standardizes resource propagation in different subnets is
needed. It is important for protocol (or interface) to be
lightweight and distributed.
2. Function Sharing: a given physical or virtual function or
possibly slice subnet may be interconnected with more than one
slice simultaneously. Examples include a client device or, in
3GPP systems, the AMF. An auto discovery of such attributes is
necessary as an exception to isolation.
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3. Slice identification: It is needed to uniquely specify and
resolve resources and for slice-lifecycle in management plane.
In control and data plane identification isolates and secures
resources among the slices.
8.2.5. Req.5 NS Domain-Abstraction
1. Abstraction: Network slicing introduces an additional layer of
abstraction by the creation of logically or physically isolated
groups of network resources and network function/virtual network
functions configurations separating its behavior from the
underlying physical network.
2. Subnet Concept: Functionality of each use case can be logically
split into slice subnets. Each subnet supports only a part of
functionality or interconnection. For example, a segment is
dedicated to virtualized function chain using NFV, another
segment maybe radio-based and third segment may be an edge cloud
node in cellular network. The total resource consumption of a
slice is sum of resources in each of these segments. Therefore,
a proper abstract or logical representation of these subnets is
mandatory. A provider transport network with assured network
resources will be required to inter-connect these subnets.
3. Virtualization of Network Functions: NFV plays an important role
in terms of dynamic placement of services, partitioning of
network resource and configuring the network (physical/virtual)
functions. For example, Ability to run own control and data
plane as needed in mMTC or ICN case.
8.2.6. Req.6 OAM Operations with Customized Granularity
1. Independent per slice management plane: Since a sliced network is
purpose-built, the intelligence to run, control, manage, operate
and administer a slice is with the provider of service in a
slice.
8.3. Mapping Common Characteristics to Requirements
The above discussion is summarized in Figure 14 as below:
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+--------------------------------------------------+----------------+
| Scenario/ | driving factors | Mapped |
| service | | Requirements |
+--------------------------------------------------+----------------+
| eMBB,uRLLC,| (a) uniform resource reservation | REQ.1 |
| mMTC | (b) multi-access connectivity | |
| | (c) transparency for portability | |
| 3GPP | and inter-operability to support | |
| NSaaS | differentiated service verticals.| |
+--------------------------------------------------+----------------+
| AR/VR,V2X | Total resource required is sum of | REQ.2 |
| | resource in each network segment | |
| | and a coordination of what is | |
| | available or not and dynamic | |
| | adjustment is necessary. | |
+--------------------------------------------------+----------------+
| NSaaS, 3GPP| Need mechanisms to ensure | REQ.3 |
| e.g remote | (a) E2E resource Isolation | |
| surgery, | (b) Secure Isolation | |
| industry | (c) Operational Isolation | |
|emergency | | |
+--------------------------------------------------+----------------+
| | mechanisms to support | REQ.4 |
| e.g core | (a) agile resource adjustment | |
| network, | (b) Function sharing | |
| V2X, emer- | (c) Operational Isolation | |
| gency servcs| (d) slice identification | |
+--------------------------------------------------+----------------+
| | To offer a service and | REQ.5 |
| NSaaS | coordinate across different tech- | |
| | nologies: | |
| | (a) Abstraction is important | |
| | both for network and resource. | |
| | (b) abstract each partitioned net- | |
| | work via logical sub-network | |
| | concept. | |
+--------------------------------------------------+----------------+
| | (a) Independent per slice manage- | REQ.6 |
| NSaaS | ment plane | |
| | (b) E2E orchestration | |
+--------------------------------------------------+----------------+
Figure 14
Table: Mapping Common Characteristics to Requirements
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8.4. Other Challenges and Considerations
These observations impose several challenges on network transport.
(1) Within each domain different traffic engineering techniques may
be deployed, for example, FlexE, MPLS, RSVP-TE, DETNET or SDN
based TE. 2(1) Within each domain different transport
techniques may be deployed, for example L2 or L3 virtual
networks such as VLAN, GUE, VxLAN, etc. or Software Function
Chaining (SFC) such as NSH.
(2) No two network infrastructures are alike, technologies such as,
edge computing, NFV, SDN, cloud are partially deployed today.
There is no uniformity about whether a service is available as a
physical node or a virtual node. A network slice framework need
to be able to cater to all cases.
(3) Optimal placement of resources on-demand is only possible when
infrastructure supports it. A capability exposure of a domain
could facilitate such functions.
(4) At a massive scale, it is extremely complex to centralize global
view of resources and be able to distribute on-demand.
Considerations may be made to incorporate domain-to-domain
communication about data and control for a specific network
slice.
Network operators would exploit network slicing for:
o Significantly reducing operational expenditures, allowing
programmability necessary to enrich the offered tailored services.
o Providing the means for network programmability
o Additional business offerings to OTT and other vertical market
players without changing the physical infrastructure (i.e. Health
Vertical Sector, Energy Vertical Sector, Automotive Vertical
Sector, Media and Entertainment Vertical Sector, Factory-of-the-
Future Vertical Sector, Smart Home Vertical Sector, Smart City
Vertical Sector, Additional Specialized Services Vertical Sector.
9. Conclusion
A service should typically need a network slice for one of those
reasons:
(1) The service cannot provide optimal experience on a best-effort
network.
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(2) It is inefficient and expensive to build a separate
infrastructure.
The separation from a generalized network, should allow new services
to use newer or different protocols in network, transport and
management layer/plane for that service (as in the case of ICN, mMTC,
uRLL). The goal of Network slices is to offer enriched service
verticals with very different network capability and performance
demands but also simplify from the traditional service delivery
models.
There is need for a uniform framework for end to end network slicing
specifications that spans across multiple technology domains and can
drive extensions in those technolgy-areas for support of Network
slices.
10. Security Considerations
The security considerations apply to each slice. In addition general
security considerations of underlying infrastructure whether isolated
communication with in a slice apply for links using wireless
technologies.
11. IANA Considerations
There are no IANA actions requested at this time.
12. Acknowledgements
Thanks to the following reviewers for providing details for several
use cases and for helping with review of the document.
Stewart Bryant ([email protected], Hannu Flinck
([email protected]), Med Boucadair
([email protected]), Dong Jie ([email protected]).
13. References
13.1. Normative References
[I-D.dt-detnet-dp-sol]
Korhonen, J., Andersson, L., Jiang, Y., Varga, B., Farkas,
J., Bernardos, C., and T. Mizrahi, "DetNet Data Plane
solution", draft-dt-detnet-dp-sol-00 (work in progress),
March 2017.
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[I-D.pularikkal-virtual-cpe]
Pularikkal, B., Fu, Q., Hui, D., Sundaram, G., and S.
Gundavelli, "Virtual CPE Deployment Considerations",
draft-pularikkal-virtual-cpe-02 (work in progress),
February 2017.
[I-D.qiang-netslices-gap-analysis]
Qiang, L., Martinez-Julia, P., 67, 4., Dong, J.,
[email protected], k., Galis, A., Hares, S., and
S. Slawomir, "Gap Analysis for Network Slicing", draft-
qiang-netslices-gap-analysis-00 (work in progress), June
2017.
[RFC6770] Bertrand, G., Ed., Stephan, E., Burbridge, T., Eardley,
P., Ma, K., and G. Watson, "Use Cases for Content Delivery
Network Interconnection", RFC 6770, DOI 10.17487/RFC6770,
November 2012, <http://www.rfc-editor.org/info/rfc6770>.
13.2. Informative References
[_5GICN_] IEEE Communication, "Delivering ICN Services in 5G using
Network Slicing. 'Asit Chakraborti, Syed Obaid Amin,
Aytac Azgin, Ravi Ravindran, G.Q.Wang'", May 2017,
<https://arxiv.org/abs/1610.01182>.
[Barefoot]
Barefoot, "Barefoot", 2017,
<https://barefootnetworks.com>.
[ClickNP] ACM SIGCOMM, "ClickNP: Highly Flexible and High
Performance Network Processing with Reconfigurable
Hardware. 'B. Li, et al'", 2017,
<https://www.microsoft.com/en-us/research/wp-
content/uploads/2016/07/main-4.pdf>.
[ICN-AV] IEEE Transaction on Emerging Network Architecture (under
submission),, "SRMCA: Scalable and Realiable Multimedia
Communication Architecture. 'Asit Chakraborti, Syed Obaid
Amin, Aytac Azgin, Ravi Ravindran, G.Q.Wang.'", 2017,
<https://arxiv.org/abs/1703.03070>.
[ICNRG] IRTF, "ICN Routing Group", November 2016,
<https://irtf.org/icnrg>.
[Netronome]
Netronome, "Netronome", 2017,
<https://www.netronome.com/products/agilio-cx/>.
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[TR_3GPP.33.899]
3GPP, "Study on the security aspects of the next
generation system", 3GPP TR 33.899 0.6.0, November 2016,
<http://www.3gpp.org/ftp/Specs/html-info/33899.htm>.
[TR_3GPP.38.801]
3GPP, "Study on new radio access technology Radio access
architecture and interfaces", 3GPP TR 38.801 1.0.0, March
2017, <http://www.3gpp.org/ftp/Specs/html-info/38801.htm>.
[TR_3GPP_38.913]
3GPP, "Study on scenarios and requirements for next
generation access technologies", 3GPP TR 38.913 14.2.0,
March 2017,
<http://www.3gpp.org/ftp/Specs/archive/38_series/38.913>.
[TS_3GPP.23.501]
3GPP, "System Architecture for the 5G System", 3GPP
TS 23.501 0.2.0, February 2017,
<http://www.3gpp.org/ftp/Specs/html-info/23501.htm>.
[TS_3GPP.23.502]
3GPP, "Procedures for the 5G System", 3GPP TS 23.502
0.2.0, February 2017,
<http://www.3gpp.org/ftp/Specs/html-info/23502.htm>.
[TS_3GPP.28.500]
3GPP, "Telecommunication management; Management concept,
architecture and requirements for mobile networks that
include virtualized network functions", 3GPP TS 28.500
1.3.0, 11 2016,
<http://www.3gpp.org/ftp/Specs/html-info/28500.htm>.
[VCPEBBF] Broadband Forum, "TR-345 Broadband Network Gateway and
Network Function Virtualization", Dec 2016,
<https://www.broadband-forum.org/technical/download/TR-
345.pdf>.
[White-paper-5GAA]
5G Automotive Association, "The Case for Cellular V2X for
Safety and Cooperative Driving", November 2016,
<http://www.5gaa.org/
pdfs/5GAA-whitepaper-23-Nov-2016.pdf>.
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Authors' Addresses
Kiran Makhijani
Huawei Technologies
2890 Central Expressway
Santa Clara CA 95050
Email: [email protected]
Jun Qin
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
Email: [email protected]
Ravi Ravindran
Huawei Technologies
2890 Central Expressway
Santa Clara CA 95050
Email: [email protected]
Liang Geng
China Mobile
Beijing 100095
Email: [email protected]
Li Qiang
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
Email: [email protected]
Shuping Peng
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
Email: [email protected]
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Xavier de Foy
InterDigital Inc.
1000 Sherbrooke West
Montreal
Canada
Email: [email protected]
Akbar Rahman
InterDigital Inc.
1000 Sherbrooke West
Montreal
Canada
Email: [email protected]
Alex Galis
University College London
London
U.K.
Email: [email protected]
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