< draft-contreras-teas-slice-nbi-00.txt		draft-contreras-teas-slice-nbi-01.txt >
	TEAS Working Group LM. Contreras		TEAS Working Group LM. Contreras
	Internet-Draft Telefonica		Internet-Draft Telefonica
	Intended status: Informational S. Homma		Intended status: Informational S. Homma
	Expires: May 7, 2020 NTT		Expires: September 10, 2020 NTT
	J. Ordonez-Lucena		J. Ordonez-Lucena
	Telefonica		Telefonica
	November 4, 2019		March 9, 2020
	Considerations for defining a Transport Slice NBI		Considerations for defining a Transport Slice NBI
	draft-contreras-teas-slice-nbi-00		draft-contreras-teas-slice-nbi-01
	Abstract		Abstract
	The transport network is an essential component in the end-to-end		The transport network is an essential component in the end-to-end
	delivery of services and, consequently, with the advent of network		delivery of services and, consequently, with the advent of network
	slicing it is necessary to understand what could be the way in which		slicing it is necessary to understand what could be the way in which
	the transport network is consumed as a slice. This document analyses		the transport network is consumed as a slice. This document analyses
	the needs of potential transport slice consumers in order to identify		the needs of potential transport slice consumers in order to identify
	the functionality required on the North Bound Interface (NBI) of a		the functionality required on the North Bound Interface (NBI) of a
	transport slice producer for satisfying such transport slcie		transport slice controller for satisfying such transport slice
	requests.		requests.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	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
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	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 7, 2020.		This Internet-Draft will expire on September 10, 2020.
	Copyright Notice		Copyright Notice
	Copyright (c) 2019 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.
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	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
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	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
	2. Conventions used in this document . . . . . . . . . . . . . . 3		2. Conventions used in this document . . . . . . . . . . . . . . 3
	3. Northbound interface for transport slices . . . . . . . . . . 3		3. Northbound interface for transport slices . . . . . . . . . . 3
	4. Transport slice use cases . . . . . . . . . . . . . . . . . . 4		4. Transport slice use cases . . . . . . . . . . . . . . . . . . 4
	4.1. 5G Services . . . . . . . . . . . . . . . . . . . . . . . 4		4.1. 5G Services . . . . . . . . . . . . . . . . . . . . . . . 4
	4.1.1. Generic Slice Template . . . . . . . . . . . . . . . 5		4.1.1. Generic network Slice Template . . . . . . . . . . . 5
	4.1.2. Categorization of GST attributes . . . . . . . . . . 6		4.1.2. Categorization of GST attributes . . . . . . . . . . 6
	4.1.2.1. Attributes with direct impact on the transport		4.1.2.1. Attributes with direct impact on the transport
	slice definition . . . . . . . . . . . . . . . . 7		slice definition . . . . . . . . . . . . . . . . 7
	4.1.2.2. Attributes with indirect impact on the transport		4.1.2.2. Attributes with indirect impact on the transport
	slice definition . . . . . . . . . . . . . . . . 7		slice definition . . . . . . . . . . . . . . . . 7
	4.1.2.3. Attributes with no impact on the transport slice		4.1.2.3. Attributes with no impact on the transport slice
	definition . . . . . . . . . . . . . . . . . . . 8		definition . . . . . . . . . . . . . . . . . . . 8
	4.2. NFV-based services . . . . . . . . . . . . . . . . . . . 8		4.1.3. Provisioning procedures . . . . . . . . . . . . . . . 9
	5. Security Considerations . . . . . . . . . . . . . . . . . . . 9		4.2. NFV-based services . . . . . . . . . . . . . . . . . . . 9
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9		4.3. Network sharing . . . . . . . . . . . . . . . . . . . . . 10
	7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9		5. Security Considerations . . . . . . . . . . . . . . . . . . . 10
	7.1. Normative References . . . . . . . . . . . . . . . . . . 9		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
	7.2. Informative References . . . . . . . . . . . . . . . . . 9		7. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9		7.1. Normative References . . . . . . . . . . . . . . . . . . 11
			7.2. Informative References . . . . . . . . . . . . . . . . . 11
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
	1. Introduction		1. Introduction
	A number of new technologies, such as 5G, NFV and SDN are not only		A number of new technologies, such as 5G, NFV and SDN are not only
	evolving the network from a pure technological perspective but also		evolving the network from a pure technological perspective but also
	are changing the concept in which new services are offered to the		are changing the concept in which new services are offered to the
	customers [I-D.homma-slice-provision-models] by introducing the		customers [I-D.homma-slice-provision-models] by introducing the
	concept of network slicing.		concept of network slicing.
	The transport network is an essential component in the end-to-end		The transport network is an essential component in the end-to-end
	delivery of services and, consequently, it is necessary to understand		delivery of services and, consequently, it is necessary to understand
	what could be the way in which the transport network is consumed as a		what could be the way in which the transport network is consumed as a
	slice.		slice. For a definition of transport slice refer to
			[I-D.nsdt-teas-transport-slice-definition].
	In this document it is assumed that there exists a (logically)		In this document it is assumed that there exists a (logically)
	centralized component in the transport network, namely Transport		centralized component in the transport network, namely Transport
	Slice Producer (TSP) with the responsibilities on the control and		Slice Controller (TSC) with the responsibilities on the control and
	management of the transport slices invoked for a given service, as		management of the transport slices invoked for a given service, as
	requested by Transport Slice Consumers (TSC).		requested by Transport Slice Consumers.
	This document analyses the needs of potential transport slice		This document analyses the needs of potential transport slice
	consumers in order to identify the functionality required on the		consumers in order to identify the functionality required on the
	North Bound Interface (NBI) of the TSP to be exposed towards such		North Bound Interface (NBI) of the TSC to be exposed towards such
	transport slice consumers. Solutions to construct the requested		transport slice consumers. Solutions to construct the requested
	transport slices are out of scope of this document.		transport slices are out of scope of this document.
	This document addresses some of the discussions of the TEAS Slice		This document addresses some of the discussions of the TEAS Slice
	Design Team. However it is not at this stage an official outcome of		Design Team. However, it is not at this stage an official outcome of
	the Design Team.		the Design Team.
	2. Conventions used in this document		2. Conventions used in this document
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC2119 [RFC2119].		document are to be interpreted as described in RFC2119 [RFC2119].
	3. Northbound interface for transport slices		3. Northbound interface for transport slices
	In a general manner, the transport network supports different kinds		In a general manner, the transport network supports different kinds
	of services. These services consume the transport network provided		of services. These services consume capabilities provided by the
	capabilities for deploying end-to-end services, interconnecting		transport network for deploying end-to-end services, interconnecting
	network functions or applications spread across the network and		network functions or applications spread across the network and
	providing connectivity toward the final users of these services.		providing connectivity toward the final users of these services.
	Under the slicing approach, a transport slice consumer requests to a		Under the slicing approach, a transport slice consumer requests to a
	transport slice producer a slice with certain characteristics and		transport slice controller a slice with certain characteristics and
	parametrization. Such request it is assumed here to be done through		parametrization. Such request it is assumed here to be done through
	an NBI exposed by the TSP to the consumer, as reflected in Fig. 1.		a NBI exposed by the TSC to the consumer, as reflected in Fig. 1.
	+--------------------+		+--------------------+
	| |		| |
	| Transport |		| Transport |
	| Slice Consumer |		| Slice Consumer |
	| |		| |
	+--------------------+		+--------------------+
	A		A
	|		|
	| Transport		| Transport
	| Slice		| Slice
	| NBI		| NBI
	|		|
	V		V
	+--------------------+		+--------------------+
	| |		| |
	| Transport |		| Transport |
	| Slice Producer |		| Slice Controller |
	| (Transport Slicer) |
	| |		| |
	+--------------------+		+--------------------+
	Figure 1: Transport slice NBI concept		Figure 1: Transport slice NBI concept
	The functionality supported by the NBI depends on the requirements		The functionality supported by the NBI depends on the requirements
	that the slice consumer has to satisfy. It is then important to		that the slice consumer has to satisfy. It is then important to
	understand the needs of the slice consumers as well as the way of		understand the needs of the slice consumers as well as the way of
	expressing them.		expressing them.
	skipping to change at page 5, line 12 ¶		skipping to change at page 5, line 11 ¶
	heterogeneity, it is fundamental for the network operator to define a		heterogeneity, it is fundamental for the network operator to define a
	a unified ability to interpret service requirements from different		a unified ability to interpret service requirements from different
	vertical customers, and to represent them in a common language, with		vertical customers, and to represent them in a common language, with
	the purposes of facilitating their translation/mapping into specific		the purposes of facilitating their translation/mapping into specific
	slicing-aware network configuration actions. In this regard, model-		slicing-aware network configuration actions. In this regard, model-
	based network slice descriptors built on the principles of		based network slice descriptors built on the principles of
	reproducibility, reusability and customizability can be defined for		reproducibility, reusability and customizability can be defined for
	this end.		this end.
	As a starting point for such a definition, GSMA developed the idea of		As a starting point for such a definition, GSMA developed the idea of
	having a universal blueprint that can be used by any vertical		having a universal blueprint that, being offered by network
	customer to order the deployment of an NSI based on a specific set of		operators, can be used by any vertical customer to order the
	service requirements. The result of this work has been the		deployment of an NSI based on a specific set of service requirements.
	definition of a baseline network slice descriptor called Generic		The result of this work has been the definition of a baseline network
	Slice Template (GST). The GST contains multiple attributes that can		slice descriptor called Generic network Slice Template (GST). The
	be used to characterize a network slice. A Network Slice Type (NEST)		GST contains multiple attributes that can be used to characterize a
	describes the characteristics of a network slice by means of filling		network slice. A Network Slice Type (NEST) describes the
	GST attributes with values based on specific service requirements.		characteristics of a network slice by means of filling GST attributes
	Basically, a NEST is a filled-in version of a GST. Different NESTs		with values based on specific service requirements. Basically, a
	allow describing different types of network slices. For slices based		NEST is a filled-in version of a GST. Different NESTs allow
	on standardized service types, e.g. eMBB, uRLLC and mIoT, the network		describing different types of network slices. For slices based on
			standardized service types, e.g. eMBB, uRLLC and mIoT, the network
	operator may have a set of readymade, standardized NESTs (S-NESTs).		operator may have a set of readymade, standardized NESTs (S-NESTs).
	For slices based on specific industry use cases, the network operator		For slices based on specific industry use cases, the network operator
	can define additional NESTs.		can define additional NESTs.
	Service requirements from a given vertical customer are mapped to a		Service requirements from a given vertical customer are mapped to a
	NEST, which provides a self-contained description of the network		NEST, which provides a self-contained description of the network
	slice to be provisioned for that vertical customer. According to		slice to be provisioned for that vertical customer. According to
	this reasoning, the NEST can be used by the network operator as input		this reasoning, the NEST can be used by the network operator as input
	to the NSI preparation phase, which is defined in [TS28.530]. 3GPP is		to the NSI preparation phase, which is defined in [TS28.530]. 3GPP is
	working on the translation of the GST/NEST attributes into NSI		working on the translation of the GST/NEST attributes into NSI
	skipping to change at page 5, line 44 ¶		skipping to change at page 5, line 44 ¶
	type from the Network Slice Information Object Class (IOC) in		type from the Network Slice Information Object Class (IOC) in
	[TS28.541]. These requirements are used by the 3GPP Management		[TS28.541]. These requirements are used by the 3GPP Management
	System to allocate the NSI across all network domains, including		System to allocate the NSI across all network domains, including
	transport network. The transport slice defines the part of that NSI		transport network. The transport slice defines the part of that NSI
	that is deployed across the transport network.		that is deployed across the transport network.
	Despite the translation is an on-going work in 3GPP it seems		Despite the translation is an on-going work in 3GPP it seems
	convenient to start looking at the GST attributes to understand what		convenient to start looking at the GST attributes to understand what
	kind of parameters could be required for the transport slice NBI.		kind of parameters could be required for the transport slice NBI.
	4.1.1. Generic Slice Template		4.1.1. Generic network Slice Template
	The structure of the GST is defined in [GSMA]. The template defines		The structure of the GST is defined in [GSMA]. The template defines
	a total of 35 attributes. For each of them, the following		a total of 35 attributes. For each of them, the following
	information is provided:		information is provided:
	o Attribute definition, which provides a formal definition of what		o Attribute definition, which provides a formal definition of what
	the attribute represents.		the attribute represents.
	o Attribute parameters, including:		o Attribute parameters, including:
	skipping to change at page 6, line 27 ¶		skipping to change at page 6, line 27 ¶
	is characterization attribute, it can be further tagged as a		is characterization attribute, it can be further tagged as a
	performance-related attribute, a functionality-related		performance-related attribute, a functionality-related
	attribute or an operation-related attribute.		attribute or an operation-related attribute.
	* Exposure, which allow describing how this attribute interact		* Exposure, which allow describing how this attribute interact
	with the slice consumer, either as an API or a KPI.		with the slice consumer, either as an API or a KPI.
	o Attribute presence, either mandatory, conditional or optional.		o Attribute presence, either mandatory, conditional or optional.
	Attributes from GST can be used by the network operator (slice		Attributes from GST can be used by the network operator (slice
	producer) and a vertical customer (slice consumer) to agree SLA.		controller) and a vertical customer (slice consumer) to agree SLA.
	GST attributes are generic in the sense that they can be used to		GST attributes are generic in the sense that they can be used to
	characterize different types of network slices. Once those		characterize different types of network slices. Once those
	attributes become filled with specific values, it becomes a NEST		attributes become filled with specific values, it becomes a NEST
	which can be ordered by slice consumers.		which can be ordered by slice consumers.
	4.1.2. Categorization of GST attributes		4.1.2. Categorization of GST attributes
	Not all the GST attributes as defined in [GSMA] have impact in the		Not all the GST attributes as defined in [GSMA] have impact in the
	transport network since some of them are specific to either the radio		transport network since some of them are specific to either the radio
	or the mobile core part.		or the mobile core part.
	In the analysis performed in this document, the attributes have been		In the analysis performed in this document, the attributes have been
	categorized as:		categorized as:
	o Attributes that directly impact the definition of the transport		o Directly impactive attributes, which are those that have direct
	slice, i.e., attributes that can be directly translated into		impact on the definition of the transport slice, i.e., attributes
	requirements required to be satisfied by a transport slice.		that can be directly translated into requirements required to be
			satisfied by a transport slice.
	o Attributes that indirectly impact the definition of the transport		o Indirectly impactive attributes, which are thise that impact in an
	slice, i.e., attributes that indirectly impose some requirements		indirect manner on the definition of the transport slice, i.e.,
	to a transport slice.		attributes that indirectly impose some requirements to a transport
			slice.
	o Attributes that do not have impact on the transport slice.		o Non-impactive attributes, that are those which do not have impact
			on the transport slice at all.
	The following sections describe the attributes falling into the three		The following sections describe the attributes falling into the three
	categories.		categories.
	4.1.2.1. Attributes with direct impact on the transport slice		4.1.2.1. Attributes with direct impact on the transport slice
	definition		definition
	The following attributes impose requirements in the transport slice		The following attributes impose requirements in the transport slice
	o Availability		o Availability
	skipping to change at page 8, line 47 ¶		skipping to change at page 9, line 5 ¶
	o Number of terminals		o Number of terminals
	o Positioning support		o Positioning support
	o Radio spectrum		o Radio spectrum
	o Synchronicity (among devices)		o Synchronicity (among devices)
	o V2X communication mode		o V2X communication mode
			4.1.3. Provisioning procedures
			3GPP identifies in [TS28.531] a number of procedures for the
			provisioning of a network slice in general. It can be assumed that
			similar procedures may also apply to a transport slice, facilitating
			a consistent management and control of end-to-end slices.
			The envisioned procedures are the following:
			o Slice instance allocation: this procedure permits to create a new
			slice instance (or reuse an existing one).
			o Slice instance de-allocation: this procedure decommissions a
			previously instantiated slice.
			o Slice instance modification: this procedure permits the change in
			the characteristics of an existing slice instance.
			o Get slice instance status: this procedure helps to retrieve run-
			time information on the status of a deployed slice instance.
			o Retrieval of slice capabilities: this procedure assists on getting
			information about the capabilities (e.g. maximum latency
			supported).
			All these procedures fit in the operation of transport network
			slices.
	4.2. NFV-based services		4.2. NFV-based services
	To do.		NFV technology allows the flexible and dynamic instantiation of
			virtualized network functions (and their composition into network
			services) on top of a distributed, cloud-enabled compute
			infrastructure. This infrastructure can span across different points
			of presence in a carrier network. By leveraging on transport network
			slicing, connectivity services established across geographically
			remote points of presence can be enriched by providing additional QoS
			guarantees with respect present state-of-the-art mechanisms, as
			conventional L2/L3 VPNs.
			ETSI NFV defines the role of WAN Infrastructure Manager (WIM) as the
			component in charge of managing and controlling the connectivity
			external to the PoPs. In [IFA032] a number of interfaces are
			identified to be exposed by the WIM for supporting the multi-site
			connectivity, thus representing the capabilities expected for a
			transport network slice, as well, in case of satisfying such
			connectivity needs by means of the slice concept.
			The interfaces considered are the following:
			o Multi-Site Connectivity Service (MSCS) Management: this interface
			permits the creation, termination, update and query of MSCSs,
			including reservation. It also enables subscription for
			notifications and information retrieval associated to the
			connectivity service.
			o Capacity Management: this interface allows querying about the
			capacity (e.g. bandwidth), topology, and network edge points of
			the connectivity service, as well as about information of consumed
			and available capacity on the underlying network resources.
			o Fault Management: this interface serves for the provision of
			alarms related to the MSCSs.
			o Performance Management: this interface assists on the retrieval of
			performance information (measurement results collection and
			notifications) related to MSCSs.
			The connectivity services themselves are expressed through a number
			of attributes, including bandwidth (for egress and ingress
			directions), QoS metrics, directionality (i.e., unidirectional or
			bidirectional service), MTU, connectivity type (e.g., multi-point)
			and protection scheme (e.g., 1;1, 1+1, etc.), among others. All
			those attributes will assist on the characterization of the
			connectivity slice to be deployed, and thus, are relevant for the
			definition of a transport slice supporting such connectivity.
			Author's note: Detail on attributes will be provided in a forthcoming
			version.
			4.3. Network sharing
			To be done.
	5. Security Considerations		5. Security Considerations
	This draft does not include any security considerations.		This draft does not include any security considerations.
	6. IANA Considerations		6. IANA Considerations
	This draft does not include any IANA considerations		This draft does not include any IANA considerations
	7. References		7. References
	7.1. Normative References		7.1. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	7.2. Informative References		7.2. Informative References
	[GSMA] "Generic Network Slice Template, version 1.0", NG.116 ,		[GSMA] "Generic Network Slice Template, version 2.0", NG.116 ,
	May 2019.		October 2019.
	[I-D.homma-slice-provision-models]		[I-D.homma-slice-provision-models]
	Homma, S., Nishihara, H., Miyasaka, T., Galis, A., OV, V.,		Homma, S., Nishihara, H., Miyasaka, T., Galis, A., OV, V.,
	Lopez, D., Contreras, L., Ordonez-Lucena, J., Martinez-		Lopez, D., Contreras, L., Ordonez-Lucena, J., Martinez-
	Julia, P., Qiang, L., Rokui, R., Ciavaglia, L., and X.		Julia, P., Qiang, L., Rokui, R., Ciavaglia, L., and X.
	Foy, "Network Slice Provision Models", draft-homma-slice-		Foy, "Network Slice Provision Models", draft-homma-slice-
	provision-models-01 (work in progress), July 2019.		provision-models-02 (work in progress), November 2019.
			[I-D.nsdt-teas-transport-slice-definition]
			Rokui, R., Homma, S., and K. Makhijani, "IETF Definition
			of Transport Slice", draft-nsdt-teas-transport-slice-
			definition-00 (work in progress), November 2019.
			[IFA032] "IFA032 Interface and Information Model Specification for
			Multi-Site Connectivity Services V3.2.1.", ETSI GS NFV-IFA
			032 V3.2.1 , April 2019.
	[TS28.530]		[TS28.530]
	"TS 28.530 Management and orchestration; Concepts, use		"TS 28.530 Management and orchestration; Concepts, use
	cases and requirements (Release 16) V16.0.0.", 3GPP TS		cases and requirements (Release 16) V16.0.0.", 3GPP TS
	28.530 V16.0.0 , September 2019.		28.530 V16.0.0 , September 2019.
	[TS28.541]		[TS28.541]
	"TS 28.541 Management and orchestration; 5G Network		"TS 28.541 Management and orchestration; 5G Network
	Resource Model (NRM); Stage 2 and stage 3 (Release 16)		Resource Model (NRM); Stage 2 and stage 3 (Release 16)
	V16.2.0.", 3GPP TS 28.541 V16.2.0 , September 2019.		V16.2.0.", 3GPP TS 28.541 V16.2.0 , September 2019.
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