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draft-ietf-ccamp-yang-otn-slicing.txt
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CCAMP Working Group A. Guo
Internet-Draft Futurewei Technologies
Intended status: Standards Track L.M. Contreras
Expires: 28 December 2024 Telefonica
S. Belotti
Nokia
R. Rokui
Ciena
Y. Xu
CAICT
Y. Zhao
China Mobile
X. Liu
Alef Edge
26 June 2024
Framework and Data Model for OTN Network Slicing
draft-ietf-ccamp-yang-otn-slicing-07
Abstract
The requirement of slicing network resources with desired quality of
service is emerging at every network technology, including the
Optical Transport Networks (OTN). As a part of the transport
network, OTN can provide hard pipes with guaranteed data isolation
and deterministic low latency, which are highly demanded in the
Service Level Agreement (SLA).
This document describes a framework for OTN network slicing and
defines YANG data models with OTN technology-specific augments
deployed at both the north and south bound of the OTN network slice
controller. Additional YANG data model augmentations will be defined
in a future version of this draft.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Guo, et al. Expires 28 December 2024 [Page 1]
Internet-Draft Framework and YANG of OTN Slices June 2024
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 28 December 2024.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Prefixes in Data Node Names . . . . . . . . . . . . . . . 3
1.3. Definition of OTN Slice . . . . . . . . . . . . . . . . . 4
2. Use Cases for OTN Network Slicing . . . . . . . . . . . . . . 5
2.1. Leased Line Services with OTN . . . . . . . . . . . . . . 6
2.2. Co-construction and Sharing . . . . . . . . . . . . . . . 6
2.3. Wholesale of optical resources . . . . . . . . . . . . . 6
2.4. Vertical dedicated network with OTN . . . . . . . . . . . 7
2.5. End-to-end network slicing . . . . . . . . . . . . . . . 7
3. Framework for OTN slicing . . . . . . . . . . . . . . . . . . 8
4. Realizing OTN Slices . . . . . . . . . . . . . . . . . . . . 11
5. YANG Data Model for OTN Slicing Configuration . . . . . . . . 14
5.1. OTN Slicing YANG Model for MPI . . . . . . . . . . . . . 14
5.1.1. MPI YANG Model Overview . . . . . . . . . . . . . . . 14
5.1.2. MPI YANG Model Tree . . . . . . . . . . . . . . . . . 14
5.1.3. MPI YANG Code . . . . . . . . . . . . . . . . . . . . 15
5.2. OTN Slicing YANG Model for OTN-SC NBI . . . . . . . . . . 18
5.2.1. NBI YANG Model Overview . . . . . . . . . . . . . . . 18
5.2.2. NBI YANG Model Tree for OTN slice . . . . . . . . . . 19
5.2.3. NBI YANG Code for OTN Slice . . . . . . . . . . . . . 21
6. Manageability Considerations . . . . . . . . . . . . . . . . 28
7. Security Considerations . . . . . . . . . . . . . . . . . . . 28
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 29
Guo, et al. Expires 28 December 2024 [Page 2]
Internet-Draft Framework and YANG of OTN Slices June 2024
9.1. Normative References . . . . . . . . . . . . . . . . . . 30
9.2. Informative References . . . . . . . . . . . . . . . . . 32
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 33
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34
1. Introduction
The requirement of slicing network resources with desired quality of
service is emerging at every network technology, including the
Optical Transport Networks (OTN). As a part of the transport
network, OTN can provide hard pipes with guaranteed data isolation
and deterministic low latency, which are highly demanded in the
Service Level Agreement (SLA). This document describes a framework
for OTN network slicing and defines YANG data models with OTN
technology-specific augments deployed at both the north and south
bound of the OTN network slice controller. Additional YANG data
model augmentations will be defined in a future version of this
draft.
1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
The terminology for describing YANG data models is found in
[RFC7950].
1.2. Prefixes in Data Node Names
In this document, names of data nodes and other data model objects
are prefixed using the standard prefix associated with the
corresponding YANG imported modules, as shown in Table 1.
Guo, et al. Expires 28 December 2024 [Page 3]
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+==========+============================+===========+
| Prefix | YANG Module | Reference |
+==========+============================+===========+
| yang | ietf-yang-types | [RFC6991] |
+----------+----------------------------+-----------+
| inet | ietf-inet-types | [RFC6991] |
+----------+----------------------------+-----------+
| nt | ietf-network-topology | [RFC8345] |
+----------+----------------------------+-----------+
| nw | ietf-network-topology | [RFC8345] |
+----------+----------------------------+-----------+
| tet | ietf-te-topology | [RFC8795] |
+----------+----------------------------+-----------+
| ietf-nss | ietf-network-slice-service | [RFCVVVV] |
+----------+----------------------------+-----------+
| te-types | ietf-te-types | [RFCWWWW] |
+----------+----------------------------+-----------+
| otnt | ietf-otn-topology | [RFCYYYY] |
+----------+----------------------------+-----------+
| l1-types | ietf-layer1-types | [RFCZZZZ] |
+----------+----------------------------+-----------+
| otns | ietf-otn-slice | [RFCXXXX] |
+----------+----------------------------+-----------+
| otns-mpi | ietf-otn-slice-mpi | [RFCXXXX] |
+----------+----------------------------+-----------+
Table 1: Prefixes and Corresponding YANG Modules
RFC Editor Note: Please replace VVVV with the RFC number assigned to
[I-D.ietf-teas-ietf-network-slice-nbi-yang]. Please replace WWWW
with the RFC number assigned to [I-D.ietf-teas-rfc8776-update].
Please replace XXXX with the RFC number assigned to this document.
Please replace YYYY with the RFC number assigned to
[I-D.ietf-ccamp-otn-topo-yang]. Please replace ZZZZ with the RFC
number assigned to [I-D.ietf-ccamp-layer1-types]. Please remove this
note.
1.3. Definition of OTN Slice
An OTN slice is an OTN virtual network topology connecting a number
of OTN endpoints using a set of shared or dedicated OTN network
resources to satisfy specific service level objectives (SLOs).
An OTN slice is a technology-specific realization of the RFC 9543
network slice service [RFC9543] in the OTN domain, with the
capability of configuring slice resources in the term of OTN
technologies. Therefore, all the terms and definitions concerning
network slicing as defined in [RFC9543] apply to OTN slicing.
Guo, et al. Expires 28 December 2024 [Page 4]
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An OTN slice can span multiple OTN administrative domains,
encompassing access links, intra-domain paths, and inter-domain
links. An OTN slice may include multiple endpoints, each associated
with a set of physical or logical resources, e.g. optical port or
time slots, at the termination point (TP) of an access link or inter-
domain link at an OTN provider edge (PE) equipment.
An end-to-end OTN slice may be composed of multiple OTN segment
slices in a hierarchical or sequential (or stitched) combination.
Figure 1 illustrates the scope of OTN slices in multi-domain
environment.
<------------------End-to-end OTN Slice---------------->
<- OTN Segment Slice 1 ---> <-- OTN Segment Slice 2 -->
+-------------------------+ +-----------------------+
| +-----+ +-------+ | | +-------+ +-----+|
+----+ | | OTN | | OTN | | | | OTN | | OTN || +----+
| CE +-+-o PE +-...--+ Borde o--+--+-o Borde +-...--+ PE o+--+ CE |
+----+||/| | | Node |\ || | | Node | | || |+----+
|||+-----+ +-------+| || | +-------+ +-----+| |
||| OTN Domain 1 | || | OTN Domain 2 | |
|++----------------------+-+| +-----------------------+ |
| | | | |
| +-----+ +-----------+ | |
| | | | |
V V V V V
Access OTN Slice Inter-domain Access
Link Endpoint Link Link
Figure 1: OTN Slice
OTN slices may be pre-configured by the management plane and
presented to the customer via the northbound interface (NBI), or be
dynamically provisioned by a higher layer slice controller, e.g., an
RFC 9543 network slice controller (NSC) through the NBI. The OTN
slice is provided by a service provider to a customer to be used as
though it was part of the customer's own networks.
2. Use Cases for OTN Network Slicing
Guo, et al. Expires 28 December 2024 [Page 5]
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2.1. Leased Line Services with OTN
For end business customers (like OTT or enterprises), leased lines
have the advantage of providing high-speed connections with low
costs. On the other hand, the traffic control of leased lines is
very challenging due to rapid changes in service demands. Carriers
are recommended to provide network-level slicing capabilities to meet
this demand. Based on such capabilities, private network users have
full control over the sliced resources which have been allocated to
them and which could be used to support their leased lines, when
needed. Users may formulate policies based on the demand for
services and time to schedule the resources from the entire network's
perspective flexibly. For example, the bandwidth between any two
points may be established or released based on the time or monitored
traffic characteristics. The routing and bandwidth may be adjusted
at a specific time interval to maximize network resource utilization
efficiency.
2.2. Co-construction and Sharing
Co-construction and sharing of a network are becoming a popular means
among service providers to reduce networking building CAPEX. For Co-
construction and sharing case, there are typically multiple co-
founders for the same network. For example, one founder may provide
optical fibres and another founder may provide OTN equipment, while
each occupies a certain percentage of the usage rights of the network
resources. In this scenario, the network O&M is performed by a
certain founder in each region, where the same founder usually
deploys an independent management and control system. The other
founders of the network use each other's management and control
system to provision services remotely. In this scenario, different
founders' network resources need to be automatically (associated)
divided, isolated, and visualized. All founders may share or have
independent O&M capabilities, and should be able to perform service-
level provisioning in their respective slices.
2.3. Wholesale of optical resources
In the optical resource wholesale market, smaller, local carriers and
wireless carriers may rent resources from larger carriers, or
infrastructure carriers instead of building their networks.
Likewise, international carriers may rent resources from respective
local carriers and local carriers may lease their owned networks to
each other to achieve better network utilization efficiency. From
the perspective of a resource provider, it is crucial that a network
slice is timely configured to meet traffic matrix requirements
requested by its tenants. The support for multi-tenancy within the
resource provider's network demands that the network slices are
Guo, et al. Expires 28 December 2024 [Page 6]
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qualitatively isolated from each other to meet the requirements for
transparency, non-interference, and security. Typically, a resource
purchaser expects to use the leased network resources flexibly, just
like they are self-constructed. Therefore, the purchaser is not only
provided with a network slice, but also the full set of
functionalities for operating and maintaining the network slice. The
purchaser also expects to, flexibly and independently, schedule and
maintain physical resources to support their own end-to-end
automation using both leased and self-constructed network resources.
2.4. Vertical dedicated network with OTN
Vertical industry slicing is an emerging category of network slicing
due to the high demand for private high-speed network interconnects
for industrial applications. In this scenario, the biggest challenge
is to implement differentiated optical network slices based on the
requirements from different industries. For example, in the
financial industry, to support high-frequency transactions, the slice
must ensure to provide the minimum latency along with the mechanism
for latency management. For the healthcare industry, online
diagnosis network and software capabilities to ensure the delivery of
HD video without frame loss. For bulk data migration in data
centers, the network needs to support on-demand, large-bandwidth
allocation. In each of the aforementioned vertical industry
scenarios, the bandwidth shall be adjusted as required to ensure
flexible and efficient network resource usage.
2.5. End-to-end network slicing
In an end-to-end network slicing scenario such as 5G network slicing
[TS.28.530-3GPP], an RFC 9543 network slice [RFC9543] provides the
required connectivity between other different segments of an end-to-
end network slice, such as the Radio Access Network (RAN) and the
Core Network (CN) segments, with a specific performance commitment.
An RFC 9543 network slice could be composed of network slices from
multiple technological and administrative domains. An RFC 9543
network slice can be realized by using or combining multiple
underlying OTN slices with OTN resources, e.g., ODU time slots or ODU
containers, to achieve end-to-end slicing across the transport
domain.
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3. Framework for OTN slicing
OTN slices may be abstracted differently depending on the requirement
contained in the configuration provided by the slice customer.
Whereas the customer requests an OTN slice to provide connectivity
between specified endpoints, an OTN slice can be abstracted as a set
of endpoint-to-endpoint links, with each link formed by an end-to-end
tunnel across the underlying OTN networks. The resources associated
with each link of the slice is reserved and commissioned in the
underlying physical network upon the completion of configuring the
OTN slice and all the links are active.
An OTN slice can also be abstracted as an abstract topology when the
customer requests the slice to share resources between multiple
endpoints and to use the resources on demand. The abstract topology
may consist of virtual nodes and virtual links, and their associated
resources are reserved but not commissioned across the underlying OTN
networks. The customer can later commission resources within the
slice dynamically using the NBI provided by the service provider. An
OTN slice could use abstract topology to connect endpoints with
shared resources to optimize the resource utilization, and
connections can be activated within the slice as needed.
It is worth noting that those means to abstract an OTN slice are
similar to the Virtual Network (VN) abstraction defined for higher-
level interfaces in [RFC8453], in which context a connectivity-based
slice corresponds to Type 1 VN and a resource-based slice corresponds
to Type 2 VN, respectively.
A particular resource in an OTN network, such as a port or link, may
be sliced with one of the two granularity levels:
* Link-based slicing, in which a link and its associated link
termination points (LTPs) are dedicatedly allocated to a
particular OTN slice.
* Tributary-slot based slicing, in which multiple OTN slices share
the same link by allocating different OTN tributary slots in
different granularities.
Furthermore, an OTN switch is typically fully non-blocking switching
at the lowest ODU container granularity, it is desirable to specify
just the total number of ODU containers in the lowest granularity
(e.g. ODU0), when configuring tributary-slot based slicing on links
and ports internal to an OTN network. In multi-domain OTN network
scenarios where separate OTN slices are created on each of the OTN
networks and are stitched at inter-domain OTN links, it is necessary
to specify matching tributary slots at the endpoints of the inter-
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domain links. In some real network scenarios, OTN network resources
including tributary slots are managed explicitly by network operators
for network maintenance considerations. Therefore, an OTN slice
controller shall support configuring an OTN slice with both options.
An OTN slice controller (OTN-SC) is a logical function responsible
for the life-cycle management of OTN slices instantiated within the
corresponding OTN network domains. The OTN-SC provides technology-
specific interfaces at its northbound (OTN-SC NBI) to allow a higher-
layer slice controller, such as an RFC 9543 network slice controller
(NSC) or an orchestrator, to request OTN slices with OTN-specific
requirements. The OTN-SC interfaces at the southbound using the
MDSC-to-PNC interface (MPI) with a Physical Network Controller (PNC)
or Multi-Domain Service Orchestrator (MDSC), as defined in the ACTN
control framework [RFC8453]. The logical function within the OTN-SC
is responsible for translating the OTN slice requests into concrete
slice realization which can be understood and provisioned at the
southbound by the PNC or MDSC.
The presence of OTN-SC provides multiple options for a high-level
slice controller or an orchestrator to configure and realize slicing
in OTN networks, depending on whether a customer's slice request is
technology agnostic or technology specific:
Option 1[opt.1]: An IETF NSC receives a technology-agnostic slice
request from the IETF NSC NBI and realizes full or part of the slice
in OTN networks directly through MPI provided by the PNC or MDSC.
The IETF NSC is responsible for mapping a technology-agnostic slicing
request into an OTN technology-specific realization. In this option,
the OTN-SC is not used.
Option 2[opt.2]: An IETF NSC receives a technology-agnostic slice
request from the IETF NSC NBI and delegates the request to the OTN-SC
through the OTN-SC NBI, which is OTN technology specific. The OTN-SC
in turn realizes the slice in single or multi domain OTN networks by
working with the underlying PNC or MDSC. In this option, the OTN-SC
is considered as a realization of IETF NSC, i.e., an NS realizer as
per [I-D.draft-contreras-teas-slice-controller-models], when the
underlying network is OTN. The OTN-SC is also a subordinate slice
controller of the RFC 9543 NSC, which is consistent with the
hierarchical control of slices specified by [RFC9543].
Option 3[opt.3]: An OTN-aware orchestrator may request an OTN
technology-specific slice with OTN-specific SLOs through the OTN-SC
NBI to the OTN-SC. The OTN-SC in turn realizes the slice in single
or multi domain OTN networks by working with the underlying PNC or
MDSC
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An OTN slice may be realized by using standard MPI interfaces,
control plane, network management system (NMS) or any other
proprietary interfaces as needed. Examples of such interfaces
include the abstract TE topology [RFC8795], TE tunnel
[I-D.ietf-teas-yang-te],L1VPN[RFC4847], or Netconf/YANG based
interfaces such as OpenConfig. Some of these interfaces, such as the
TE tunnel model, are suitable for creating connectivity-based OTN
slices which represent a slice as a set of TE tunnels, while other
interfaces such as the TE topology model are more suitable for
creating resource-based OTN slices which represent a slice as a
topology.
The OTN-SC NBI is a technology-specific interface that augments the
IETF NSC NBI, which is technology- agnostic.
Figure 2 illustrates the OTN slicing control hierarchy , the
positioning of the OTN slicing interfaces as well as the options for
OTN slice configuration.
+--------------------+
| Provider's User |
+--------|-----------+
| CMI
+-----------------------+--------------------------------+
| Orchestrator / E2E Slice Controller |
+------------+-----------------------------+-------------+
| | NSC-NBI
| +---------------------+-------------+
| | RFC 9543 Network Slice Controller |
| +-----+---------------+-------------+
| opt.3 | opt.2 | opt.1
| OTN-SC NBI |OTN-SC NBI |
+------------+-------------+--------+ |
| OTN-SC | |
+--------------------------+--------+ |
| MPI | MPI
+--------------------------+---------------+------------+
| PNC |
+--------------------------+----------------------------+
| SBI
+-----------+----------+
|OTN Physical Network |
+----------------------+
Figure 2: Positioning of OTN Slicing Interfaces
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OTN-SC functionalities may be recursive such that a higher-level OTN-
SC may designate the creation of OTN slices to a lower-level OTN-SC
in a recursive manner. This scenario may apply to the creation of
OTN slices in multi-domain OTN networks, where multiple domain-wide
OTN slices provisioned by lower-layer OTN-SCs are stitched to support
a multi-domain OTN slice provisioned by the higher-level OTN-SC.
Alternatively, the OTN-SC may interface with an MDSC, which in turn
interfaces with multiple PNCs through the MPI to realize OTN slices
in multi-domain OTN networks without OTN-SC recursion. Figure 3
illustrates both options for OTN slicing in multi-domain.
+-------------------+ +-------------------+
| OTN-SC | | OTN-SC |
+--------|----------+ +---|----------|----+
|MPI |OTN-SC NBI|
+--------|----------+ +---|----+ +---|----+
| MDSC | | OTN-SC | | OTN-SC |
+---|----------|----+ +---|----+ +---|----+
|MPI |MPI |MPI |MPI
+---|----+ +---|----+ +---|----+ +---|----+
| PNC | | PNC | | PNC | | PNC |
+--------+ +--------+ +--------+ +--------+
Multi-domain Option 1 Multi-domain Option 2
Figure 3: OTN-SC for multi-domain
OTN-SC functionalities are logically independent and may be deployed
in different combinations to cater to the realization needs. In
reference to the ACTN control framework [RFC8453], an OTN-SC may be
deployed
* as an independent network function;
* together with a Physical Network Controller (PNC) for single-
domain or with a Multi-Domain Service Orchestrator (MDSC)for
multi-domain;
* together with a higher-level network slice controller to support
end-to-end network slicing;
4. Realizing OTN Slices
[RFC9543] introduces a mechanism for an RFC 9543 network slice
controller to realize network slices by constructing Network Resource
Partitions (NRP). A NRP is a collection of resources identified in
the underlay network to facilitate the mapping of network slices onto
available network resources. An NRP is a scope view of a topology
and may be considered as a topology in its own right. Thus, in
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traffic-engineered (TE) networks including OTN, an NRP may be simply
represented as an abstract TE topology defined by [RFC8795]. For OTN
networks, An NRP may be represented as an abstract OTN topology
defined by [I-D.ietf-ccamp-otn-topo-yang].
The NRP may be used to address the scalability issues where there may
be considerable numbers of control and data plane states required to
be stored and programmed if network slices are mapped directly to the
underlay topology. NRP is internal to a network slice controller,
and use of NRPs is optional yet could benefit a network slice
realization in large-scale networks, including OTN networks.
For connectivity-based OTN slices, a connection within an OTN slice
is typically realized by an OTN tunnel in the underlay topology and
resources are reserved by the tunnel, thus use of NRP is optional in
this case.
For resource-based OTN slices, the OTN-SC may map an OTN slice
directly onto the underlay TE topology presented by the subtended
network controller (MDSC or PNC) without creating NRP topologies.
Due to the need for reserving resources, the OTN-SC needs to color
corresponding link resources of the underlay topology with a slice
identifier and maintain the coloring to keep track of the mapping of
OTN slices. The OTN-SC may push the colored topology to the
subtended MDSC or PNC using the MPI model defined in this draft.
Alternatively, an OTN slice may be mapped to a NRP as an overlay
abstract OTN TE topology on top of the underlay topology. The
corresponding link resources allocated to the slice is encapsulated
in and tracked by the abstract topology, and a given link or port in
the NRP topology represents resources that are reserved in the
underlay topology. Multiple OTN slices may be mapped to the same
NRP, and a single connectivity construct of the slice may be mapped
to only one NRP, as per [RFC9543]. The resources of an NRP topology
are reserved and shared by all the OTN slices mapped to this NRP, and
the NRP topology may be pushed directly to the subtended MDSC or PNC,
thus eliminating the need for link coloring if using the underlay
topology.
Figure 4 illustrates the relationship between OTN slices and NRP.
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/---------------/ | /---------------/
/ -- -- / | / -- -- /
/ |N1|---|N3| /---/ | / |N2| |N3| /
/ --\ -- / / | / -- -- /
/ \-- / / | / \ --/ /
/ |N2| / / | / |N4| /
/ Slice 1 -- / / | / Slice 2 -- /
/------------<--/ / | /-----------<---/
/ Slice 3 < / | <
/--------- <-<--/ | <
+-------------<-<--------------V-----------------<------------+
| /--<-<------------/ /-----<-----------/|
| / /--\ /--\ / / /--\ / |
| / |NE1 |---|NE2 | / / |NE2 | / |
| / \--/\ . \--/ / / \--/ / |
| / ..\ ........ / /. / |
| / . /--\ / . / /--\ /--\/ ./ |
| / .|NE4 | / . / |NE3 |---|NE4 | . |
| / . \--/ / . / \--/ . \--/ /. |
| / NRP Topology 1 / . / NRP Topology 2 / . |
| /------------.----/ . /-----------.-----/ . |
| ....... . . . |
| /------.----.-----------------/ . . |
| / /--\ . . /--\ / . . |
| / |NE1 |-.----v----|NE2 | / . . |
| / ---/\ . /\--/ / . . |
| / / \v /<........................ |
| / /-/\ \ /--\ / / . |
| / |NE3 |------|NE4 |/ / . |
| / \--/ ^ \--/ / . |
| / Underlay.OTN TE Topology / . |
| /-----------.-----------------/ . |
| .............................. OTN-SC |
+-------------------------------------------------------------+
| ^
|MPI |MPI
+----------------V--------------------------------------------+
| |
| OTN MDSC/PNC |
+-------------------------------------------------------------+
Figure 4: Mapping OTN Slices to NRP
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5. YANG Data Model for OTN Slicing Configuration
5.1. OTN Slicing YANG Model for MPI
5.1.1. MPI YANG Model Overview
For the configuration of connectivity-based OTN slices, existing
models such as the TE tunnel interface [I-D.ietf-teas-yang-te] may be
used and no addition is needed. This model is addressing the case
for configuring resource-based OTN slices, where the model permits to
reserve resources exploiting the common knowledge of an underlying
virtual topology between the OTN-SC and the subtended network
controller (MDSC or PNC). The slice is configured by marking
corresponding link resources on the TE topology received from the
underlying MDSC or PNC with a slice identifier and OTN-specific
resource requirements, e.g. the number of ODU time slots or the type/
number of ODU containers. The MDSC or PNC, based on the marked
resources by the OTN-SC, will update the underlying TE topology with
new TE link for each of the colored links to keep booked the reserved
OTN resources e.g. time slots or ODU containers.
5.1.2. MPI YANG Model Tree
module: ietf-otn-slice-mpi
augment /nw:networks/nw:network/nt:link/tet:te
/tet:te-link-attributes:
+--rw (otn-slice-granularity)?
+--:(link)
| +--rw slice-id? uint32
+--:(link-resource)
+--rw slices* [slice-id]
+--rw slice-id uint32
+--rw (technology)?
| +--:(otn)
| +--rw (slice-bandwidth)?
| +--:(containers)
| | +--rw odulist* [odu-type]
| | +--rw odu-type identityref
| | +--rw number? uint16
| +--:(time-slots)
| +--rw otn-ts-num? uint32
+--ro sliced-link-ref?
-> ../../../../../nt:link/link-id
Figure 5: OTN slicing MPI tree diagram
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5.1.3. MPI YANG Code
<CODE BEGINS> file "ietf-otn-slice-mpi@2022-10-12.yang"
module ietf-otn-slice-mpi {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-otn-slice-mpi";
prefix "otns-mpi";
import ietf-network {
prefix "nw";
reference
"RFC 8345: A YANG Data Model for Network Topologies";
}
import ietf-network-topology {
prefix "nt";
reference
"RFC 8345: A YANG Data Model for Network Topologies";
}
import ietf-te-topology {
prefix "tet";
reference
"RFC8795: YANG Data Model for Traffic Engineering
(TE) Topologies";
}
import ietf-otn-topology {
prefix "otnt";
reference
"I-D.ietf-ccamp-otn-topo-yang: A YANG Data Model
for Optical Transport Network Topology";
}
import ietf-layer1-types {
prefix "l1-types";
reference
"I-D.ietf-ccamp-layer1-types: A YANG Data Model
for Layer 1 Types";
}
organization
"IETF CCAMP Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/ccamp/>
WG List: <mailto:ccamp@ietf.org>
Editor: Haomian Zheng
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<mailto:zhenghaomian@huawei.com>
Editor: Italo Busi
<mailto:italo.busi@huawei.com>
Editor: Aihua Guo
<mailto:aihuaguo.ietf@gmail.com>
Editor: Sergio Belotti
<mailto:sergio.belotti@nokia.com>";
description
"This module defines a YANG data model for network slice
realization in Optical Transport Networks (OTN).
The model fully conforms to the Network Management Datastore
Architecture (NMDA).
Copyright (c) 2022 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Revised BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see the
RFC itself for full legal notices.";
revision "2022-10-12" {
description
"Latest revision of MPI YANG model for OTN slicing.";
reference
"draft-ietf-ccamp-yang-otn-slicing-03: Framework and Data
Model for OTN Network Slicing";
}
/*
* Groupings
*/
grouping otn-link-slice-profile {
description
"Profile of an OTN link slice.";
choice otn-slice-granularity {
default "link";
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description
"Link slice granularity.";
case link {
leaf slice-id {
type uint32;
description
"Slice identifier";
}
}
case link-resource {
list slices {
key slice-id;
description
"List of slices.";
leaf slice-id {
type uint32;
description
"Slice identifier";
}
choice technology {
description
"Data plane technology types.";
case otn {
choice slice-bandwidth {
description
"Bandwidth specification for OTN slices.";
case containers {
uses l1-types:otn-link-bandwidth;
}
case time-slots {
leaf otn-ts-num {
type uint32;
description
"Number of OTN tributary slots allocated
for the slice.";
}
}
}
}
}
leaf sliced-link-ref {
type leafref {
path "../../../../../nt:link/nt:link-id";
}
config false;
description
"Relative reference to virtual links generated from
this TE link.";
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}
}
}
}
}
/*
* Augments
*/
augment "/nw:networks/nw:network/nt:link/tet:te/"
+ "tet:te-link-attributes" {
when "../../../nw:network-types/tet:te-topology/"
+ "otnt:otn-topology" {
description
"Augmentation parameters apply only for networks with
OTN topology type.";
}
description
"Augment OTN TE link attributes with slicing profile.";
uses otn-link-slice-profile;
}
}
<CODE ENDS>
Figure 6: OTN slicing MPI YANG model
5.2. OTN Slicing YANG Model for OTN-SC NBI
5.2.1. NBI YANG Model Overview
The YANG model for OTN-SC NBI is OTN-technology specific, but shares
many common constructs and attributes with the common network slicing
YANG model defined in [I-D.ietf-teas-ietf-network-slice-nbi-yang].
Furthermore, the OTN-SC NBI YANG is expected to support both
connectivity-based and resource-based slice configuration, which is
likely a common requirement for supporting slicing at other transport
network layers, e.g. WDM or MPLS(-TP).
The OTN slicing model augments the common network slicing YANG model
by extending OTN technology-specific SLO and SLE attributes which can
be requested by OTN-aware customers and allows the customer to
specify desired OTN signal quality. These attributes include:
* The performance objective for Optical Data Unit (ODU) containers