CCAMP Working Group Haomian Zheng
Internet Draft Italo Busi
Intended status: Standard Track Huawei Technologies
Aihua Guo
Futurewei Technologies
Victor Lopez
Telefonica I+D/GCTO
Expires: August 2021 February 22, 2021
Framework and Data Model for OTN Network Slicing
draft-zheng-ccamp-yang-otn-slicing-01
Abstract
The requirement of slicing network resource 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 a
YANG data model augmentation of the OTN topology model. Additional
YANG data model augmentations will be defined in a future version of
this draft.
Status of this Memo
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Table of Contents
1. Introduction...................................................3
2. Use Cases for OTN Network Slicing..............................3
2.1. Leased Line Services with OTN.............................3
2.2. Co-construction and Sharing...............................3
2.3. Wholesale of optical resources............................4
2.4. Vertical dedicated network with OTN.......................4
3. Framework for OTN slicing......................................5
4. YANG Data Model for OTN Slicing Configuration..................7
4.1. OTN Slicing YANG Model for MPI............................7
4.1.1. MPI YANG Model Overview..............................7
4.1.2. MPI YANG Model Tree..................................7
4.1.3. MPI YANG Code........................................7
4.2. OTN Slicing YANG Model for OTN-SC NBI....................11
5. Manageability Considerations..................................11
6. Security Considerations.......................................11
7. IANA Considerations...........................................11
8. References....................................................12
8.1. Normative References.....................................12
8.2. Informative References...................................12
Acknowledgments..................................................12
Contributors' Addresses..........................................12
Authors' Addresses...............................................13
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1. Introduction
The requirement of slicing network resource 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 a
YANG data model augmentation of the OTN topology model. Additional
YANG data model augmentations will be defined in a future version of
this draft.
2. Use Cases for OTN Network Slicing
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 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
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system to provision services remotely. In this scenario, different
founders' network resources need to be automatically (associated)
divided, isolated, and visualized. In addition, all founders 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 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, in a flexible and independent
manner, 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
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vertical industry scenarios, the bandwidth shall be adjusted as
required to ensure flexible and efficient network resource usage.
3. Framework for OTN slicing
An OTN slice is a collection of OTN network resources that are used
to establish a logically dedicated OTN virtual network over one or
more OTN networks. For example, the bandwidth of an OTN slice is
described in terms of the number/type of OTN time slots; the labels
may be specified as OTN tributary slots and/or tributary ports to
allow slice users to interconnect devices with matching
specifications.
The relationship between an OTN slice and an IETF network slice [I-D.
teas-transport-network-slice-yang] is for further discussions.
To support the configuration of OTN slices, an OTN slice controller
(OTN-SC) can be deployed either outside or within the SDN controller.
In the former case, the OTN-SC translates an OTN slice configuration
request into a TE topology configuration or a set of TE tunnel
configurations, and instantiate it by using the TE topology [RFC8795]
or TE tunnel [I-D.ietf-teas-yang-te] interfaces at the MPI (MDSC-to-
PNC Interface), as defined in the ACTN framework [RFC8453].
In the latter case, an Orchestrator or an end-to-end slice controller
may request OTN slices directly through the OTN slicing interface
provided by the OTN-SC. A higher-level OTN-SC may also designate the
creation of OTN slices to a lower-level OTN-SC in a recursive manner.
Figure 1 illustrates the OTN slicing control hierarchy and the
positioning of the OTN slicing interfaces.
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+--------------------+
| Provider's User |
+--------|-----------+
|CMI
+----------------------+---------------------------+
| Orchestrator / E2E Slice Controller |
+-----------+------------------------------+-------+
|OTN-SC NBI |
| |
+-----------+---------+ OTN-SC NBI |OTN-SC NBI
| OTN-SC +---------------+ |
+-----------+---------+ | |
|MPI | |
+------------|-------------------------|----|--------+
| SDN | +-------+----+-------+|
| Controller | | OTN-SC ||
| | +-------+------------+|
| | |Internal API |
|+-----------+-------------------------+------------+|
|| PNC/MDSC ||
|+-----------------------+--------------------------+|
+------------------------|---------------------------+
|SBI
+-----------+----------+
|OTN Physical Network |
+----------------------+
Figure 1 - Positioning of OTN Slicing Interfaces
A particular OTN network resource, such as a port or link, may be
sliced in two modes:
o Link-based slicing, where a link and its associated link
termination points (LTPs) are dedicatedly allocated to a
particular OTN network slice.
o Tributary-slot based slicing, where multiple OTN network slices
share the same link by allocating different OTN tributary slots in
different granularities.
Additionally, since OTN tributary slots are usually switched
unconstrained at every node within an OTN network, it is unimportant
to which exact tributary slot(s) an OTN slice is allocated, but
rather mattered is the number and type of the tributary slots.
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4. YANG Data Model for OTN Slicing Configuration
4.1. OTN Slicing YANG Model for MPI
4.1.1. MPI YANG Model Overview
An SDN controller (PNC or MDSC) exposes to the OTN-SC set of
available resources for OTN slicing in the form of an abstract TE
topology. When the OTN-SC receives slice configuration from the NBI,
it translates the configuration into a coloring scheme on the
abstract TE topology, by marking corresponding link resources on the
TE topology received from the SDN controller with a slice identifier
and OTN-specific resource requirements, e.g. the number of ODU time
slots. When the SDN controller receives the slice configuration, it
shall create a new virtual TE link for each of the colored links to
hold the reserved OTN time slots for time slot-based slicing. These
resultant virtual links are then included in the TE topology
advertisement to the OTN-SC.
4.1.2. MPI YANG Model Tree
module: ietf-otn-slice
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 otn-ts-num? uint32
+--ro sliced-link-ref? ->
../../../../../nt:link/link-id
Figure 2 - OTN network slicing tree diagram
4.1.3. MPI YANG Code
<CODE BEGINS>file "ietf-otn-slice@2021-02-22.yang"
module ietf-otn-slice {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-otn-slice";
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prefix "otnslice";
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 "otntopo";
reference
"I-D.ietf-ccamp-otn-topo-yang: A YANG Data Model
for Optical Transport Network Topology";
}
organization
"IETF CCAMP Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/ccamp/>
WG List: <mailto:ccamp@ietf.org>
Editor: Haomian Zheng
<mailto:zhenghaomian@huawei.com>
Editor: Italo Busi
<mailto:italo.busi@huawei.com>
Editor: Aihua Guo
<mailto:aihuaguo.ietf@gmail.com>
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Editor: Victor Lopez
<mailto:victor.lopezalvarez@telefonica.com>";
description
"This module defines a YANG data model to configure an OTN
network slice realization.
The model fully conforms to the Network Management Datastore
Architecture (NMDA).
Copyright (c) 2021 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 Simplified 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 "2021-02-22" {
description
"Initial Version";
reference
"draft-zheng-ccamp-yang-otn-slicing-01: Framework and Data
Model for OTN Network Slicing";
}
/*
* Groupings
*/
grouping otn-link-slice-profile {
choice otn-slice-granularity {
default link;
case link {
leaf slice-id {
type uint32;
description
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"Slice identifier";
}
}
case link-resource {
list slices {
key slice-id;
description
"List of slices.";
leaf slice-id {
type uint32;
description
"Slice identifier";
}
choice technology {
case otn {
leaf otn-ts-num {
type uint32;
description
"Number of OTN tributary slots allocated for the
slice.";
}
}
}
leaf sliced-link-ref {
config false;
type leafref {
path "../../../../../nt:link/nt:link-id";
}
description
"Relative reference to virtual links generated from
this TE link.";
}
}
}
}
}
/*
* Augments
*/
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augment "/nw:networks/nw:network/nt:link/tet:te/"
+ "tet:te-link-attributes" {
when "../../../nw:network-types/tet:te-topology/"
+ "otntopo: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 3 - OTN network slicing YANG model
4.2. OTN Slicing YANG Model for OTN-SC NBI
TBD.
5. Manageability Considerations
To ensure the security and controllability of physical resource
isolation, slice-based independent operation and management are
required to achieve management isolation.
Each optical slice typically requires dedicated accounts,
permissions, and resources for independent access and O&M. This
mechanism is to guarantee the information isolation among slice
tenants and to avoid resource conflicts. The access to slice
management functions will only be permitted after successful security
checks.
6. Security Considerations
<Add any security considerations>
7. IANA Considerations
<Add any IANA considerations>
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8. References
8.1. Normative References
[RFC8453] Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for
Abstraction and Control of TE Networks (ACTN)", RFC 8453,
DOI 10.17487/RFC8453, August 2018 <https://www.rfc-
editor.org/info/rfc8453>.
[RFC8795] Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and
O. Gonzalez de Dios, "YANG Data Model for Traffic
Engineering (TE) Topologies", RFC 8795, DOI
10.17487/RFC8795, August 2020, <https://www.rfc-
editor.org/info/rfc8795>.
[I-D. teas-transport-network-slice-yang] Liu, X., Tantsura J.,
Bryskin I., Contreras L., Wu Q., Belotti S., and Rokui R.,
"Transport Network Slice YANG Data Model", draft-liu-teas-
transport-network-slice-yang-01 (work in progress), July
2020.
[I-D.ietf-teas-yang-te] Saad, T., Gandhi, R., Liu, X., Beeram, V.,
and I. Bryskin, "A YANG Data Model for Traffic Engineering
Tunnels and Interfaces", draft-ietf-teas-yang-te-22 (work
in progress), November 2019.
8.2. Informative References
TBD
Acknowledgments
This document was prepared using 2-Word-v2.0.template.dot.
Contributors' Addresses
Henry Yu
Huawei Technologies Canada
Email: henry.yu@huawei.com
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Authors' Addresses
Haomian Zheng
Huawei Technologies
H1, Xiliu Beipo Village, Songshan Lake,
Dongguan,
China
Email: zhenghaomian@huawei.com
Italo Busi
Huawei Technologies
Email: italo.busi@huawei.com
Aihua Guo
Futurewei Technologies
Email: aihuaguo.ietf@gmail.com
Victor Lopez
Telefonica I+D/GCTO
Distrito Telefonica
E-28050 Madrid, Spain
Email: victor.lopezalvarez@telefonica.com
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