OPSAWG O. Gonzalez de Dios, Ed.
Internet-Draft S. Barguil
Intended status: Standards Track Telefonica
Expires: October 4, 2020 Q. Wu
Huawei
M. Boucadair
Orange
April 2, 2020
A YANG Model for User-Network Interface (UNI) Topologies
draft-ogondio-opsawg-uni-topology-01
Abstract
This document defines a YANG data model for representing an abstract
view of the Service Provider network topology containing the points
from which its services can be attached (e.g., basic connectivity,
VPN, SDWAN). The data model augments the 'ietf-network' data model
by adding the concept of service-attachment-points. The service-
attachment-points are an abstraction of the points to which network
services (such as L3 VPN or L2 VPN) can be attached.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on October 4, 2020.
Copyright Notice
Copyright (c) 2020 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
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publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. UNI Topology Model Usage . . . . . . . . . . . . . . . . . . 4
3. YANG Module Structure Details . . . . . . . . . . . . . . . . 5
4. YANG module . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. Implementation Status . . . . . . . . . . . . . . . . . . . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.1. Normative References . . . . . . . . . . . . . . . . . . 10
9.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
The User-Network Interface (UNI) is an important architectural
concept in many implementations and deployments of services such as
VPNs or managed VoIP services.
This document defines a YANG data model for representing, managing
and controlling the User Network Interface (UNI) topology. The data
model augments the 'ietf-network' module [RFC8345] by adding the
concept of service attachment points. The service attachment points
are abstraction of the points where network services such as L3 VPNs
or L2 VPNs can be attached.
This document does not make any assumption about the service provided
by the network to the users. VPN service is used for illustration
purposes.
In the context of Software-Defined Networking (SDN) [RFC7149]
[RFC7426], the defined YANG data model in this document can be used
to exchange information between control elements, so as to support
VPN service provision and resource management discussed in
[I-D.ietf-opsawg-l3sm-l3nm]. Through this data model, the service
orchestration layer can learn the capability and available
endpoint(s) of interconnection resource of the underlying network.
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The service orchestration layer can determine which endpoint of
interconnection to add to L2VPN or L3VPN service. With the help of
other data models (e.g., L3SM model [RFC8299] and L3NM model) and
mechanism, hierarchical control elements could determine the
feasibility of an end-to-end path and to derive the sequence of
domains and the points of interconnection to use.
This document explains the scope and purpose of a uni topology model
and its relation with the service models and describes how it can be
used by a network operator. The document also shows how the topology
and service models fit together.
The YANG data model in this document conforms to the Network
Management Datastore Architecture (NMDA) [RFC8342].
1.1. Terminology
This document assumes that the reader is familiar with the contents
of [RFC6241], [RFC7950] and [RFC8309]. The document uses
terminologies from those documents. Tree diagrams used in this
document follow the notation defined in [RFC8340].
This document uses the following terms:
Service Provider (SP): The organization (usually a commercial
undertaking) responsible for operating the network that offers a
service (e.g. a VPN) to customers.
Customer Edge (CE): An equipment that is dedicated to a particular
customer and is directly connected to one or more PE devices via
attachment circuits. A CE is usually located at the customer
premises, and is usually dedicated to a single service (e.g VPN),
although it may support multiple VPNs if each one has separate
attachment circuits. A CE device can be a router, bridge, switch,
etc.
Provider Edge (PE): An equipment owned and managed by the SP that
can support multiple services (e.g. VPNs) for different
customers, and is directly connected to one or more CE devices via
attachment circuits. A PE is usually located at an SP point of
presence (PoP).
Attachment point(AP): Describe a service's end point characteristics
and its reference to a Termination Point (TP) of the Provider Edge
(PE) Node; used as service access point for VPN service, for
example.
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1.2. Requirements Language
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.
2. UNI Topology Model Usage
Management operations of a service provider network can be automated
using a variety of means such as interfaces based on YANG modules.
Considering the architecture depicted in Figure 1, the goal is to be
able to show via a YANG-based interface an abstracted network view
from the network controller to the service orchestration layer.
+---------------+
| Customer |
+---------------+
Customer Service Models |
|
+-----------------+
| Service |
| Orchestration |
+-----------------+
Service Network Models | | UNI Topology Model
| |
+-----------------+
| Network |
| Controller |
+-------|----------+
|
+------------------------------------------------+
Network
Figure 1
The service orchestration layer does not need to know about the
internals of the network. Hence, the abstraction's need is to be
able to get the set of nodes, and the attachment points associated
with the nodes from which network services can be grafted
(delivered). Let us consider the example of a typical Service
Provider network (Figure 2), with PE and P nodes. The Service
orchestration layer would see a set of PEs, and a set of client-
facing ports to which CEs can be connected (or are actually
connected). Service orchestration layer will have also access to a
set of Customer Service Model, e.g., a L3SM or L2SM data model in the
customer-facing interface and a set of Network models, e.g., L3NM and
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Network topology data models. In this use case, it is assumed that
the network controller is unaware of what happens beyond the PEs
towards the CEs; it is only responsible for the management and
control of the network between PEs.
*---|-|---* *---|-|---*
-| PE | -| PE |-
*----|----* *----|----*
\ /
*----|----*
| P |
*----|----*
/ \
*----|----* *----|----*
-| PE | | PE |-
*---|-|---* *-|-|-|-|-*
Figure 2
How the abstracted view of the network controller can look like is
depicted in Figure 3.
+---|-|---+ +---|-|---+
-| PE |---------| PE |-
+----|----+ +----|----+
| |
+----|----+ +----|----+
-| PE |---------| PE |-
+---|-|---+ +-|-|-|-|-+
Figure 3
3. YANG Module Structure Details
The abstract (base) network data model is defined in the 'ietf-
network' module of [RFC8345].
The UNI-topology builds on the network data model defined in the
'ietf-network' module [RFC8345], augmenting the nodes with service-
attachment points, which anchor the links and are contained in nodes.
The structure of the 'ietf-uni-topology' module is shown in Figure 4.
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module: ietf-uni-topology
augment /nw:networks/nw:network/nw:node:
+--rw service-attachment-point* [attachment-id]
+--rw attachment-id nt:tp-id
+--rw type? identityref
+--rw admin-status? boolean
+--rw oper-status? boolean
+--rw encapsulation-type? string
Figure 4
4. YANG module
This module imports types from [RFC8343] and [RFC8345].
<CODE BEGINS> file "ietf-uni-topology@2020-04-02.yang"
module ietf-uni-topology {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-uni-topology";
prefix uni;
import ietf-interfaces {
prefix if;
reference
"RFC 8343: A YANG Data Model for Interface Management";
}
import ietf-network-topology {
prefix nt;
reference
"Section 6.2 of RFC 8345: A YANG Data Model for Network
Topologies";
}
import ietf-network {
prefix nw;
reference
"Section 6.1 of RFC 8345: A YANG Data Model for Network
Topologies";
}
organization
"IETF OPSA (Operations and Management Area) Working Group ";
contact
" Editor: Oscar Gonzalez de Dios
<mailto:oscar.gonzalezdedios@telefonica.com>
Editor: Samier Barguil
<mailto:alejandro.aguado_martin@nokia.com>
Editor: Qin Wu
<mailto:victor.lopezalvarez@telefonica.com>
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Editor: Mohamed Boucadair
<mailto:daniel.voyer@bell.ca>
";
description
"This YANG module defines a model for representing, managing
and controlling the User Network Interface (UNI) topology.
Copyright (c) 2020 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
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
for full legal notices.";
revision 2020-04-02 {
description
"Initial version";
reference
"RFC XXXX: A YANG Model for User-Network Interface (UNI)
Topologies";
}
grouping uni-information-group {
description
"User-Network Interface Information";
list service-attachment-point {
key "attachment-id";
description
"The service attachment points are abstraction of
the points where network services such as L3 VPNs
or L2 VPNs can be attached.";
leaf attachment-id {
type nt:tp-id;
description
"Name of the interface";
}
leaf type {
type identityref {
base if:interface-type;
}
config false;
description
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"The type of the interface.";
reference
"RFC 8343: A YANG Data Model for Interface Management";
}
leaf admin-status {
type boolean;
description
"Administrative Status UP/DOWN";
}
leaf oper-status {
type boolean;
description
"Operational Status UP/DOWN";
}
leaf encapsulation-type {
type string;
description
"Encapsulation type. By default, the
encapsulation type is set to 'untagged'.";
}
}
}
augment "/nw:networks/nw:network/nw:network-types" {
description
"Introduces new network type for UNI Unicast topology";
container uni-topology {
presence "indicates UNI Unicast topology";
description
"The presence of the container node indicates UNI
topology";
}
}
augment "/nw:networks/nw:network/nw:node" {
description
"Parameters for the service edge point level.";
uses uni-information-group;
}
}
<CODE ENDS>
Figure 5
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5. IANA Considerations
This document registers the following namespace URI in the "ns"
subregistry within the "IETF XML Registry" [RFC3688]:
--------------------------------------------------------------------
URI: urn:ietf:params:xml:ns:yang:ietf-uni-topology
Registrant Contact: The IESG.
XML: N/A, the requested URI is an XML namespace.
--------------------------------------------------------------------
This document registers the following YANG module in the YANG Module
Names registry [RFC6020] within the "YANG Parameters" registry:
--------------------------------------------------------------------
name: ietf-uni-topology
namespace: urn:ietf:params:xml:ns:yang:ietf-uni-topology
maintained by IANA: N
prefix: uni
reference: RFC XXXX
--------------------------------------------------------------------
6. Security Considerations
The YANG module specified in this document defines a schema for data
that is designed to be accessed via network management protocols such
as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer
is the secure transport layer, and the mandatory-to-implement secure
transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer
is HTTPS, and the mandatory-to-implement secure transport is TLS
[RFC8446].
The Configuration Access Control Model (NACM) [RFC8341] provides the
means to restrict access for particular NETCONF or RESTCONF users to
a preconfigured subset of all available NETCONF or RESTCONF protocol
operations and content.
There are a number of data nodes defined in this YANG module that are
writable/creatable/deletable (i.e., config true, which is the
default). These data nodes may be considered sensitive or vulnerable
in some network environments. Write operations (e.g., edit-config)
to these data nodes without proper protection can have a negative
effect on network operations. These are the subtrees and data nodes
and their sensitivity/vulnerability:
o /nw:networks/nw:network/nw:node/uni:service-attachment-point/
uni:attachment-id
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This subtree specifies the configurations of the nodes in a UNI
network topology. Unexpected changes to this subtree could lead
to service disruption and/or network misbehavior.
Some of the readable data nodes in this YANG module may be considered
sensitive or vulnerable in some network environments. It is thus
important to control read access (e.g., via get, get-config, or
notification) to these data nodes. These are the subtrees and data
nodes and their sensitivity/vulnerability:
o /nw:networks/nw:network/nw:node/uni:service-attachment-point
Unauthorized access to this subtree can disclose the operational
state information of the nodes in a UNI topology.
7. Implementation Status
This section will be used to track the status of the implementations
of the model. It is aimed at being removed if the document becomes
RFC.
8. Acknowledgements
Thanks to Adrian Farrell and Daniel King for the suggestions on the
names.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
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[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<https://www.rfc-editor.org/info/rfc6242>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
<https://www.rfc-editor.org/info/rfc8341>.
[RFC8345] Clemm, A., Medved, J., Varga, R., Bahadur, N.,
Ananthakrishnan, H., and X. Liu, "A YANG Data Model for
Network Topologies", RFC 8345, DOI 10.17487/RFC8345, March
2018, <https://www.rfc-editor.org/info/rfc8345>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
9.2. Informative References
[I-D.ietf-opsawg-l3sm-l3nm]
Barguil, S., Dios, O., Boucadair, M., Munoz, L., and A.
Aguado, "A Layer 3 VPN Network YANG Model", draft-ietf-
opsawg-l3sm-l3nm-02 (work in progress), March 2020.
[RFC7149] Boucadair, M. and C. Jacquenet, "Software-Defined
Networking: A Perspective from within a Service Provider
Environment", RFC 7149, DOI 10.17487/RFC7149, March 2014,
<https://www.rfc-editor.org/info/rfc7149>.
[RFC7426] Haleplidis, E., Ed., Pentikousis, K., Ed., Denazis, S.,
Hadi Salim, J., Meyer, D., and O. Koufopavlou, "Software-
Defined Networking (SDN): Layers and Architecture
Terminology", RFC 7426, DOI 10.17487/RFC7426, January
2015, <https://www.rfc-editor.org/info/rfc7426>.
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[RFC8299] Wu, Q., Ed., Litkowski, S., Tomotaki, L., and K. Ogaki,
"YANG Data Model for L3VPN Service Delivery", RFC 8299,
DOI 10.17487/RFC8299, January 2018,
<https://www.rfc-editor.org/info/rfc8299>.
[RFC8309] Wu, Q., Liu, W., and A. Farrel, "Service Models
Explained", RFC 8309, DOI 10.17487/RFC8309, January 2018,
<https://www.rfc-editor.org/info/rfc8309>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
[RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "Network Management Datastore Architecture
(NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
<https://www.rfc-editor.org/info/rfc8342>.
[RFC8343] Bjorklund, M., "A YANG Data Model for Interface
Management", RFC 8343, DOI 10.17487/RFC8343, March 2018,
<https://www.rfc-editor.org/info/rfc8343>.
Authors' Addresses
Oscar Gonzalez de Dios (editor)
Telefonica
Madrid
ES
Email: oscar.gonzalezdedios@telefonica.com
Samier Barguil
Telefonica
Madrid
ES
Email: samier.barguilgiraldo.ext@telefonica.com
Qin Wu
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: bill.wu@huawei.com
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Mohamed Boucadair
Orange
Caen
France
Email: mohamed.boucadair@orange.com
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