OPSAWG O. Gonzalez de Dios, Ed.
Internet-Draft S. Barguil
Intended status: Standards Track Telefonica
Expires: May 22, 2020 Q. Wu
Huawei
M. Boucadair
Orange
November 19, 2019
A YANG Model for User-Network Interface (UNI) Topologies
draft-ogondio-opsawg-uni-topology-00
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 ietf-network 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 VPNs or L2 VPNs) can be attached.
Status of This Memo
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This Internet-Draft will expire on May 22, 2020.
Copyright Notice
Copyright (c) 2019 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
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
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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 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 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 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 descibes 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], [RFC8309], and [RFC8453] and 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 sertice'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 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 abstration'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 requested. 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 models in the customer-facing interface and a set of
Network models,e.g., L3NM model and Network topology models. In this
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use case, it is assumed that the network controller is unaware of
what happens beyond the PEs towards the CEs and responsible for the
management and control of the network between PEs.
*---|-|---* *---|-|---*
-| PE | -| PE |-
*----|----* *----|----*
\ /
*----|----*
| P |
*----|----*
/ \
*----|----* *----|----*
-| PE | | PE |-
*---|-|---* *-|-|-|-|-*
Figure 2
Hence, the abstracted view of the network controller can look like
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 . The notation syntax follows the syntax used in [RFC8340].
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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@2019-11-19.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
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<mailto:victor.lopezalvarez@telefonica.com>
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) 2019 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.
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 (RFC 2119) (RFC 8174) when, and only when,
they appear in all capitals, as shown here.";
revision 2019-11-19 {
description
"Initial version";
reference
"draft-ogondio-opsawg-uni-topology";
}
grouping uni-information-group {
list service-attachment-point {
key "attachment-id";
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.
When an interface entry is created, a server MAY
initialize the type leaf with a valid value, e.g., if it
is possible to derive the type from the name of the
interface.
If a client tries to set the type of an interface to a
value that can never be used by the system, e.g., if the
type is not supported or if the type does not match the
name of the interface, the server MUST reject the request.
A NETCONF server MUST reply with an rpc-error with the
error-tag 'invalid-value' in this case.";
reference
"RFC 2863: The Interfaces Group MIB - ifType";
}
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'.";
}
description
"service-edge-point refers to the available ports on
the network.";
}
description
"UNI Information";
}
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 URIs in 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]:
--------------------------------------------------------------------
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
[RFC5246].
The NETCONF access control model [RFC6536] 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>.
[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>.
[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>.
[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>.
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[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>.
[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>.
9.2. Informative References
[I-D.ietf-opsawg-l3sm-l3nm]
Aguado, A., Dios, O., Lopezalvarez, V., Voyer, D., and L.
Munoz, "Layer 3 VPN Network Model", draft-ietf-opsawg-
l3sm-l3nm-00 (work in progress), October 2019.
[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>.
[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>.
[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>.
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[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>.
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
Mohamed Boucadair
Orange
Caen
France
Email: mohamed.boucadair@orange.com
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