Internet DRAFT - draft-busi-teas-te-topology-profiles
draft-busi-teas-te-topology-profiles
TEAS Working Group I. Busi
Internet-Draft Huawei
Intended status: Informational X. Liu
Expires: 1 August 2024 Alef Edge
I. Bryskin
Individual
T. Saad
Cisco Systems Inc
O. Gonzalez de Dios
Telefonica
29 January 2024
Profiles for Traffic Engineering (TE) Topology Data Model and
Applicability to non-TE Use Cases
draft-busi-teas-te-topology-profiles-08
Abstract
This document describes how profiles of the Traffic Engineering (TE)
Topology Model, defined in RFC8795, can be used to address
applications beyond "Traffic Engineering".
Status of This Memo
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This Internet-Draft will expire on 1 August 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.
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Examples of non-TE scenarios . . . . . . . . . . . . . . . . 3
2.1. UNI Topology Discovery . . . . . . . . . . . . . . . . . 3
2.2. Administrative and Operational status management . . . . 5
2.3. Overlay and Underlay non-TE Topologies . . . . . . . . . 6
2.4. Nodes with switching limitations . . . . . . . . . . . . 7
3. Technology-specific augmentations . . . . . . . . . . . . . . 8
3.1. Multi-inheritance . . . . . . . . . . . . . . . . . . . . 10
3.2. Example (Link augmentation) . . . . . . . . . . . . . . . 11
4. Implemented profiles . . . . . . . . . . . . . . . . . . . . 12
5. Security Considerations . . . . . . . . . . . . . . . . . . . 13
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 13
References . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Normative References . . . . . . . . . . . . . . . . . . . . . 13
Informative References . . . . . . . . . . . . . . . . . . . . 14
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
There are many network scenarios being discussed in various IETF
Working Groups (WGs) that are not classified as "Traffic Engineering"
but can be addressed by a sub-set (profile) of the Traffic
Engineering (TE) Topology YANG data model, defined in [RFC8795].
Traffic Engineering (TE) is defined in [I-D.ietf-teas-rfc3272bis] as
aspects of Internet network engineering that deal with the issues of
performance evaluation and performance optimization of operational IP
networks. TE encompasses the application of technology and
scientific principles to the measurement, characterization, modeling,
and control of Internet traffic.
The TE Topology Model is augmenting the Network Topology Model
defined in [RFC8345] with generic and technology-agnostic features
that some are strictly applicable to TE networks, while others
applicable to both TE and non-TE networks.
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Examples of such features that are applicable to both TE and non-TE
networks are: inter-domain link discovery (plug-id), geo-
localization, and admin/operational status.
It is also worth noting that the TE Topology Model is quite an
extensive and comprehensive model in which most features are
optional. Therefore, even though the full model appears to be
complex, at the first glance, a sub-set of the model (profile) can be
used to address specific scenarios, e.g. suitable also to non-TE use
cases.
The implementation of such TE Topology profiles can simplify and
expedite adoption of the full TE topology YANG data model, and allow
for its reuse even for non-TE use case. The key question being
whether all or some of the attributes defined in the TE Topology
Model are needed to address a given network scenario.
Section 2 provides examples where profiles of the TE Topology Model
can be used to address some generic use cases applicable to both TE
and non-TE technologies.
2. Examples of non-TE scenarios
2.1. UNI Topology Discovery
UNI Topology Discovery is independent from whether the network is TE
or non-TE.
The TE Topology Model supports inter-domain link discovery (including
but not being limited to UNI link discovery) using the plug-id
attribute. This solution is quite generic and does not require the
network to be a TE network.
The following profile of the TE Topology model can be used for the
UNI Topology Discovery:
module: ietf-te-topology
augment /nw:networks/nw:network/nw:network-types:
+--rw te-topology!
augment /nw:networks/nw:network/nw:node/nt:termination-point:
+--rw te-tp-id? te-types:te-tp-id
+--rw te!
+--rw admin-status?
| te-types:te-admin-status
+--rw inter-domain-plug-id? binary
+--ro oper-status? te-types:te-oper-status
Figure 1: UNI Topology
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The profile data model shown in Figure 1 can be used to discover TE
and non TE UNIs as well as to discover UNIs for TE or non TE
networks.
Such a UNI TE Topology profile model can also be used with
technology-specific UNI augmentations, as described in section 3.
For example, in [I-D.ietf-ccamp-eth-client-te-topo-yang], the eth-svc
container is defined to represent the capabilities of the Termination
Point (TP) to be configured as an Ethernet client UNI, together with
the Ethernet classification and VLAN operations supported by that TP.
The [I-D.ietf-ccamp-otn-topo-yang] provides another example, where:
* the client-svc container is defined to represent the capabilities
of the TP to be configured as an transparent client UNI (e.g.,
STM-N, Fiber Channel or transparent Ethernet);
* the OTN technology-specific Link Termination Point (LTP)
augmentations are defined to represent the capabilities of the TP
to be configured as an OTN UNI, together with the information
about OTN label and bandwidth availability at the OTN UNI.
For example, the UNI TE Topology profile can be used to model
features defined in [I-D.ogondio-opsawg-uni-topology]:
* The inter-domain-plug-id attribute would provide the same
information as the attachment-id attribute defined in
[I-D.ogondio-opsawg-uni-topology];
* The admin-status and oper-status that exists in this TE topology
profile can provide the same information as the admin-status and
oper-status attributes defined in
[I-D.ogondio-opsawg-uni-topology].
Following the same approach in
[I-D.ietf-ccamp-eth-client-te-topo-yang] and
[I-D.ietf-ccamp-otn-topo-yang], the type and encapsulation-type
attributes can be defined by technology- specific UNI
augmentations to represent the capability of a TP to be configured
as a L2VPN/L3VPN UNI Service Attachment Point (SAP).
The advantages of using a TE Topology profile would be having
common solutions for:
* discovering UNIs as well as inter-domain NNI links, which is
applicable to any technology (TE or non TE) used at the UNI or
within the network;
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* modelling non TE UNIs such as Ethernet, and TE UNIs such as OTN,
as well as UNIs which can configured as TE or non-TE (e.g., being
configured as either Ethernet or OTN UNI).
2.2. Administrative and Operational status management
The TE Topology Model supports the management of administrative and
operational state, including also the possibility to associate some
administrative names, for nodes, termination points and links. This
solution is generic and also does not require the network to be a TE
network.
The following profile of the TE Topology Model can be used for
administrative and operational state management:
module: ietf-te-topology
augment /nw:networks/nw:network/nw:network-types:
+--rw te-topology!
augment /nw:networks/nw:network:
+--rw te-topology-identifier
| +--rw provider-id? te-global-id
| +--rw client-id? te-global-id
| +--rw topology-id? te-topology-id
+--rw te!
+--rw name? string
augment /nw:networks/nw:network/nw:node:
+--rw te-node-id? te-types:te-node-id
+--rw te!
+--rw te-node-attributes
| +--rw admin-status? te-types:te-admin-status
| +--rw name? string
+--ro oper-status? te-types:te-oper-status
augment /nw:networks/nw:network/nt:link:
+--rw te!
+--rw te-link-attributes
| +--rw name? string
| +--rw admin-status? te-types:te-admin-status
+--ro oper-status? te-types:te-oper-status
augment /nw:networks/nw:network/nw:node/nt:termination-point:
+--rw te-tp-id? te-types:te-tp-id
+--rw te!
+--rw admin-status? te-types:te-admin-status
+--rw name? string
+--ro oper-status? te-types:te-oper-status
Figure 2: Generic Topology with admin and operational state
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The TE topology data model profile shown in Figure 2 is applicable to
any technology (TE or non-TE) that requires management of the
administrative and operational state and administrative names for
nodes, termination points and links.
2.3. Overlay and Underlay non-TE Topologies
The TE Topology model supports the management of overlay/underlay
relationship for nodes and links, as described in section 5.8 of
[RFC8795]. This solution is generic and does not require the network
to be a TE network.
The following TE topology data model profile can be used to manage
overlay/underlay network data:
module: ietf-te-topology
augment /nw:netorks/nw:network/nw:network-types:
+--rw te-topology!
augment /nw:networks/nw:network/nw:node:
+--rw te-node-id? te-types:te-node-id
+--rw te!
+--rw te-node-attributes
+--rw underlay-topology {te-topology-hierarchy}?
+--rw network-ref? -> /nw:networks/network/network-id
augment /nw:networks/nw:network/nt:link:
+--rw te!
+--rw te-link-attributes
+--rw underlay {te-topology-hierarchy}?
+--rw enabled? boolean
+--rw primary-path
+--rw network-ref?
| -> /nw:networks/network/network-id
+--rw path-element* [path-element-id]
+--rw path-element-id uint32
+--rw (type)?
+--:(numbered-link-hop)
| +--rw numbered-link-hop
| +--rw link-tp-id te-tp-id
| +--rw hop-type? te-hop-type
| +--rw direction? te-link-direction
+--:(unnumbered-link-hop)
+--rw unnumbered-link-hop
+--rw link-tp-id te-tp-id
+--rw node-id te-node-id
+--rw hop-type? te-hop-type
+--rw direction? te-link-direction
Figure 3: Generic Topology with overlay/underlay information
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This profile is applicable to any technology (TE or non-TE) when it
is needed to manage the overlay/underlay information. It is also
allows a TE underlay network to support a non-TE overlay network and,
vice versa, a non-TE underlay network to support a TE overlay
network.
2.4. Nodes with switching limitations
A node can have some switching limitations where connectivity is not
possible between all its TP pairs, for example when:
* the node represents a physical device with switching limitations;
* the node represents an abstraction of a network topology.
This scenario is generic and applies to both TE and non-TE
technologies.
A connectivity TE Topology profile data model supports the management
of the node connectivity matrix to represent feasible connections
between termination points across the nodes. This solution is
generic and does not necessarily require a TE enabled network.
The following profile of the TE Topology model can be used for nodes
with connectivity constraints:
module: ietf-te-topology
augment /nw:networks/nw:network/nw:network-types:
+--rw te-topology!
augment /nw:networks/nw:network/nw:node:
+--rw te-node-id? te-types:te-node-id
+--rw te!
+--rw te-node-attributes
+--rw connectivity-matrices
+--rw number-of-entries? uint16
+--rw is-allowed? boolean
+--rw connectivity-matrix* [id]
+--rw id uint32
+--rw from
| +--rw tp-ref? leafref
+--rw to
| +--rw tp-ref? leafref
+--rw is-allowed? boolean
Figure 4: Generic Topology with connectivity constraints
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The TE topology data model profile shown in Figure 4 is applicable to
any technology (TE or non-TE) networks that requires managing nodes
with certain connectivity constraints. When used with TE
technologies, additional TE attributes, as defined in [RFC8795], can
also be provided.
3. Technology-specific augmentations
There are two main options to define technology-specific Topology
Models which can use the attributes defined in the TE Topology Model
[RFC8795].
Both options are applicable to any possible profile of the TE
Topology Model, such as those defined in Section 2.
The first option is to define a technology-specific TE Topology Model
which augments the TE Topology Model, as shown in Figure 5:
+-------------------+
| Network Topology |
+-------------------+
^
|
| Augments
|
+-----------+-----------+
| TE Topology |
| (profile) |
+-----------------------+
^
|
| Augments
|
+----------+----------+
| Technology-Specific |
| TE Topology |
+---------------------+
Figure 5: Augmenting the TE Topology Model
This approach is more suitable for cases when the technology-specific
TE topology model provides augmentations to the TE Topology
constructs, such as bandwidth information (e.g., link bandwidth),
tunnel termination points (TTPs) or connectivity matrices. It also
allows providing augmentations to the Network Topology constructs,
such as nodes, links, and termination points (TPs).
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This is the approach currently used in
[I-D.ietf-ccamp-eth-client-te-topo-yang] and
[I-D.ietf-ccamp-otn-topo-yang].
It is worth noting that a profile of the technology-specific TE
Topology model not using any TE topology attribute or constructs can
be used to address any use case that do not require these attributes.
In this case, only the te-topology presence container of the TE
Topology Model needs to be implemented.
The second option is to define a technology-specific Network Topology
Model which augments the Network Topology Model and to rely on the
multiple inheritance capability, which is implicit in the network-
types definition of [RFC8345], to allow using also the generic
attributes defined in the TE Topology model:
+-----------------------+
| Network Topology |
+-----------------------+
^ ^
| |
Augments +---+ +--+ Augments
| |
+---------+---+ +----------+----------+
| TE Topology | | Technology-specific |
| (profile) | | Network Topology |
+-------------+ +---------------------+
Figure 6: Augmenting the Network Topology Model with multi-
inheritance
This approach is more suitable in cases where the technology-specific
Network Topology Model provides augmentation only to the constructs
defined in the Network Topology Model, such as nodes, links, and
termination points (TPs). Therefore, with this approach, only the
generic attributes defined in the TE Topology Model could be used.
It is also worth noting that in this case, technology-specific
augmentations for the bandwidth information could not be defined.
In principle, it would be also possible to define both a technology
specific TE Topology Model which augments the TE Topology Model, and
a technology-specific Network Topology Model which augments the
Network Topology Model and to rely on the multiple inheritance
capability, as shown in Figure 7:
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+-----------------------+
| Network Topology |
+-----------------------+
^ ^
| |
Augments +---+ +--+ Augments
| |
+---------+---+ +----------+----------+
| TE Topology | | Technology-specific |
| (profile) | | Network Topology |
+-------------+ +---------------------+
^ ^
| |
| Augments | References
| |
+----------+----------+ |
| Technology-Specific +--------------+
| TE Topology |
+---------------------+
Figure 7: Augmenting both the Network and TE Topology Models
This option does not provide any technical advantage with respect to
the first option, shown in Figure 5, but could be useful to add
augmentations to the TE Topology constructs and to re-use an already
existing technology-specific Network Topology Model.
It is worth noting that the technology-specific TE Topology model can
reference constructs defined by the technology-specific Network
Topology model but it could not augment constructs defined by the
technology-specific Network Topology model.
3.1. Multi-inheritance
As described in section 4.1 of [RFC8345], the network types should be
defined using presence containers to allow the representation of
network subtypes.
The hierachy of netwok subtypes can be single hierarchy, as shown in
Figure 5. In this case, each presence container contains at most one
child presence container, as shows in the JSON code below:
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{
"ietf-network:ietf-network": {
"ietf-te-topology:te-topology": {
"example-te-topology": {}
}
}
}
The hierachy of netwok subtypes can also be multi-hierarchy, as shown
in Figure 6 and Figure 7. In this case, one presence container can
contain more than one child presence containers, as show in the JSON
codes below:
{
"ietf-network:ietf-network": {
"ietf-te-topology:te-topology": {}
"example-network-topology": {}
}
}
{
"ietf-network:ietf-network": {
"ietf-te-topology:te-topology": {
"example-te-topology": {}
}
"example-network-topology": {}
}
}
Other examples of multi-hierarchy topologies are described in
[I-D.ietf-teas-yang-sr-te-topo].
3.2. Example (Link augmentation)
This section provides an example on how technology-specific
attributes can be added to the Link construct:
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+--rw link* [link-id]
+--rw link-id link-id
+--rw source
| +--rw source-node? -> ../../../nw:node/node-id
| +--rw source-tp? leafref
+--rw destination
| +--rw dest-node? -> ../../../nw:node/node-id
| +--rw dest-tp? leafref
+--rw supporting-link* [network-ref link-ref]
| +--rw network-ref
| | -> ../../../nw:supporting-network/network-ref
| +--rw link-ref leafref
+--rw example-link-attributes
| <...>
+--rw te!
+--rw te-link-attributes
+--rw name? string
+--rw example-te-link-attributes
| <...>
+--rw max-link-bandwidth
+--rw te-bandwidth
+--rw (technology)?
+--:(generic)
| +--rw generic? te-bandwidth
+--:(example)
+--rw example? example-bandwidth
Figure 8: Augmenting the Link with technology-specific attributes
The technology-specific attributes within the example-link-attributes
container can be defined either in the technology-specific TE
Topology Model (Option 1) or in the technology-specific Network
Topology Model (Option 2 or Option 3). These attributes can only be
non-TE and do not require the implementation of the te container.
The technology-specific attributes within the example-te-link-
attributes container as well as the example max-link-bandwidth can
only be defined in the technology-specific TE Topology Model (Option
1 or Option 3). These attributes can be TE or non-TE and require the
implementation of the te container.
4. Implemented profiles
When a server implements a profile of the TE topology model, it is
not clear how the server can report to the client the subset of the
model being implemented.
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It is also worth noting that the supported profile may also depend on
other attributes (for example the network type).
In case the TE topology profile is reported by the server to the
client, the server will report in the operational datastore only the
leaves which have been implemented, as described in section 5.3 of
[RFC8342].
More investigation is required in case the TE topology profile is
configured by the client.
5. Security Considerations
This document provides only information about how the TE Topology
Model, as defined in [RFC8795], can be profiled to address some
scenarios which are not considered as TE.
As such, this document does not introduce any additional security
considerations besides those already defined in [RFC8795].
6. IANA Considerations
This document requires no IANA actions.
Acknowledgments
The authors would like to thank Vishnu Pavan Beeram, Daniele
Ceccarelli, Jonas Ahlberg and Scott Mansfield for providing useful
suggestions for this draft.
This document was prepared using kramdown.
Initial versions of this document were prepared using 2-Word-
v2.0.template.dot.
References
Normative References
[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>.
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[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>.
Informative References
[I-D.ietf-ccamp-eth-client-te-topo-yang]
Yu, C., Zheng, H., Guo, A., Busi, I., Xu, Y., Zhao, Y.,
and X. Liu, "A YANG Data Model for Ethernet TE Topology",
Work in Progress, Internet-Draft, draft-ietf-ccamp-eth-
client-te-topo-yang-05, 9 October 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-ccamp-
eth-client-te-topo-yang-05>.
[I-D.ietf-ccamp-otn-topo-yang]
Zheng, H., Busi, I., Liu, X., Belotti, S., and O. G. de
Dios, "A YANG Data Model for Optical Transport Network
Topology", Work in Progress, Internet-Draft, draft-ietf-
ccamp-otn-topo-yang-17, 10 July 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-ccamp-
otn-topo-yang-17>.
[I-D.ietf-teas-rfc3272bis]
Farrel, A., "Overview and Principles of Internet Traffic
Engineering", Work in Progress, Internet-Draft, draft-
ietf-teas-rfc3272bis-27, 12 August 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-teas-
rfc3272bis-27>.
[I-D.ietf-teas-yang-sr-te-topo]
Liu, X., Bryskin, I., Beeram, V. P., Saad, T., Shah, H.
C., and S. Litkowski, "YANG Data Model for SR and SR TE
Topologies on MPLS Data Plane", Work in Progress,
Internet-Draft, draft-ietf-teas-yang-sr-te-topo-18, 21
October 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-teas-yang-sr-te-topo-18>.
[I-D.ogondio-opsawg-uni-topology]
de Dios, O. G., Barguil, S., Wu, Q., and M. Boucadair, "A
YANG Model for User-Network Interface (UNI) Topologies",
Work in Progress, Internet-Draft, draft-ogondio-opsawg-
uni-topology-01, 2 April 2020,
<https://datatracker.ietf.org/doc/html/draft-ogondio-
opsawg-uni-topology-01>.
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Contributors
Aihua Guo
Futurewei Inc.
Email: aihuaguo.ietf@gmail.com
Haomian Zheng
Huawei
Email: zhenghaomian@huawei.com
Sergio Belotti
Nokia
Email: sergio.belotti@nokia.com
Authors' Addresses
Italo Busi
Huawei
Email: italo.busi@huawei.com
Xufeng Liu
Alef Edge
Email: xufeng.liu.ietf@gmail.com
Igor Bryskin
Individual
Email: i_bryskin@yahoo.com
Tarek Saad
Cisco Systems Inc
Email: tsaad.net@gmail.com
Oscar Gonzalez de Dios
Telefonica
Email: oscar.gonzalezdedios@telefonica.com
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