Internet DRAFT - draft-yby-netmod-usecase-of-ymc
draft-yby-netmod-usecase-of-ymc
Internet Engineering Task Force B. Yan, Ed.
Internet-Draft Z. Li, Ed.
Intended status: Informational Y. Zhao, Ed.
Expires: November 15, 2020 Beijing Univ. of Posts and Telecom.
May 14, 2020
The use cases of yang model conversion
draft-yby-netmod-usecase-of-ymc-00
Abstract
This document contains the brief description and the guidelines for
the usage of Yang model conversion (YMC). It demonstrates the
benefits of YMC for both communication vendors and network operators,
provides several use cases to show the proper operations, and
provides the recommendations for the development.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Keywords . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. The usage limitation of Yang model conversion . . . . . . . . 3
4. Use cases for Yang model conversion . . . . . . . . . . . . . 4
4.1. Use case for vendors . . . . . . . . . . . . . . . . . . 4
4.2. Use case for operators . . . . . . . . . . . . . . . . . 4
4.3. Use case for multiple Yang model organizations . . . . . 5
5. Considerations by using YMC . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. Security Considerations . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 7
Appendix A. Additional Stuff . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
The Yang standards with version 1.0 RFC 6020 [RFC6020] and version
1.1 RFC 7950 [RFC7950] define a domain- specific language for network
data modeling. By using Yang models, several network management
protocols like NETCONF [RFC6241] and RESTCONF [RFC8040] are proposed.
These protocols are deployed widely in network management systems
(including network controllers in SDN). The Yang-model-driven
systems generally generate codes from yang models by using Yang
compiler, and executes network operations on these model data. A lot
of Yang models are defined for the networks in different layers. The
combination of multiple Yang models form a complete network model
under specific scenarios.
A Yang model is composed of different statements. According to the
descriptions in Yang standards, these statements could be divided
into module statement, submodule statement, typedef statement,
container statement, leaf-list statement, list statement, choice
statement, etc. In order to manage the updates for Yang models in
the equipment development, Yang standard introduces revision
statement and augment statement to indicate the version and extension
for a Yang model. However, these statements could only handle the
model management in an incremental updating way, but couldn't handle
the mapping problem between two similar Yang models. And with the
widespread adoption of Yang, such a mapping problem occurs.
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Until now, many Yang models have been defined by different
organizations, vendors, network operators, and foundations. These
existed Yang models are deployed in different scenarios. However,
these models don't coordinate with each other very well. For a
certain part, the authors usually define duplicated and conflicted
models to make this part meet their own requirements. And once the
data conversion from one model to another is required, there is no
such a solution defined. In order to address this problem, Yang
model conversion is introduced. In reality, such a model conversion
happens when:
o A vendor is required to provide different models for different
customers (telecom operators, cloud computing companies, etc.) on
the same equipment.
o A network operator needs to map all network models defined by all
network equipment into its own complete network model.
o An organization needs to map its own models into the models
defined by another organization.
The conversion between two Yang models enables the concrete
definition of model difference. In all conversion use cases, such a
definition enhances the conversion robustness. Besides, it also make
all gap between models evaluable.
2. Keywords
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
3. The usage limitation of Yang model conversion
The model conversion MAY introduce information loss or information
deviation while mapping the data from one model to another.
Therefore, the conversion could not be applied when the gap between
two models are non-negligible. Usually, only the mapping between two
models that define the same equipment component MAY succeeds. Yang
model conversion is not recommended if the mapping problem could be
solved by simple augmentation, or other solutions without information
loss or information deviation.
In database, there MAY be only one model stored, and other model data
are generated by Yang model conversion timely. Some nodes defined in
schema tree MAY be skipped after model conversion. If the rpc
service or notification service include these skipped nodes, these
services are not available.
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4. Use cases for Yang model conversion
Yang model conversion is useful for all users. The following use
cases show how to use it:
4.1. Use case for vendors
Matching between vendor's private model and operator's models.
+-------------------------------------+
| Communication Equipment |
| |
| +---------------------+ |
| | internal YANG model | |
| +---------------------+ |
| /\ |
| Sync || |
| \/ |
| +---------------------+ |
| |Yang Model Conversion| |
| +---------------------+ |
| | | | |
| +---------+ +---------+ +---------+ |
| | model A | | model B | | model X | |
| +---------+ +---------+ +---------+ |
| / | \ |
+-------------------------------------+
/ | \
/ | \
/ | ... \
+------------+ +------------+ +------------+
| Operator A | | Operator B | ... | Operator X |
+------------+ +------------+ +------------+
mapping from vendor internal model to multiple operators' models.
Figure 1
4.2. Use case for operators
Matching between operator's private model to vendor's models.
Data migration for the existed huge performance data.
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+-------------------------------+
| Network Controller |
| |
| +---------------------+ |
| | internal YANG model | |
| +---------------------+ |
| /\ |
| Sync || |
| \/ |
| +---------------------+ |
| |Yang Model Conversion| |
| +---------------------+ |
| / | \ |
+-------------------------------+
/ | \
/ | \
/ | ... \
+-------------+ +-------------+ +-------------+
| Equipment A | | Equipment B | ... | Equipment X |
+-------------+ +-------------+ +-------------+
mapping from multiple equipment model to one model.
Figure 2
4.3. Use case for multiple Yang model organizations
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+---------------------------------+
| organization A |
____|__\ +-----------------------+ |
| | / | model A1 | /__|__
| | +-----------------------+ \ | |
| | +-----------------------+ | |
| | | model A2 | /__|__|_____________
| | +-----------------------+ \ | | |
| | /\ | | |
| +-----|---------------------------+ | |
| _____|_________________________ | |
| | | | | |
| | | __________________________________ |
| | | | | | | |
+-----------------------------+ +-----------------------------+
| | | | | | | | | | | |
| \/ \/ \/ \/ | | \/ \/ \/ \/ |
| +----------+ +----------+ | | +----------+ +----------+ |
| | model B1 | | model B2 | | | | model C1 | | model C2 | |
| +----------+ +----------+ | | +----------+ +----------+ |
| organization B | | organization C |
+-----------------------------+ +-----------------------------+
mapping from multiple equipment model to one model.
Figure 3
5. Considerations by using YMC
6. Acknowledgements
This document is Supported by BUPT Excellent Ph.D. Students
Foundation (CX2019314).
7. IANA Considerations
This memo includes no request to IANA.
8. Security Considerations
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>.
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[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>.
[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>.
9.2. Informative References
[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>.
[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>.
Appendix A. Additional Stuff
This becomes an Appendix.
Authors' Addresses
Boyuan Yan (editor)
Beijing Univ. of Posts and Telecom.
No. 10 Xitucheng Rd.
Beijing, Haidian Dist.
CN
Phone: +86 188 1052 8290
Email: yanboyuan@bupt.edu.cn
Zhuotong Li (editor)
Beijing Univ. of Posts and Telecom.
No. 10 Xitucheng Rd.
Beijing, Haidian Dist.
CN
Email: lizhuotong@bupt.edu.cn
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Yongli Zhao (editor)
Beijing Univ. of Posts and Telecom.
No. 10 Xitucheng Rd.
Beijing, Haidian Dist.
CN
Email: yonglizhao@bupt.edu.cn
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