Internet-Draft | Fine grain OTN YANG | October 2024 |
Tan, et al. | Expires 24 April 2025 | [Page] |
This document defines YANG data models to describe the topology and tunnel information of a fine grain Optical Transport Network. The YANG data models defined in this document are designed to meet the requirements for efficient transmission of sub-1G client signals in transport network.¶
This note is to be removed before publishing as an RFC.¶
The latest revision of this draft can be found at https://YuChaode.github.io/draft-tan-ccamp-fgotn-yang/draft-tan-ccamp-fgotn-yang.html. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-tan-ccamp-fgotn-yang/.¶
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Optical Transport Networks (OTN) is a mainstream layer 1 technology for the transport network. Over the years, it has continued to evolve, to improve its transport functions for the emerging requirements. The topology and tunnel information in the OTN has already been defined by generic traffic-engineering models and technology-specific models, including [I-D.ietf-ccamp-otn-topo-yang] and [I-D.ietf-ccamp-otn-tunnel-model].¶
In the latest version of OTN, ITU-T G.709/Y.1331 Edition 6.5 [ITU-T_G.709], the fine grain OTN (fgOTN) is introduced for the efficient transmission of low rate client signals (e.g., sub-1G).¶
This document presents the control interface requirements of fgOTN, and defines two YANG data models for fgOTN topology and fgOTN tunnel. The topology model can capture topological and resource-related information pertaining to fgOTN. This model also enables clients, which interact with a transport domain controller, for fgOTN topology related operations such as obtaining the relevant topology resource information. The fgOTN tunnel YANG data model defined in this document is used for the provisioning and management of fgOTN Traffic Engineering (TE) tunnels, Label Switched Paths (LSPs), and interfaces.¶
Furthermore, this document also imports the generic Layer 1 types defined in [I-D.ietf-ccamp-layer1-types].¶
The YANG data models defined in this document conform to the Network Management Datastore Architecture (NMDA) defined in [RFC8342].¶
Some of the key terms used in this document are listed as follow.¶
The following terms are defined in [RFC7950] and are not redefined here:¶
The following terms are defined in [RFC6241] and are not redefined here:¶
The terminology for describing YANG data models is found in [RFC7950].¶
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.¶
A simplified graphical representation of the data model is used in Section 6 of this document. The meaning of the symbols in this diagram is defined in [RFC8340].¶
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.¶
In this documents, names of data nodes and other data model objects are prefixed using the standard prefix associated with the corresponding YANG imported modules, as shown in the following table.¶
Prefix | Yang Module | Reference |
---|---|---|
l1-types | ietf-layer1-types | [RFC YYYY] |
otnt | ietf-otn-topology | [RFC ZZZZ] |
te | ietf-te | [RFC KKKK] |
otn-tnl | ietf-otn-tunnel | [RFC JJJJ] |
fgotnt | ietf-fgotn-topology | RFC XXXX |
fgotn-tnl | ietf-fgotn-tunnel | RFC XXXX |
RFC Editor Note: Please replace XXXX with the number assigned to the RFC once this draft becomes an RFC. Please replace YYYY with the RFC numbers assigned to [I-D.ietf-ccamp-layer1-types]. Please replace ZZZZ with the RFC numbers assigned to [I-D.ietf-ccamp-otn-topo-yang]. Please replace KKKK with the RFC numbers assigned to [I-D.ietf-teas-yang-te]. Please replace JJJJ with the RFC numbers assigned to [I-D.ietf-ccamp-otn-tunnel-model]. Please remove this note.¶
The tree diagrams extracted from the module(s) defined in this document are given in subsequent sections as per the syntax defined in [RFC8340].¶
FgOTN layer network is a service layer network of the OTN ODU layer network. In order to provide fgOTN capabilities, this document defines two extension YANG data models augmenting to TE topology and TE tunnel YANG model. The attributes related to fgOTN are augments from OTN topology data model, and fgOTN topology is not treated as a separate hierarchy. The fgOTN tunnel is defined as a separate tunnel hierarchy, and new fgOTN tunnels need to be pre-set and created during the service provisioning process.¶
The typical scenarios for fgOTN is to provide low bit rate private line or private network services for customers. Three scenarios that require special consideration are listed based on the characteristics of the fgOTN.¶
OTN network will cover a larger scope of networks, it may include the backbone network, metro core, metro aggregation, metro access, and even the OTN CPE in the customers' networks.¶
Figure 1 below shows an example of scenario to retrieve server tunnels. In this example, some small bandwidth fgOTN service are aggregated by the access ring (10G), and then aggregated into a bigger bandwidth in metro ring (100G). The allocation of TS maybe different in access ring and metro ring. E.g. there could be 3 timeslots allocated in the access ring while there could be 3 ODU2 are allocated in the metro ring.¶
As described in [ITU-T_G.709], the functional requirements of fgOTN include Support fgODUflex SNCP 1+1 protection. The protection of fgOTN service should rely on the protection of fgOTN tunnel. The server should provide all the hops of fgOTN tunnel, if the nodes cannot support fgOTN switching, the fg-ts in the LSP can be empty.¶
[ITU-T_G.709] defines the data plane procedure to support fgODUflex hitless resizing. The support of management of hitless resizing of fgODUflex needs to be further considered. Firstly, the range of fgOTN service's Bandwidth on Demand (BoD) cannot exceed its server layer's bandwidth. Secondly, the client needs to know how many bandwidth of a link is allocated for fgOTN. From a management point of view, we only need to plan a portion of resources to support fgOTN, without having to allocate all resources for fgOTN to use. As shown in Figure 3, only resource 1 is planned for fgOTN.¶
This document aims to describe the data model for fine grain OTN topology. The YANG module presented in this document augments from OTN topology data model, i.e., the ietf-otn-topology, as specified in [I-D.ietf-ccamp-otn-topo-yang]. In section 6 of [I-D.ietf-ccamp-otn-topo-yang], the guideline for augmenting OTN topology model was provided, and in this draft, we augment the OTN topology model to describe the topology characteristics of fgOTN.¶
Common types, identities and groupings defined in [I-D.ietf-ccamp-layer1-types] is reused in this document.¶
[RFC8345] defines an abstract (generic, or base) YANG data model for network/service topologies and inventories, and provides the fundamental model for [RFC8795]. OTN topology module in [I-D.ietf-ccamp-otn-topo-yang] augments from the TE topology YANG model defined in [RFC8795]. This work is not directly augmenting [RFC8345]. Figure 4 shows the augmentation relationship.¶
The entities, TE attributes and OTN attributes, such as node, termination points and links, are still applicable for describing an fgOTN topology and the model presented in this document only specifies technology-specific attributes/information. The fgOTN-specific attributes including the fgTS, can be used to represent the bandwidth and label information. At the same time, it is necessary to extend the encoding and switching-capability enumeration values in [I-D.busi-teas-te-types-update] to support fgOTN encapsulation and fgOTN switching.¶
There are a few characteristics augmenting to the OTN topology.¶
The fine grain tributary slot granularity (FGTSG) attribute defines the granularity, such as 10M, used by the TSs of a given OTN link.¶
A boolean value is specified to augment the generic TE link termination point to describe whether the point can support fgOTN switching capability.¶
augment /nw:networks/nw:network/nw:node/nt:termination-point/tet:te: +--rw supported-fgotn-tp? boolean¶
The boolean value supported-fgodu-tp is used to indicate whether the termination point can support fgOTN switching capability.¶
Based on the OTN topology model, we augment the bandwidth information of fgOTN, including the max-link-bandwidth and unreserved-bandwidth. The augmented parameter fgotn-bandwidth is used to indicate how much of the bandwidth has been allocated for the usage of fgOTN.¶
augment /nw:networks/nw:network/nt:link/tet:te/tet:te-link-attributes /tet:max-link-bandwidth/tet:te-bandwidth/otnt:otn-bandwidth /otnt:odulist: +--rw fgotn-bandwidth? string¶
The augmented fgotnlist structure is used to describe the unreserved TE bandwidth of fgOTN in the server ODUk. The odu-ts-number is used to indicate the index of server ODUk channel.¶
augment /nw:networks/nw:network/nt:link/tet:te/tet:te-link-attributes /tet:unreserved-bandwidth/tet:te-bandwidth /otnt:otn-bandwidth: +--rw fgotnlist* [odu-type odu-ts-number] +--rw odu-type identityref +--rw odu-ts-number? uint16 +--rw fgotn-bandwidth? string¶
The model augments the label-restriction list with fgOTN technology specific attributes using the otn-label-range-info grouping defined in [I-D.ietf-ccamp-layer1-types].¶
augment /nw:networks/tet:te/tet:templates/tet:link-template /tet:te-link-attributes/tet:label-restrictions /tet:label-restriction/otnt:otn-label-range: +--rw fgts-range* [odu-type odu-ts-number] +--rw odu-type identityref +--rw odu-ts-number? string +--rw fgts-reserved? string +--rw fgts-unreserved? string¶
The fgts-range list is used to describe the availability of fgOTN timeslot in the server ODUk, including the fgts-reserved and fgts-unreserved. The odu-ts-number is used to indicate the index of server ODUk channel.¶
This document aims to describe the data model for fgOTN tunnel. The fgOTN tunnel model augments to OTN tunnel [I-D.ietf-ccamp-otn-tunnel-model] with fgOTN-specific parameters, including the bandwidth information and label information. Figure 5 shows the augmentation relationship.¶
It's also worth noting that the fgOTN tunnel provisioning is usually based on the fgOTN topology. Therefore the fgOTN tunnel model is usually used together with fgOTN topology model specified in this document. The OTN tunnel model also imports a few type modules, including ietf-te-types and ietf-otn-types. A new enumeration value prot-fgoduflex in ietf-otn-types should be defined to indicate the fgotn tunnel.¶
The model augment TE bandwidth information of fgOTN tunnel.¶
augment /te:te/te:tunnels/te:tunnel/te:te-bandwidth/te:technology /otn-tnl:otn: +--rw fgoduflex-bandwidth? string¶
The string value fgoduflex-bandwidth is used to indicate the bandwidth of this fgOTN tunnel.¶
The module augments TE label-hop for the explicit route objects included or excluded by the path computation of the primary paths and secondary-paths using the fgts-numbers. The fgts-numbers is used to specify fgTS information on inter-domain ports of the routing path. We also augment the TE label-hop for the record route of the LSP using the fgts-numbers.¶
Figure 6 below shows the tree diagram of the YANG data model defined in module "ietf-fgotn-topology" (Figure 7).¶
Figure 8 below shows the tree diagram of the YANG data model defined in module "ietf-fgotn-tunnel" (Figure 9).¶
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