]> A YANG Data Model for Virtual Network (VN) Operations Samsung Electronics
younglee.tx@gmail.com
Huawei
India dhruv.ietf@gmail.com
Cisco
daniele.ietf@gmail.com
Individual
i_bryskin@yahoo.com
ETRI
byyun@etri.re.kr
TEAS Working Group A Virtual Network (VN) is a network provided by a service provider to a customer for the customer to use in any way it wants. This document provides a YANG data model generally applicable to any mode of VN operations. This includes VN operations as per Abstraction and Control of TE Networks (ACTN) framework.
Introduction Abstraction and Control of Traffic Engineered Networks (ACTN) describes a set of management and control functions used to operate one or more TE networks to construct Virtual Network (VN) that can be represented to customers and that are built from abstractions of the underlying TE networks . This document provides a YANG data model generally applicable to any mode of VN operation. ACTN is the primary example of the usage of the VN YANG model but not limited to it. The VN model defined in this document is applicable in a generic sense as an independent model in and of itself. The VN model defined in this document can also work together with other customer service models such as the Layer Three Virtual Private Network Service Model (L3SM) , the Layer Two Virtual Private Network Service Model (L2SM) and the Layer One Connectivity Service Model (L1CSM) to provide a complete life-cycle service management and operations. The YANG model discussed in this document basically provides the following:
  • Characteristics of Access Points (APs) that describe customer's endpoint characteristics;
  • Characteristics of Virtual Network Access Points (VNAP) that describe how an AP is partitioned for multiple VNs sharing the AP and its reference to a Link Termination Point (LTP) of the Provider Edge (PE) Node;
  • Characteristics of Virtual Networks (VNs) that describe the customer's VN in terms of multiple VN Members comprising a VN, multi-source and/or multi-destination characteristics of the VN Member, the VN's reference to TE-topology's Abstract Node;
An abstract TE topology is a topology that contains abstract topological elements (nodes, links) created and customised based on customer's preference . The actual VN instantiation and computation is performed with Connectivity Matrices of the TE-Topology Model which provides a TE network topology abstraction and management operation. As per , a TE node connectivity matrix is the TE node's switching limitations in the form of valid switching combinations of the TE node's LTPs and potential TE paths. The VN representation relies on a single abstract TE node with a connectivity matrix. The VN can be abstracted as a set of edge-to-edge links (a Type 1 VN). Each link is the VN member that is mapped to the connectivity matrix entry (). The VN can also be abstracted as a topology of virtual nodes and virtual links (a Type 2 VN). Alongside the mapping of VN members to connectivity matrix entry, an underlay path can also be specified (). Once the TE-topology Model is used in triggering VN instantiation over the networks, the TE-tunnel Model will inevitably interact with the TE-Topology model for setting up actual tunnels and LSPs under the tunnels. Sections 2 and 3 provide a discussion of how the VN YANG model is applicable to the ACTN context where Virtual Network Service (VNS) operation is implemented for the Customer Network Controller (CNC)- Multi-Domain Service Coordinator (MDSC) interface (CMI). The YANG model on the CMI is also known as the customer service model in . The YANG model discussed in this document is used to operate customer-driven VNs during the VN instantiation, VN computation, and its life-cycle service management and operations. The VN operational state is included in the same tree as the configuration consistent with Network Management Datastore Architecture (NMDA) . The origin of the data is indicated as per the origin metadata annotation.
Terminology Refer to , , and for the key terms used in this document.
Tree Diagram A simplified graphical representation of the data model is used in Section 5 of this document. The meaning of the symbols in these diagrams is defined in .
Prefixes in Data Node Names In this document, 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 Table 1. Prefixes and corresponding YANG modules
Prefix YANG module Reference
vn ietf-vn [RFCXXXX]
yang ietf-yang-types
nw ietf-network
nt ietf-network-topology
te-types ietf-te-types
tet ietf-te-topology
Note: The RFC Editor will replace XXXX with the number assigned to the RFC once this draft becomes an RFC.
Use-case of VN YANG Model in the ACTN context In this section, ACTN is being used to illustrate the general usage of the VN YANG model. The model presented in this section has the following ACTN context.
ACTN CMI
Both ACTN VN YANG and TE-topology models are used over the CMI to establish a VN over TE networks as shown in .
Type 1 VN As defined in , a Virtual Network is a customer view of the TE network. To recapitulate VN types from , Type 1 VN is defined as follows:
The VN can be seen as a set of edge-to-edge abstract links (a Type 1 VN). Each abstract link is referred to as a VN member and is formed as an end-to-end tunnel across the underlying networks. Such tunnels may be constructed by recursive slicing or abstraction of paths in the underlying networks and can encompass edge points of the customer's network, access links, intra-domain paths, and inter- domain links.
If we were to create a VN where we have four VN-members as follows:
Where L1, L2, L3, L4, L7 and L8 correspond to a Customer End-Point, respectively.
This VN can be modeled as one abstract node representation as follows in Figure 2:
Abstract Node (One node topology)
Modeling a VN as one abstract node is the easiest way for customers to express their end-to-end connectivity as shown in .
Type 2 VN For some VN members, the customers are allowed to configure the intended path. To achieve this, alongside the single node abstract topology, an underlay topology is also needed. The underlay topology could be native TE topology or an abstract TE topology. The intended path is set based on the nodes and links of the underlay topology. Type 1 VN can be seen as a higher abstraction of a Type 2 VN (in which along with a single node abstract topology, an underlay topology and the intended path is specified). These topologies could be mutually agreed between CNC and MDSC prior to VN creation or it could be created as part of VN instantiation. If a Type 2 VN is desired for some or all of VN members of a type 1 VN (see the example in ), the TE-topology model can provide the following abstract topologies (a single node topology AN1 and a underlay topology (with nodes S1 to S11 and corresponding links)).
Type 2 topology
As shown in , the abstract node is AN1 and an underlay topology is depicted with nodes and links (S1 to S11). As an example, if VN-member 1 (L1-L4) is chosen to configure its own path over Type 2 topology, it can select, say, a path that consists of the explicit abstract path {S3,S4,S5} based on the underlay topology and its service requirement. This capability is enacted via TE-topology configuration by the customer.
High-Level Control Flows with Examples
Type 1 VN Illustration If this VN is Type 1, the following diagram shows the message flow between CNC and MDSC to instantiate this VN using VN and TE-Topology Models.
Type 1 VN Illustration | | HTTP 200 | |<--------------------------------| | | CNC POST the | POST /virtual-network | VN identifying |-------------------------------->| If there is AP, VNAP and VN- | | multi-src/dest Members and maps | | then MDSC to the TE-topo | HTTP 200 | selects a |<--------------------------------| src or dest | | and updates | | VN YANG CNC GET the | GET /virtual-network | VN YANG status |-------------------------------->| | | | HTTP 200 (VN with status: | | selected VN-members | | in case of multi s-d) | |<--------------------------------| | | ]]>
Type 2 VN Illustration For some VN members, the customer may want to "configure" explicit path that connects its two end-points. Let us consider the following example.
  • VN-Member 1
    L1-L4 (via S3, S4, and S5)
    VN-Member 2
    L1-L7 (via S3, S4, S7 and S8)
    VN-Member 3
    L2-L7 (via S9, S10, and S11)
    VN-Member 4
    L3-L8 (via S9, S10 and S11)
There are two options depending on whether CNC or MDSC creates the single abstract node topology. Case 1: If CNC creates the single abstract node topology, the following diagram shows the message flow between CNC and MDSC to instantiate this VN using VN and TE-Topology Model.
Type 2 VN Illustration, Case 1 | Explicit paths in| | the conn. matrix)| HTTP 200 | |<----------------------------------------| | | CNC POST the | POST /virtual-network | VN identifying |---------------------------------------->| AP, VNAP and VN- | | Members and maps | | to the TE-topo | HTTP 200 | |<----------------------------------------| | | | | CNC GET the | GET /virtual-network | VN YANG status |---------------------------------------->| | | | HTTP 200 (VN with status) | |<----------------------------------------| | | ]]>
Case 2: On the other hand, if MDSC create the single abstract node topology based VN YANG posted by the CNC, the following diagram shows the message flow between CNC and MDSC to instantiate this VN using VN and TE-Topology Models.
Type 2 VN Illustration, Case 2 | a single Abst. | HTTP 200 | node topology |<--------------------------------| by itself | | CNC GET VN & | GET /virtual-network & | POST TE-Topo | POST /nw:networks/nw:network/ | Models (with | nw:node/te-node-id/tet: | Conn. Matrix | connectivity-matrices/ | on the | tet:connectivity-matrix | Abstract Node |-------------------------------->| and explicit | | paths in the | | conn. matrix) | | | HTTP 200 | |<--------------------------------| | | | | CNC GET the | GET /virtual-network | VN YANG status |-------------------------------->| | | | HTTP 200 (VN with status) | |<--------------------------------| | | ]]>
Note that the underlay topology (which is referred by the single abstract node topology) could be a Native/White topology or a Grey topology () that is further customised based on the requirements of the customer and configured at MDSC. provides JSON examples for both VN model and TE-topology Connectivity Matrix sub-model to illustrate how a VN can be created by the CNC making use of the VN module as well as the TE-topology Connectivity Matrix module.
VN and AP Usage The customer access information may be known at the time of VN creation. A shared logical AP identifier is used between the customer and the operator to identify the access link between Customer Edge (CE) and Provider Edge (PE) . This is described in Section 6 of . In some VN operations, the customer access may not be known at the initial VN creation. The VN operation allow a creation of VN with only PE identifier as well. The customer access information could be added later. To achieve this the 'ap' container has a leaf for 'pe' node that allows AP to be created with PE information. The vn-member (and vn) could use APs that only have PE information initially.
VN Model Usage
Customer view of VN The VN-YANG model allows to define a customer view, and allows the customer to communicate using the VN constructs as described in the . It also allows to group the set of edge-to-edge links (i.e., VN members) under a common umbrella of VN. This allows the customer to instantiate and view the VN as one entity, making it easier for some customers to work on VN without worrying about the details of the provider based YANG models. This is similar to the benefits of having a separate YANG model for the customer services as described in , which states that service models do not make any assumption of how a service is actually engineered and delivered for a customer.
Auto-creation of VN by MDSC The VN could be configured at the MDSC explicitly by the CNC using the VN YANG model. In some other cases, the VN is not explicitly configured, but created automatically by the MDSC based on the customer service model and local policy, even in these case the VN YANG model can be used by the CNC to learn details of the underlying VN created to meet the requirements of customer service model.
Innovative Services
VN Compute VN Model supports VN compute (pre-instantiation mode) to view the full VN as a single entity before instantiation. Achieving this via path computation or "compute only" tunnel setup does not provide the same functionality.
VN Compute | constraints in | | the conn. matrix)| HTTP 200 | |<----------------------------------------| | | | | CNC calls RPC to | RPC /vn-compute | compute the VN |---------------------------------------->| as per the | | refered TE-Topo | | | | | HTTP 200 (Computed VN) | |<----------------------------------------| | | ]]>
The VN compute RPC allow you to optionally include the constraints and the optimization criteria at the VN as well as at the individual VN-member level. Thus, the RPC can be used independently to get the computed VN result without creating an abstract topology first.
VN Compute | as per the | | constraints and | | VN-Members | | | HTTP 200 (Computed VN) | |<----------------------------------------| | | ]]>
In either case the output includes a reference to the single node abstract topology with each VN-member including a reference to the connectivity-matrix-id where the path properties could be found. To achieve this the VN-compute RPC reuses the following common groupings:
  • te-types:generic-path-constraints: This is used optionally in the RPC input at the VN and/or VN-member level. The VN-member level overrides the VN-level data. This also overrides any constraints in the referenced abstract node in the TE topology.
  • te-types:generic-path-optimization: This is used optionally in the RPC input at the VN and/or VN-member level. The VN-member level overrides the VN-level data. This also overrides any optimization in the referenced abstract node in the TE topology.
  • vn-member: This identifies the VN member in both RPC input and output.
  • vn-policy: This is used optionally in the RPC input to apply any VN level policies.
When MDSC receives this RPC it computes the VN based on the input provided in the RPC call. This computation does not create a VN or reserve any resources in the system, it simply computes the resulting VN based on information at the MDSC or in coordination with the CNC. A single node abstract topology is used to convey the result of the each VN member as a reference to the connectivity-matrix-id. In case of error, the error information is included. /nw:networks/network/node/tet:te-node-id | +---w path-constraints | | +---w te-bandwidth | | | +---w (technology)? | | | ... | | +---w link-protection? identityref | | +---w setup-priority? uint8 | | +---w hold-priority? uint8 | | +---w signaling-type? identityref | | +---w path-metric-bounds | | | +---w path-metric-bound* [metric-type] | | | ... | | +---w path-affinities-values | | | +---w path-affinities-value* [usage] | | | ... | | +---w path-affinity-names | | | +---w path-affinity-name* [usage] | | | ... | | +---w path-srlgs-lists | | | +---w path-srlgs-list* [usage] | | | ... | | +---w path-srlgs-names | | | +---w path-srlgs-name* [usage] | | | ... | | +---w disjointness? te-path-disjointness | +---w cos? te-types:te-ds-class | +---w optimizations | | +---w (algorithm)? | | +--:(metric) {path-optimization-metric}? | | | ... | | +--:(objective-function) | | {path-optimization-objective-function}? | | ... | +---w vn-member-list* [vnm-id] | | +---w vnm-id vnm-id | | +---w src | | | +---w src? -> /access-point/ap/ap-id | | | +---w src-vn-ap-id? | | | | -> /access-point/ap/vn-ap/vn-ap-id | | | +---w multi-src? boolean {multi-src-dest}? | | +---w dest | | | +---w dest? -> /access-point/ap/ap-id | | | +---w dest-vn-ap-id? | | | | -> /access-point/ap/vn-ap/vn-ap-id | | | +---w multi-dest? boolean {multi-src-dest}? | | +---w connectivity-matrix-id? leafref | | +---w underlay | | +---w path-constraints | | | +---w te-bandwidth | | | | ... | | | +---w link-protection? identityref | | | +---w setup-priority? uint8 | | | +---w hold-priority? uint8 | | | +---w signaling-type? identityref | | | +---w path-metric-bounds | | | | ... | | | +---w path-affinities-values | | | | ... | | | +---w path-affinity-names | | | | ... | | | +---w path-srlgs-lists | | | | ... | | | +---w path-srlgs-names | | | | ... | | | +---w disjointness? te-path-disjointness | | +---w cos? te-types:te-ds-class | | +---w optimizations | | +---w (algorithm)? | | ... | +---w vn-level-diversity? | te-types:te-path-disjointness +--ro output +--ro te-topology-identifier | +--ro provider-id? te-global-id | +--ro client-id? te-global-id | +--ro topology-id? te-topology-id +--ro abstract-node? | -> /nw:networks/network/node/tet:te-node-id +--ro vn-member-list* [vnm-id] +--ro vnm-id vnm-id +--ro src | +--ro src? -> /access-point/ap/ap-id | +--ro src-vn-ap-id? | | -> /access-point/ap/vn-ap/vn-ap-id | +--ro multi-src? boolean {multi-src-dest}? +--ro dest | +--ro dest? -> /access-point/ap/ap-id | +--ro dest-vn-ap-id? | | -> /access-point/ap/vn-ap/vn-ap-id | +--ro multi-dest? boolean {multi-src-dest}? +--ro connectivity-matrix-id? leafref +--ro underlay +--ro if-selected? boolean | {multi-src-dest}? +--ro compute-status? vn-compute-status +--ro error-info +--ro error-description? string +--ro error-timestamp? yang:date-and-time +--ro error-reason? identityref ]]>
Multi-sources and Multi-destinations In creating a virtual network, the list of sources or destinations or both may not be pre-determined by the customer. For instance, for a given source, there may be a list of multiple-destinations to which the optimal destination may be chosen depending on the network resource situations. Likewise, for a given destination, there may also be multiple-sources from which the optimal source may be chosen. In some cases, there may be a pool of multiple sources and destinations from which the optimal source-destination may be chosen. The following YANG module is shown for describing source container and destination container. The following YANG tree shows how to model multi-sources and multi-destinations. /nw:networks/network/node/tet:te-node-id +--rw vn-member* [vnm-id] | +--rw vnm-id vnm-id | +--rw src | | +--rw src? -> /access-point/ap/ap-id | | +--rw src-vn-ap-id? | | | -> /access-point/ap/vn-ap/vn-ap-id | | +--rw multi-src? boolean {multi-src-dest}? | +--rw dest | | +--rw dest? -> /access-point/ap/ap-id | | +--rw dest-vn-ap-id? | | | -> /access-point/ap/vn-ap/vn-ap-id | | +--rw multi-dest? boolean {multi-src-dest}? | +--rw connectivity-matrix-id? leafref | +--rw underlay | +--ro oper-status? te-types:te-oper-status | +--ro if-selected? boolean {multi-src-dest}? +--rw admin-status? te-types:te-admin-status +--ro oper-status? te-types:te-oper-status +--rw vn-level-diversity? te-types:te-path-disjointness ]]>
Others The VN YANG model can be easily augmented to support the mapping of VN to the Services such as L3SM and L2SM as described in . The VN YANG model can be extended to support telemetry, performance monitoring and network autonomics as described in . Note that the YANG model is tightly coupled with the TE Topology model . Any underlay technology not supported by is also not supported by this model. The model does include an empty container called "underlay" that can be augmented. For example the SR-policy information can be augmented for the SR underlay by a future model. Apart from the te-types:generic-path-constraints and te-types:generic-path-optimization, an additional leaf cos for class of service is added to represent the Class-Type of traffic to be used as one of the path constraints.
Summary This section summarizes the innovative service features of the VN YANG.
  • Maintenance of AP and VNAP along with VN
  • VN construct to group of edge-to-edge links
  • VN Compute (pre-instantiate)
  • Multi-Source / Multi-Destination
  • Ability to support various VN and VNS Types
    • VN Type 1: Customer configures the VN as a set of VN Members. No other details need to be set by customer, making for a simplified operations for the customer.
    • VN Type 2: Along with VN Members, the customer could also provide an abstract topology, this topology is provided by the Abstract TE Topology YANG Model.
    • Note that the VN Type is not explicitly identified in the VN Yang model, as the VN Model is exactly the same for both VN Type 1 and 2. The VN type can be implicitly known based on the referenced TE topology and whether the connectivity matrix includes the underlay path (Type 2) or not (Type 1).
VN YANG Model (Tree Structure) /nw:networks/network/node/tet:te-node-id | +--rw max-bandwidth? te-types:te-bandwidth | +--rw avl-bandwidth? te-types:te-bandwidth | +--rw vn-ap* [vn-ap-id] | +--rw vn-ap-id ap-id | +--rw vn? -> /virtual-network/vn/vn-id | +--rw abstract-node? | | -> /nw:networks/network/node/tet:te-node-id | +--rw ltp? leafref | +--ro max-bandwidth? te-types:te-bandwidth +--rw virtual-network +--rw vn* [vn-id] +--rw vn-id vn-id +--rw te-topology-identifier | +--rw provider-id? te-global-id | +--rw client-id? te-global-id | +--rw topology-id? te-topology-id +--rw abstract-node? | -> /nw:networks/network/node/tet:te-node-id +--rw vn-member* [vnm-id] | +--rw vnm-id vnm-id | +--rw src | | +--rw src? -> /access-point/ap/ap-id | | +--rw src-vn-ap-id? -> /access-point/ap/vn-ap/vn-ap-id | | +--rw multi-src? boolean {multi-src-dest}? | +--rw dest | | +--rw dest? -> /access-point/ap/ap-id | | +--rw dest-vn-ap-id? -> /access-point/ap/vn-ap/vn-ap-id | | +--rw multi-dest? boolean {multi-src-dest}? | +--rw connectivity-matrix-id? leafref | +--rw underlay | +--ro oper-status? te-types:te-oper-status | +--ro if-selected? boolean {multi-src-dest}? +--rw admin-status? te-types:te-admin-status +--ro oper-status? te-types:te-oper-status +--rw vn-level-diversity? te-types:te-path-disjointness rpcs: +---x vn-compute +---w input | +---w te-topology-identifier | | +---w provider-id? te-global-id | | +---w client-id? te-global-id | | +---w topology-id? te-topology-id | +---w abstract-node? | | -> /nw:networks/network/node/tet:te-node-id | +---w path-constraints | | +---w te-bandwidth | | | +---w (technology)? | | | ... | | +---w link-protection? identityref | | +---w setup-priority? uint8 | | +---w hold-priority? uint8 | | +---w signaling-type? identityref | | +---w path-metric-bounds | | | +---w path-metric-bound* [metric-type] | | | ... | | +---w path-affinities-values | | | +---w path-affinities-value* [usage] | | | ... | | +---w path-affinity-names | | | +---w path-affinity-name* [usage] | | | ... | | +---w path-srlgs-lists | | | +---w path-srlgs-list* [usage] | | | ... | | +---w path-srlgs-names | | | +---w path-srlgs-name* [usage] | | | ... | | +---w disjointness? te-path-disjointness | +---w cos? te-types:te-ds-class | +---w optimizations | | +---w (algorithm)? | | +--:(metric) {path-optimization-metric}? | | | ... | | +--:(objective-function) | | {path-optimization-objective-function}? | | ... | +---w vn-member-list* [vnm-id] | | +---w vnm-id vnm-id | | +---w src | | | +---w src? -> /access-point/ap/ap-id | | | +---w src-vn-ap-id? -> /access-point/ap/vn-ap/vn-ap-id | | | +---w multi-src? boolean {multi-src-dest}? | | +---w dest | | | +---w dest? -> /access-point/ap/ap-id | | | +---w dest-vn-ap-id? | | | | -> /access-point/ap/vn-ap/vn-ap-id | | | +---w multi-dest? boolean {multi-src-dest}? | | +---w connectivity-matrix-id? leafref | | +---w underlay | | +---w path-constraints | | | +---w te-bandwidth | | | | ... | | | +---w link-protection? identityref | | | +---w setup-priority? uint8 | | | +---w hold-priority? uint8 | | | +---w signaling-type? identityref | | | +---w path-metric-bounds | | | | ... | | | +---w path-affinities-values | | | | ... | | | +---w path-affinity-names | | | | ... | | | +---w path-srlgs-lists | | | | ... | | | +---w path-srlgs-names | | | | ... | | | +---w disjointness? te-path-disjointness | | +---w cos? te-types:te-ds-class | | +---w optimizations | | +---w (algorithm)? | | ... | +---w vn-level-diversity? te-types:te-path-disjointness +--ro output +--ro te-topology-identifier | +--ro provider-id? te-global-id | +--ro client-id? te-global-id | +--ro topology-id? te-topology-id +--ro abstract-node? | -> /nw:networks/network/node/tet:te-node-id +--ro vn-member-list* [vnm-id] +--ro vnm-id vnm-id +--ro src | +--ro src? -> /access-point/ap/ap-id | +--ro src-vn-ap-id? -> /access-point/ap/vn-ap/vn-ap-id | +--ro multi-src? boolean {multi-src-dest}? +--ro dest | +--ro dest? -> /access-point/ap/ap-id | +--ro dest-vn-ap-id? | | -> /access-point/ap/vn-ap/vn-ap-id | +--ro multi-dest? boolean {multi-src-dest}? +--ro connectivity-matrix-id? leafref +--ro underlay +--ro if-selected? boolean {multi-src-dest}? +--ro compute-status? vn-compute-status +--ro error-info +--ro error-description? string +--ro error-timestamp? yang:date-and-time +--ro error-reason? identityref ]]>
VN YANG Model The YANG model is as follows: WG List: Editor: Young Lee : Dhruv Dhody "; description "This module contains a YANG module for the Virtual Network (VN). It describes a VN operation module that can take place in the context of the Customer Network Controller (CNC)- Multi-Domain Service Coordinator (MDSC) interface (CMI) of the Abstraction and Control of Traffic Engineered Networks (ACTN) architecture where the CNC is the actor of a VN Instantiation/modification/deletion as per RFC 8453. Copyright (c) 2024 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 Revised 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; see the RFC itself for full legal notices."; revision 2024-05-16 { description "initial version."; reference "RFC XXXX: A YANG Data Model for Virtual Network (VN) Operations"; } /* Features */ feature multi-src-dest { description "Support for selection of one src or destination among multiple."; reference "RFC 8453: Framework for Abstraction and Control of TE Networks (ACTN)"; } /* Typedef */ typedef vn-id { type string { length "1..max"; } description "A type definition for Virtual Network (VN) identifier."; } typedef ap-id { type string { length "1..max"; } description "A type definition for Access Point (AP) identifier."; } typedef vnm-id { type string { length "1..max"; } description "A type definition for VN member identifier."; } typedef vn-compute-status { type te-types:te-common-status; description "A type definition for representing the VN compute status. Note that all status apart from up and down are considered as unknown."; } /* identities */ identity vn-computation-error-reason { description "Base identity for VN computation error reasons."; } identity vn-computation-error-not-ready { base vn-computation-error-reason; description "VN computation has failed because the MDSC is not ready"; } identity vn-computation-error-no-cnc { base vn-computation-error-reason; description "VN computation has failed because one or more dependent CNC are unavailable."; } identity vn-computation-error-no-resource { base vn-computation-error-reason; description "VN computation has failed because there is no available resource in one or more domains."; } identity vn-computation-error-path-not-found { base vn-computation-error-reason; description "VN computation failed as no path found."; } identity vn-computation-ap-unknown { base vn-computation-error-reason; description "VN computation failed as source or destination Access Point (AP) not known."; } /* Groupings */ grouping vn-ap { description "Virtual Network Access Points (VNAP) related information"; leaf vn-ap-id { type ap-id; description "A unique identifier for the VNAP"; } leaf vn { type leafref { path "/virtual-network/vn/vn-id"; } description "A reference to the VN"; } leaf abstract-node { type leafref { path "/nw:networks/nw:network/nw:node/tet:te-node-id"; } description "A reference to the abstract node in TE Topology that represent the VN"; } leaf ltp { type leafref { path "/nw:networks/nw:network/nw:node/" + "nt:termination-point/tet:te-tp-id"; } description "A reference to Link Termination Point (LTP) in the TE-topology"; reference "RFC 8795: YANG Data Model for Traffic Engineering (TE) Topologies"; } leaf max-bandwidth { type te-types:te-bandwidth; config false; description "The max bandwidth of the VNAP"; } reference "RFC 8453: Framework for Abstraction and Control of TE Networks (ACTN), Section 6"; } grouping access-point { description "AP related information"; leaf ap-id { type ap-id; description "An AP identifier unique within the scope of the entity that controls the VN."; } leaf pe { type leafref { path "/nw:networks/nw:network/nw:node/tet:te-node-id"; } description "A reference to the PE node in the native TE Topology"; } leaf max-bandwidth { type te-types:te-bandwidth; description "The max bandwidth of the AP"; } leaf avl-bandwidth { type te-types:te-bandwidth; description "The available bandwidth of the AP"; } list vn-ap { key "vn-ap-id"; uses vn-ap; description "List of VNAP in this AP"; } reference "RFC 8453: Framework for Abstraction and Control of TE Networks (ACTN), Section 6"; } grouping vn-member { description "The vn-member is described by this grouping"; leaf vnm-id { type vnm-id; description "A vn-member identifier"; } container src { description "The source of VN Member"; leaf src { type leafref { path "/access-point/ap/ap-id"; } description "A reference to source AP"; } leaf src-vn-ap-id { type leafref { path "/access-point/ap/vn-ap/vn-ap-id"; } description "A reference to source VNAP"; } leaf multi-src { if-feature "multi-src-dest"; type boolean; default "false"; description "Is the source part of multi-source, where only one of the source is enabled"; } } container dest { description "the destination of VN Member"; leaf dest { type leafref { path "/access-point/ap/ap-id"; } description "A reference to destination AP"; } leaf dest-vn-ap-id { type leafref { path "/access-point/ap/vn-ap/vn-ap-id"; } description "A reference to dest VNAP"; } leaf multi-dest { if-feature "multi-src-dest"; type boolean; default "false"; description "Is destination part of multi-destination, where only one of the destination is enabled"; } } leaf connectivity-matrix-id { type leafref { path "/nw:networks/nw:network/nw:node/tet:te/" + "tet:te-node-attributes/" + "tet:connectivity-matrices/" + "tet:connectivity-matrix/tet:id"; } description "A reference to connectivity-matrix"; reference "RFC 8795: YANG Data Model for Traffic Engineering (TE) Topologies"; } container underlay { description "An empty container that can be augmented with underlay technology information not supported by RFC 8795 (for example - Segment Routing (SR). "; } reference "RFC 8454: Information Model for Abstraction and Control of TE Networks (ACTN)"; } grouping vn-policy { description "policy for VN-level diversity"; leaf vn-level-diversity { type te-types:te-path-disjointness; description "The type of disjointness on the VN level (i.e., across all VN members)"; } } /* Configuration data nodes */ container access-point { description "AP configurations"; list ap { key "ap-id"; description "access-point identifier"; uses access-point { description "The access-point information"; } } reference "RFC 8453: Framework for Abstraction and Control of TE Networks (ACTN), Section 6"; } container virtual-network { description "VN configurations"; list vn { key "vn-id"; description "A virtual network is identified by a vn-id"; leaf vn-id { type vn-id; description "An identifier unique within the scope of the entity that controls the VN."; } uses te-types:te-topology-identifier; leaf abstract-node { type leafref { path "/nw:networks/nw:network/nw:node/tet:te-node-id"; } description "A reference to the abstract node in TE Topology"; } list vn-member { key "vnm-id"; description "List of vn-members in a VN"; uses vn-member; leaf oper-status { type te-types:te-oper-status; config false; description "The vn-member operational state."; } leaf if-selected { if-feature "multi-src-dest"; type boolean; default "false"; config false; description "Is the vn-member is selected among the multi-src/dest options"; } } leaf admin-status { type te-types:te-admin-status; default "up"; description "VN administrative state."; } leaf oper-status { type te-types:te-oper-status; config false; description "VN operational state."; } uses vn-policy; } reference "RFC 8453: Framework for Abstraction and Control of TE Networks (ACTN)"; } /* RPC */ rpc vn-compute { description "The VN computation without actual instantiation. This is used by the CNC to get the VN results without actually creating it in the network. The input could include a reference to the single node abstract topology. It could optionally also include constraints and optimization criteria. The computation is done based on the list of VN-members. The output includes a reference to the single node abstract topology with each VN-member including a reference to the connectivity-matrix-id where the path properties could be found. Error information is also included."; input { uses te-types:te-topology-identifier; leaf abstract-node { type leafref { path "/nw:networks/nw:network/nw:node/tet:te-node-id"; } description "A reference to the abstract node in TE Topology"; } uses te-types:generic-path-constraints; leaf cos { type te-types:te-ds-class; description "The class of service"; } uses te-types:generic-path-optimization; list vn-member-list { key "vnm-id"; description "List of VN-members in a VN"; uses vn-member; uses te-types:generic-path-constraints; leaf cos { type te-types:te-ds-class; description "The class of service"; reference "RFC 4124: Protocol Extensions for Support of Diffserv-aware MPLS Traffic Engineering, Section 4.3.1"; } uses te-types:generic-path-optimization; } uses vn-policy; } output { uses te-types:te-topology-identifier; leaf abstract-node { type leafref { path "/nw:networks/nw:network/nw:node/tet:te-node-id"; } description "A reference to the abstract node in TE Topology"; } list vn-member-list { key "vnm-id"; description "List of VN-members in a VN"; uses vn-member; leaf if-selected { if-feature "multi-src-dest"; type boolean; default "false"; description "Is the vn-member is selected among the multi-src/dest options"; reference "RFC 8453: Framework for Abstraction and Control of TE Networks (ACTN), Section 7"; } leaf compute-status { type vn-compute-status; description "The VN-member compute state."; } container error-info { description "Error information related to the VN member"; leaf error-description { type string { length "1..max"; } description "Textual representation of the error occurred during VN compute."; } leaf error-timestamp { type yang:date-and-time; description "Timestamp of the attempt."; } leaf error-reason { type identityref { base vn-computation-error-reason; } description "Reason for the VN computation error."; } } } } } } ]]>
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 or RESTCONF . The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) . The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS . The NETCONF access control model 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. The model presented in this document is used in the interface between the Customer Network Controller (CNC) and Multi-Domain Service Coordinator (MDSC), which is referred to as CNC-MDSC Interface (CMI). Therefore, many security risks such as malicious attack and rogue elements attempting to connect to various ACTN components. Furthermore, some ACTN components (e.g., MDSC) represent a single point of failure and threat vector and must also manage policy conflicts and eavesdropping of communication between different ACTN components. 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:
  • ap: this list includes a set of sensitive data that influences how the access points in the VN service are attached. By accessing the following data nodes, an attacker may be able to manipulate the VN.
    • ap-id
    • max-bandwidth
    • avl-bandwidth
  • vn-ap: this list includes a set of sensitive data that influences how the VN service is delivered. By accessing the following data nodes, an attacker may be able to manipulate the VN.
    • vn-ap-id
    • vn
    • abstract-node
    • ltp
  • vn: this list includes a set of sensitive data that influences how the VN service is delivered. By accessing the following data nodes, an attacker may be able to manipulate the VN.
    • vn-id
    • vn-topology-id
    • abstract-node
  • vn-member: this list includes a set of sensitive data that influences how the VN member in the VN service is delivered. By accessing the following data nodes, an attacker may be able to manipulate the VN member.
    • vnm-id
    • src
    • src-vn-ap-id
    • dest
    • dest-vn-ap-id
    • connectivity-matrix-id
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:
  • oper-status: this leaf can reveal the current operational state of the VN.
  • if-selected: this leaf can reveal which vn-member is selected among the various multi-src/dest options.
Some of the RPC operations in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control access to these operations. These are the operations and their sensitivity/vulnerability:
  • vn-compute: this rpc triggers the VN computation at the MDSC which can reveal the VN information.
IANA Considerations IANA is requested to make the following allocation for the URIs in the "ns" subregistry within the "IETF XML Registry" : IANA is requested to make the following allocation for the YANG module in the "YANG Module Names" registry :
Acknowledgments The authors would like to thank Xufeng Liu, Adrian Farrel, Tom Petch, Mohamed Boucadair, Italo Busi, Bo Wu and Daniel King for their helpful comments and valuable suggestions. Thanks to Andy Bierman for YANGDIR review. Thanks to Darren Dukes for RTGDIR review. Thanks to Behcet Sarikaya for GENART review. Thanks to Deb Cooley for IESG review.
References Normative References Informative References
Performance Constraints At the time of creation of VN, it is natural to provide VN level constraints and optimization criteria. It should be noted that this YANG module relies on the TE-Topology Model by using a reference to an abstract node to achieve this. Further, connectivity-matrix structure is used to assign the constraints and optimization criteria include delay, jitter etc. defines some of the metric-types already and future documents are meant to augment it. Note that the VN compute allows inclusion of the constraints and the optimization criteria directly in the RPC to allow it to be used independently.
JSON Example
VN JSON This section provides JSON examples as to how VN YANG model and TE topology model are used together to instantiate VN. The example in this section includes following VN
  • VN1 (Type 1): Which maps to the single node topology abstract1 and consist of VN Members 104 (L1 to L4), 107 (L1 to L7), 204 (L2 to L4), 308 (L3 to L8) and 108 (L1 to L8).
  • VN2 (Type 2): Which maps to the single node topology abstract2, this topology has an underlay topology (called underlay). This VN has a single VN member 105 (L1 to L5) and an underlay path (S4 and S7) has been set in the connectivity matrix of abstract2 topology;
  • VN3 (Type 1): This VN has a multi-source and multi-destination feature enabled. VN Member 106 (L1 to L6) and 107 (L1 to L7) showcase multi-dest and VN Member 108 (L1 to L8) and 308 (L3 to L8) showcase multi-src feature. The selected VN-member is known via the field "if-selected" and the corresponding connectivity-matrix-id.
Note that the VN YANG model also include the AP and VNAP which shows various VN using the same AP.
TE-topology JSON This section provides JSON examples of the various TE topology instances. The example in this section includes following TE Topologies
  • abstract1: a single node TE topology referenced by VN1. We also show how disjointness (node, link, srlg) is supported in the example on the connectivity matrices.
  • abstract2: a single node TE topology referenced by VN2 with underlay path.
  • underlay: the topology with multiple nodes (in the underlay path of abstract2). For brevity, the example includes only the node and other parameters are not included.
  • abstract3: a single node TE topology referenced by VN3.
Contributors Addresses