NETMOD Working Group N. Sambo Internet-Draft P. Castoldi Intended status: Standards Track Scuola Superiore Sant'Anna Expires: November 22, 2019 G. Fioccola Huawei Technologies F. Cugini CNIT H. Song T. Zhou Huawei May 21, 2019 YANG model for finite state machine draft-sambo-netmod-yang-fsm-05 Abstract Network operators and service providers are facing the challenge of deploying systems from different vendors while looking for a trade- off among transmission performance, network device reuse, and capital expenditure without the need of being tied to single vendor equipment. The deployment and operation of more dynamic and programmable network infrastructures can be driven by adopting model- driven and software-defined control and management paradigms. In this context, YANG enables to compile a set of consistent vendor- neutral data models for networks and components based on actual operational needs emerging from heterogeneous use cases. This document proposes YANG models to describe events, operations, and finite state machine of YANG-defined network elements. The proposed models can be applied in several use cases: i) in the context of optical networks to pre-instruct data plane devices (e.g., an optical transponder) on the actions to be performed (e.g., code adaptation) in case some events, such as physical layer degradations, occur; ii) in general data networks, network telemetry applications can define and embed custom data probes into data plane devices. A probe in many cases can be modeled as an FSM; iii) the monitoring of packet loss and delay through a network clustering approach; iv) for re- routing in optical networks. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute Sambo, et al. Expires November 22, 2019 [Page 1] Internet-Draft YANG for FSM May 2019 working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on November 22, 2019. 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 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 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions used in this document . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Example of application . . . . . . . . . . . . . . . . . . . 4 4.1. Pre-programming resiliency schemes in EONs . . . . . . . 4 4.2. Deploying Dynamic Probes for Programmable Network Telemetry . . . . . . . . . . . . . . . . . . . . . . . . 8 4.3. IP Performance Measurements on multipoint-to-multipoint large Networks . . . . . . . . . . . . . . . . . . . . . 10 4.4. Re-routing in optical networks . . . . . . . . . . . . . 11 5. YANG for finite state machine (FSM) . . . . . . . . . . . . . 12 6. Implementation of the pre-programming resiliency schemes in EONs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 7. Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7.1. YANG model for FSM - Tree . . . . . . . . . . . . . . . . 16 7.2. YANG model for FSM - Code . . . . . . . . . . . . . . . . 16 7.3. Example of values for the YANG model . . . . . . . . . . 29 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 30 9. Other Contributors . . . . . . . . . . . . . . . . . . . . . 30 10. Security Considerations . . . . . . . . . . . . . . . . . . . 31 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 31 Sambo, et al. Expires November 22, 2019 [Page 2] Internet-Draft YANG for FSM May 2019 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 31 12.1. Normative References . . . . . . . . . . . . . . . . . . 31 12.2. Informative References . . . . . . . . . . . . . . . . . 31 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32 1. Introduction Networks are evolving toward more programmability, flexibility, and multi-vendor interoperability. Multi-vendor interoperability can be applied in the context of nodes, i.e. a node composed of components provided by different vendors (named fully disaggregated white box) is assembled under the same control system. This way, operators can optimize costs and network performance without the need of being tied to single vendor equipment. NETCONF protocol RFC6241 [RFC6241] based on YANG data modeling language RFC6020 [RFC6020] is emerging as a candidate Software Defined Networking (SDN) enabled protocol. First, NETCONF supports both control and management functionalities, thus permits high programmability. Then, YANG enables data modeling in a vendor-neutral way. Some recent works have provided YANG models to describe attributes of links (e.g., identification), nodes (e.g., connectivity matrix), media channels, and transponders (e.g., supported forward error correction - FEC) of networks ([I-D.ietf-i2rs-yang-network-topo] [I-D.vergara-ccamp-flexigrid-yang] [I-D.zhang-ccamp-l1-topo-yang]), also including optical technologies. This document presents YANG models to describe events, operations, and finite state machine of YANG-defined network elements. Such models can be applied to several use cases. In the context of elastic optical networks (EONs), the model enables a centralized remote network controller (managed by a network operator) to instruct a transponder controller about the actions to perform when certain events (e.g., failures) occur. The actions to be taken and the events can be re-programmed on the device. In general data networks, programmable network telemetry is considered a killer SDN application which can help applications gain unprecedented visibility to network data plane. Instead of providing raw data, network devices can be configured to filter and process data directly on the data plane and only hand preprocessed data to the collector, in order to save data bandwidth and reduce reaction delay ([I-D.song-opsawg-dnp4iq]) . Such configurations can be programed as custom probes and dynamically deployed into data plane devices. A probe in many cases can be modeled as an FSM. Another use case is the monitoring of packet loss and delay through a network clustering approach: in this case, each FSM state is determined by a specific subdivision of the network in Clusters ([I-D.ietf-ippm-multipoint-alt-mark]). Finally, a use case is related to enable automatic local reconfiguration of a backup route in optical networks. Sambo, et al. Expires November 22, 2019 [Page 3] Internet-Draft YANG for FSM May 2019 2. Conventions used in this document 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 RFC2119 [RFC2119]. 3. Terminology ABNO: Application-Based Network Operations BER: Bit Error Rate EON: Elastic Optical Network FEC: Forward Error Correction FSM: Finite State Machine NETCONF: Network Configuration Protocol OAM: Operation Administration and Maintenance SDN: Software Defined Network YANG: Yet Another Network Generator DNP: Dynamic Network Probe AMM: Alternate Marking Method 4. Example of application 4.1. Pre-programming resiliency schemes in EONs EONs (optical networks based on flexible grid supporting circuits of different bandwidth) are expected to employ flexible transponders, i.e. transponders supporting multiple bit rates, multiple modulation formats, and multiple codes. Such transponders permits the (re-) configuration of the bit rate value based on traffic requirements, as well as the configuration of the modulation format and code based on the physical characteristics of a path (e.g., quadrature phase shift keying is more robust than 16 quadrature amplitude modulation). This way, transmission parameters can be (re-) configured based on physical layer changes. The YANG model presented in this draft enables to pre-program reconfiguration settings of data plane devices in case of failures or physical layer degradations. In particular, soft failures are assumed. Soft failures imply transmission performance degradation, in turns a bit error rate (BER) increase, Sambo, et al. Expires November 22, 2019 [Page 4] Internet-Draft YANG for FSM May 2019 e.g. due to the ageing of some network devices. Without loosing generality, the ABNO architecture is assumed for the control and management of EONs (RFC7491 [RFC7491]). Considering the state of the art, when pre-FEC BER passes above a predefined threshold, it is expected that an alarm is sent to the OAM Handler, which communicates with the ABNO controller that may trigger an SDN controller (that could be the Provisioning Manager of ABNO RFC7491 [RFC7491]) for computing new transmission parameters. The involved ABNO modules are shown in the simplified ABNO architecture of Fig. 1. Then, transponders are reconfigured. When alarms related to several connections impacted by the soft failure are generated, this procedure may be particularly time consuming. The related workflow for transponder reconfiguration is shown in Fig. 2. The proposed model enables an SDN controller to instruct the transponder about reconfiguration of new transmission parameters values if a soft failure occurs. This can be done before the failure occurs (e.g., during the connection instantiation phase or during the connection service), so that data plane devices can promptly reconfigure themselves without querying the SDN controller to trigger an on- demand recovery. This is expected to speed up the recovery process from soft failures. The related flow chart is shown in Fig. 3. The whole mechanism is based on a finite state machine where each state is associated to a specific configuration of transmission parameters (e.g., modulation format). The transition from a state to another state is triggered by specific events at the physical layer such as the bit error rate above a threshold. The transition from a state to another state implies a set of actions, including the change of transmission parameters (e.g., modulation format), which are actually suitable for the current condition at the physical layer. Moreover, since transmission and receiver must be synchronized about the transmission settings (modulation format and so no) for a proper transmission, another action consists of this synchronization. Thus, when the transponder at the receiver side decides to change its transmission parameters based on the monitored BER, the remote transponder at the transmitter side has to do the same state transition. In particular, the transponder at the receiver side sends a message to the transmitter to synchronize about the transmission parameters to be adopted. This message can be sent over a control channel. This way both the transmitter and receiver operates with the same transmission parameters: e.g. the format, FEC, and so on. No central controller is involved at this stage, only a notification can be sent to the central controller to inform it about the successful reconfiguration. Sambo, et al. Expires November 22, 2019 [Page 5] Internet-Draft YANG for FSM May 2019 ___________ ___________ | ABNO | | OAM | |controller | ------ | Handler | |___________| |___________| | | | | | | ____________ | | SDN | | | controller | | |____________| | | | | | | | | _____________________________ | Client | | network | |_____________________________| Figure 1: Assumed ABNO functional modules Sambo, et al. Expires November 22, 2019 [Page 6] Internet-Draft YANG for FSM May 2019 _____________________ | 1 | |Sending alarm to the | | OAM Handler | | | |_____________________| | | | _____________________ | 2 | | Trigger | | SDN Controller | | | |_____________________| | | | _____________________ | 3 | | Computation of | | new transmission | | parameters | |_____________________| | | | _____________________ | 4 | | Data plane | | reconfiguration | | | |_____________________| Figure 2: Flow chart of the expected state-of-the-art approach Sambo, et al. Expires November 22, 2019 [Page 7] Internet-Draft YANG for FSM May 2019 _______________________ | 1 | | Instructing the local | | controller of | | data plane devices | |_______________________| | | | _______________________ | 2 | | Local reconfiguration | | upon failure | | detection | |_______________________| | | | _______________________ | 3 | | | | notification | | | |_______________________| Figure 3: Flow chart of the approach exploiting YANG models in this draft 4.2. Deploying Dynamic Probes for Programmable Network Telemetry In the past, network data analytics was considered a separate function from networks. They consume raw data extracted from networks through piecemeal protocols and interfaces. With the advent of user programmable data plane, we expect a paradigm shift that makes the data plane be an active component of the data telemetry and analytics solution. The programmable in-network data preprocessing is efficient and flexible to offload some light-weight data processing through dynamic data plane programming or configuration. A universal network data analytics platform built on top of this enables a tight and agile network control and OAM feedback loop. A proposed dynamic network telemetry system architecture is illustrated in Fig.4. An application translates its data requirements into a set of Dynamic Network Probes (DNP) targeting a subset of data plane devices. After the probes are deployed, each probe conducts its corresponding in- network data preprocessing and feeds the preprocessed data to the Sambo, et al. Expires November 22, 2019 [Page 8] Internet-Draft YANG for FSM May 2019 collector. The collector finishes the data post-processing and presents the results to the data-requesting application. +-------------------------------------+ | network telemetry applications | +-------------------------------------+ ^ | | V | +--------------------+ | | DNP compile/config | | +--------------------+ | | | V +---------------+ +--------------------+ |data collection| | Probe deployment | +---------------+ +--------------------+ ^ ^ ^ | | | | | | V V V +--------------------------------------+ | network data plane devices | | (in-network data preprocessing) | +--------------------------------------+ Figure 4: Deploy dynamic network probes using YANG FSM models Many DNPs can be modeled as FSM which are configured to capture specific events. Here FSMs essentially preprocess the raw stream data and only report the necessary data to subscribing applications. For example, a congestion control application needs to monitor the router buffer occupancy. Instead of polling the buffer depth periodically, it is only interested in the real-time events when the buffer depth crosses a low and a high threshold. We can install a probe to achieve this data plane function and the probe can be modeled as a three-state FSM. Each state represents a buffer region: below the low threshold, above the high threshold, and in between the two thresholds. A possible state transition is checked against the buffer depth for each incoming and outgoing packet. Whenever a state transition happens, an event is generated and reported to the application. This approach significantly reduces the amount of data sent to the application and also allows a timely event notification. For another example, an application would like to monitor the delay experienced by a flow. The packet delay on its forwarding path can be acquired by using iOAM [I-D.brockners-inband-oam-requirements]. However, the application only needs to know that N consecutive flow packets experience a delay longer than T. Instead of forwarding the Sambo, et al. Expires November 22, 2019 [Page 9] Internet-Draft YANG for FSM May 2019 raw delay data to the application, a probe can be deployed to detect the event. Similarly, the probe can be modeled as an FSM. 4.3. IP Performance Measurements on multipoint-to-multipoint large Networks Networks offer rich sets of network performance measurement data, but traditional approaches run into limitations. One reason for this is the fact that in many cases, the bottleneck is the generation and export of the data and the amount of data that can be reasonably collected from the network runs into bandwidth and processing constraints in the network itself. In addition, management tasks related to determining and configuring which data to generate lead to significant deployment challenges. In order to address these issues, an SDN controller application orchestrates network performance measurements tasks across the network to allow an optimized monitoring. In fact the IP Performance Measurement SDN Controller Application in Figure 5 can calibrate how deep can be obtained monitoring data from the network by configuring measurement points roughly or meticulously. This can be established by using the feedback mechanism reported in Figure 5. For instance, the SDN Controller can configure initially an end to end monitoring between ingress points and egress points of the network. If the network does not experiment issues, this approximate monitoring is good enough and is very cheap in terms of network resources. But, in case of problems, the SDN Controller becomes aware of the issues from this approximate monitoring and, in order to localize the portion of the network that has issues, configures the measurement points more exhaustively. So a new detailed monitoring is performed. After the detection and resolution of the problem the initial approximate monitoring can be used again. This idea is general and can be applied to different performance measurements techniques both active and passive (and hybrid). +--------------------------------------+ | IP Performance Measurement | | SDN Controller Application | +--------------------------------------+ ^ ^ ^ | | | | | | v v v +--------------------------------------+ | Multipoint Network | +--------------------------------------+ Figure 5: Feedback mechanism on multipoint-to-multipoint large Networks Sambo, et al. Expires November 22, 2019 [Page 10] Internet-Draft YANG for FSM May 2019 One of the most efficient methodology to perform packet, loss delay and jitter measurements both in an IP and Overlay Networks is the Alternate Marking method, as presented in RFC8321 [RFC8321] and [I-D.ietf-ippm-multipoint-alt-mark]. This technique can be applied to point-to-point flows but also to multipoint.to-multipoint flows (see RFC8321 [RFC8321] and [I-D.ietf-ippm-multipoint-alt-mark]). The Alternate Marking method creates batches of packets by alternating the value of 1 or 2 bits of the packet header. These batches of packets are unambiguously recognized over the network and the comparison of packet counters permits the packet loss calculation. The same idea can be applied for delay measurement by selecting special packets with a marking bit dedicated for delay measurements. This method needs two counters each marking period for each flow under monitor. For this reason by considering n measurement points and n monitored flows, the order of magnitude of the packet counters for each time interval is n*n*2 (1 per color). Multipoint Alternate Marking, described in [I-D.ietf-ippm-multipoint-alt-mark], aims to reduce this value and makes the performance monitoring more flexible in case a detailed analysis is not needed. It is possible to monitor a Multipoint Network without examining in depth by using the Network Clustering (subnetworks that are portions of the entire network that preserve the same property of the entire network). So in case there is packet loss or the delay is too high the filtering criteria could be specified more in order to perform a per flow detailed analysis, as described in RFC8321 [RFC8321]. An application of the multipoint performance monitoring can be done by using FSM (each state is a composition of clusters) and feedback mechanism where the SDN Controller is the brain of the network and can manage flow control to the switches and routers and, in the same way, can calibrate the performance measurements depending on the necessity. 4.4. Re-routing in optical networks FSM can be also applied for rerouting purposes as dynamic restoration in optical networks. In such a use case all the nodes along the backup route of a media channel should hold a FSM indicating the reconfigurations to be performed in case that media channel is rerouted along the backup path. Note that resources along the backup route are not reserved neither configured during a normal operation of the network as instead it happens for protection. Sambo, et al. Expires November 22, 2019 [Page 11] Internet-Draft YANG for FSM May 2019 The proposed approach aims at achieving a sort of hybrid centralized/ distributed rerouting solution applicable to all the networks controlled with NETCONF. More specifically, the decision of the backup route is taken centrally by the SDN controller, but it is acted in a distributed way through FSM when a problem appears. In particular, the transmitter, the receiver, and the ROADMs along the backup route have installed in their agent a FSM including a "re- routing" state, associated to a specific media channel. For the transmitter and receiver, this state is associated to the transmission parameters of the backup media channel: e.g., modulation format, central frequency, FEC, and so on. Regarding the ROADMs, the "re-routing" state is associated to the cross connections of the backup route. When a link failure occurs (e.g., fiber cut), the receiver reveals a loss of light, which triggers the transition to the "re-routing" state. Thus, the receiver can set itself to the new transmission parameters. Moreover, similarly to the message sent over a control channel to the transmitter in Sec. 4.1, the receiver sends a message to the transmitter and the backup Reconfigurable Add-Drop Multiplexer (ROADMs). The task of this message is to simply trigger a state transition to the "re-routing" state so that each backup ROADM and the transmitter can apply the proper reconfigurations. This way, the SDN controller is not interrogated during the failure and the recovery can be speeded up. After reconfigurations, the SDN controller can be notified and the SDN controller can tear down the primary path. Backup routes can be reprogrammed based on the network states evolutions (e.g., link and spectrum occupancy). 5. YANG for finite state machine (FSM) This model defines a list of states and transitions to describe a generic finite state machine (FSM). The related code and tree are shown in the Appendix. : it defines the current state of the FSM. : this element defines the FSM as follows. : this list defines all the FSM states. : this leaf attribute of defines the identifier of the state : this leaf attribute of defines the name of the state : this leaf is a "string" describing the state : this attribute defines a list of transitions to other states in the FSM. : this attribute defines the name of a Sambo, et al. Expires November 22, 2019 [Page 12] Internet-Draft YANG for FSM May 2019 transition : this attribute defines the type of the transition from a pool of possible transition types predefined inside the YANG model. Together with the attribute, it uniquely identifies the transition. : this optional attribute is a "string" describing the transition : this leaf is a list of input parameters related to the transition. This attribute enables to further express a transition: as an example, if a transition can be triggered by a parameter (e.g., a monitored performance parameter) exceeding a threshold (as in Sec. 5), an element of the list defines this threshold. Thus, if the parameter is outside the threshold, the transition is taken, otherwise not. : this leaf of defines a filter parameter. : this leaf of define the identifier number associated with the attribute. : this attribute defines a list of actions to take during the transition. : this attribute is the list of actions : this leaf of defines the identifier number of an action. : this leaf of defines the type of an action. : this leaf defines (differently from detailed below) an action that has to be directly executed. : this attribute recalls an RPC encapsulating the effective task (action) to be executed by the hardware. If more actions (e.g., "A" and "B"), defined in the list, have to be executed, these actions can be executed sequentially according to the attribute detailed below. Thus, by Sambo, et al. Expires November 22, 2019 [Page 13] Internet-Draft YANG for FSM May 2019 referring to the tree of the Appendix, when an action ("A") is executed, the attribute will bring to another action ("B"). If more actions have to be executed in parallel (e.g., "A" & "B"), not sequentially, an element of the list should be defined to express an action (e.g., "A&B") consisting of more actions to be executed in parallel. : this attribute defines the identification number of a next action that has to be taken. The can assume a NULL value. : this leaf enables a check ("true" or "false") to be verified before executing the action. Based on the check, the proper attributes and are considered. : this leaf of defines the condition to be verified before executing the action. : this leaf of defines a result of the check associated to . Proper and attributes are associated with this result of the check. : this leaf of defines a result of the check associated to . Proper and Sambo, et al. Expires November 22, 2019 [Page 14] Internet-Draft YANG for FSM May 2019 attributes are associated with this result of the check. : this attribute defines the next state of FSM when an action is executed. 6. Implementation of the pre-programming resiliency schemes in EONs These presented model can be used to enable a centralized network controller, managed by a network operator, to instruct data plane hardware on its reconfiguration if some events, such as a failure or physical layer degradation, occur. As an example, an optical signal impacted by a soft failure (i.e., a physical layer degradation inducing a pre forward error correction bit error rate increase - pre-FEC) can be maintained by adapting the FEC of the signal itself. This action to be taken and, more in general operations to be executed depending on critical events, can be (re-) programmed on the transponder by (re-) sending a NETCONF message to the device controller including a FSM defined by the YANG model. Such a system has the main goal to speed up the reaction of the network to certain events/faults and to alleviate the workload of the centralized controller. The speed up derives from the fact that the centralized controller is able to pre-compute and pre-configure on the network devices the actions to take when an event occurs taking into account a global view and knowledge of the network. In this way, the device is already aware of the actions to be locally applied to reconfigure a connection, avoiding to inform the controller and to wait for the response indicating what to do. Consequently, part of the workload is also removed from the centralized controller. When the reaction is successfully completed in the data plane, the centralized controller can be notified about the faults and the taken action. A flexible transponder supporting two FEC types, 7% and 20%, is considered. A two-states FSM is also assumed. The states have attribute set to "Steady" and "Fec-Baud-Adapt", respectively. In the "Steady" state, the signal is in a healthy condition, adopting a 7% FEC, with a pre-FEC BER below an assigned threshold of 9 x 10-4. A transition from this state can be triggered by the event with =BER_CHANGE and =9 x 10-4, thus expressing a change of the pre-FEC BER above the threshold. In case the pre-FEC BER exceeds 9 x 10-4 due to a soft failure, the state machine evolves to the "Fec-Baud-Adapt" state and an adaptation to a more robust FEC of 20% (executed by the attribute ) is performed. The system can return to the "Steady" state if the pre-FEC BER goes below another pre-defined threshold and the FEC is reconfigured to 7%. Sambo, et al. Expires November 22, 2019 [Page 15] Internet-Draft YANG for FSM May 2019 7. Appendix This appendix reports the YANG models code and the related tree. 7.1. YANG model for FSM - Tree module: ietf-fsm +--rw current-state? leafref +--rw states +--rw state [id] +--rw id state-id-type +--rw description? string +--rw transitions +--rw transition [name type] +--rw name string +--rw type transition-type +--rw description? string +--rw filters | +--rw filter [filter-id] | +--rw filter-id uint32 +--rw actions +--rw action [id] +--rw id transition-id-type +--rw type enumeration +--rw conditional | +--rw statement string | +--rw true | | +--rw execute | | +--rw next-action? transition-id-type | | +--rw next-state? leafref | +--rw false | +--rw execute | +--rw next-action? transition-id-type | +--rw next-state? leafref +--rw simple +--rw execute +--rw next-action? transition-id-type +--rw next-state? leafref 7.2. YANG model for FSM - Code file "ietf-fsm@2016-03-15.yang" module ietf-fsm { namespace "http://sssup.it/fsm"; Sambo, et al. Expires November 22, 2019 [Page 16] Internet-Draft YANG for FSM May 2019 prefix fsm; identity TRANSITION { description "Base for all types of event"; } identity ON_CHANGE { base TRANSITION; description "The event when the database changes."; } // typedef statements typedef transition-type { description "it defines the type of transition (event)"; type identityref { base TRANSITION; } } typedef transition-id-type { description "it defines the id of the transition (event)"; Sambo, et al. Expires November 22, 2019 [Page 17] Internet-Draft YANG for FSM May 2019 type uint32; } // grouping statements grouping action-block { description "it defines the action to perform when a transition occurs"; leaf id { description "it refers to the id of the transition"; type transition-id-type; } leaf type { description "it defines if the action has to be simply executed or if a conditional statement has to be checked before execution"; type enumeration { enum "CONDITIONAL_OP" { description "it defines the type CONDITIONAL OPERATION to check a statement before execution"; } enum "SIMPLE_OP" { description "it defines the type SIMPLE OPERATION: i.e., an operation to be directly executed; } } mandatory true; } grouping execution-top { Sambo, et al. Expires November 22, 2019 [Page 18] Internet-Draft YANG for FSM May 2019 description "it defines the execution attribute"; anyxml execute { description "Represent the action to perform"; } leaf next-action { type transition-id-type; description "the id of the next action to execute"; } } container conditional { description "it defines the container CONDITIONAL"; when "../type = 'CONDITIONAL_OP'"; leaf statement { type string; mandatory true; description "The statement to be evaluated before execution. E.g. if a=b"; } container true { description "it is referred to the result TRUE of a conditional statement"; uses execution-top; Sambo, et al. Expires November 22, 2019 [Page 19] Internet-Draft YANG for FSM May 2019 } container false { description "it is referred to the result FALSE of a conditional statement "; uses execution-top; } } container simple { description "Simple execution of an action without checking any condition"; when "../type = 'SIMPLE_OP'"; uses execution-top; } } grouping action-top { description "it defines the grouping of action"; list action { description "it defines the list of actions"; key "id"; ordered-by user; uses action-block; } Sambo, et al. Expires November 22, 2019 [Page 20] Internet-Draft YANG for FSM May 2019 } grouping on-change { description "Event occuring when a modification of one or more objects occurs"; container filters { description "This container contains a list of configurable filters that can be applied to subscriptions. This facilitates the reuse of complex filters once defined."; list filter { key "filter-id"; description "A list of configurable filters that can be applied to subscriptions."; leaf filter-id { type uint32; description "An identifier to differentiate between filters."; } } } Sambo, et al. Expires November 22, 2019 [Page 21] Internet-Draft YANG for FSM May 2019 } grouping transition-top { description "it defines the grouping transition"; leaf name { description "it defines the transition name"; type string; mandatory true; } leaf type { description "it defines the transition type"; type transition-type; mandatory true; } leaf description { description "it describes the transition "; type string; } // list of all possible events uses on-change { Sambo, et al. Expires November 22, 2019 [Page 22] Internet-Draft YANG for FSM May 2019 when "type = 'ON_CHANGE'"; } container actions { description "it defines the container action"; uses action-top; } } grouping transitions-top { description "it defines the grouping transition"; container transitions { description "it defines the container transitions"; list transition { description "it defines the list of transitions"; key "name type"; uses transition-top; } } } // data definition statements Sambo, et al. Expires November 22, 2019 [Page 23] Internet-Draft YANG for FSM May 2019 uses transitions-top; // extension statements // feature statements // augment statements organization "Scuola Superiore Sant'Anna Network and Services Laboratory"; contact " Editor: Matteo Dallaglio "; description "This module contains a YANG definitions of a generic finite state machine."; revision 2016-03-15 { description "Initial Revision."; reference "RFC xxxx:"; Sambo, et al. Expires November 22, 2019 [Page 24] Internet-Draft YANG for FSM May 2019 } // identity statements // typedef statements typedef state-id-type { description "it defines the id type of the states"; type uint32; } // grouping statements grouping state-top { description "it defines the grouping state"; leaf id { description "it defines the id of a transition"; type state-id-type; } leaf description { description "it describes a transition"; type string; Sambo, et al. Expires November 22, 2019 [Page 25] Internet-Draft YANG for FSM May 2019 } grouping next-state-top { description "it defines the grouping for the next state"; leaf next-state { description "it defines the next state"; type leafref { description "it refers to its id"; path "../../../../../../../../../states/state/id"; } description "Id of the next state"; } } uses transitions-top { augment "transitions/transition/actions/action/conditional/true" { uses next-state-top; } augment "transitions/transition/actions/action/conditional/false" { Sambo, et al. Expires November 22, 2019 [Page 26] Internet-Draft YANG for FSM May 2019 uses next-state-top; } augment "transitions/transition/actions/action/simple" { //uses next-state-top; leaf next-state { description "it defines the next state"; type leafref { description "it refers to its id"; path "../../../../../../../../states/state/id"; } description "Id of the next state"; } } } } grouping states-top { description "it defines the grouping states"; leaf current-state { description "it defines the current state"; type leafref { Sambo, et al. Expires November 22, 2019 [Page 27] Internet-Draft YANG for FSM May 2019 description "it refers to its id"; path "../states/state/id"; } } container states { description "it defines the container states"; list state { description "it defines the list of states"; key "id"; uses state-top; } } } // data definition statements uses states-top; // extension statements // feature statements Sambo, et al. Expires November 22, 2019 [Page 28] Internet-Draft YANG for FSM May 2019 // augment statements. // rpc statements }//module fsm 7.3. Example of values for the YANG model Sambo, et al. Expires November 22, 2019 [Page 29] Internet-Draft YANG for FSM May 2019 FIELD NAME | YANG DATA TYPE | VALUE _________________|_____________________|________________________ Current State | leafref | "an existing state id | | in the FSM" | | State | | id | uint32 | 1 name | string | Steady description | string | "whatever string" | | transition | | name | string | "whatever string" type | enum | BER_CHANGE description | string | "whatever string" | | filter | | filter-id | uint32 | 2 filter-type | anyxml or xpath | BER>0.0009 | | action | | id | uint32 | 3 type | enum | SIMPLE statement | string | "whatever string" execute | anyxml | "this recalls an RPC | | where the FEC value | | is expressed" next-operation | uint32 | NULL next-state | leafref | "an existing state id | | in the FSM" 8. Acknowledgements This work has been partially supported by the European Commission through the H2020 ORCHESTRA (Optical peRformanCe monitoring enabling dynamic networks using a Holistic cross-layEr, Self-configurable Truly flexible approach, grant agreement no: H2020-645360) project. The views expressed here are those of the authors only. The European Commission is not liable for any use that may be made of the information in this document. 9. Other Contributors Matteo Dallaglio (Scuola Superiore Sant'Anna), Andrea Di Giglio (Telecom Italia), Giacomo Bernini (Nextworks). Sambo, et al. Expires November 22, 2019 [Page 30] Internet-Draft YANG for FSM May 2019 10. Security Considerations TBD 11. IANA Considerations TBD 12. References 12.1. 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, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [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, . [RFC7491] King, D. and A. Farrel, "A PCE-Based Architecture for Application-Based Network Operations", RFC 7491, DOI 10.17487/RFC7491, March 2015, . 12.2. Informative References [I-D.brockners-inband-oam-requirements] Brockners, F., Bhandari, S., Dara, S., Pignataro, C., Gredler, H., Leddy, J., Youell, S., Mozes, D., Mizrahi, T., Lapukhov, P., and r. remy@barefootnetworks.com, "Requirements for In-situ OAM", draft-brockners-inband- oam-requirements-03 (work in progress), March 2017. [I-D.ietf-i2rs-yang-network-topo] Clemm, A., Medved, J., Varga, R., Bahadur, N., Ananthakrishnan, H., and X. Liu, "A Data Model for Network Topologies", draft-ietf-i2rs-yang-network-topo-20 (work in progress), December 2017. Sambo, et al. Expires November 22, 2019 [Page 31] Internet-Draft YANG for FSM May 2019 [I-D.ietf-ippm-multipoint-alt-mark] Fioccola, G., Cociglio, M., Sapio, A., and R. Sisto, "Multipoint Alternate Marking method for passive and hybrid performance monitoring", draft-ietf-ippm- multipoint-alt-mark-01 (work in progress), March 2019. [I-D.song-opsawg-dnp4iq] Song, H. and J. Gong, "Requirements for Interactive Query with Dynamic Network Probes", draft-song-opsawg-dnp4iq-01 (work in progress), June 2017. [I-D.vergara-ccamp-flexigrid-yang] Madrid, U., Perdices, D., Lopezalvarez, V., Dios, O., King, D., Lee, Y., and G. Galimberti, "YANG data model for Flexi-Grid Optical Networks", draft-vergara-ccamp- flexigrid-yang-06 (work in progress), January 2018. [I-D.zhang-ccamp-l1-topo-yang] zhenghaomian@huawei.com, z., Fan, Z., Sharma, A., and X. Liu, "A YANG Data Model for Optical Transport Network Topology", draft-zhang-ccamp-l1-topo-yang-07 (work in progress), April 2017. [RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli, L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi, "Alternate-Marking Method for Passive and Hybrid Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321, January 2018, . Authors' Addresses Nicola Sambo Scuola Superiore Sant'Anna Via Moruzzi 1 Pisa 56124 Italy Email: nicola.sambo@sssup.it Piero Castoldi Scuola Superiore Sant'Anna Via Moruzzi 1 Pisa 56124 Italy Email: piero.castoldi@sssup.it Sambo, et al. Expires November 22, 2019 [Page 32] Internet-Draft YANG for FSM May 2019 Giuseppe Fioccola Huawei Technologies Riesstrasse, 25 Munich 80992 Germany Email: giuseppe.fioccola@huawei.com Filippo Cugini CNIT Via Moruzzi 1 Pisa 56124 Italy Email: filippo.cugini@cnit.it Haoyu Song Huawei 2330 Central Expressway Santa Clara, CA 95050 USA Email: haoyu.song@huawei.com Tianran Zhou Huawei 156 Beiqing Road Beijing 100095 China Email: zhoutianran@huawei.com Sambo, et al. Expires November 22, 2019 [Page 33]