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Agenda plan of April 12, 13 and 15 ONF OTCC TAPI Meeting

CST 7pm - 12am
CEST 1pm - 6pm
BST 12pm - 5pm
EDT 7am - 12pm
PDT 4am - 9am

EDT SlotsCEST slots

P1 (07:00 – 08:45)

P1 (13:00 – 14:45)

P2 (9:00 – 10:45)

P2 (15:00 – 16:45)

P3 (11:00 – 12:00)

P3 (17:00 – 18:00)

Discussion items

Main source is tbd

DayPeriodTopic & Contributions

TAPI Version

Discussion - pls add link to contributionsNotes
Mon 12P1.1Intro, Agenda review

Agenda agreed.

Ramon Casellas is reviewing the minutes of past TAPI calls: some of the new Use Cases of draft RIA 1.1 need further review, to be planned in the next TAPI calls.


Path Computation / Planning / Check Service Feasibility (providing an Explicit Route Object)

Fully Explicit Route indication


2.3 -->

Ramon Casellas presents otcc2021.RC.001_TAPI-PathComputation.pptx

  • Learning from IETF PCE
  • Issue of UUIDs instead of object ref:

  • Karthik Sethuraman this is likely only historical, we can amend with usual object references, e.g.

grouping path-ref {
        leaf path-uuid {
            type leafref {
                path '/tapi-common:context/tapi-path-computation:path-computation-context/tapi-path-computation:path/tapi-path-computation:uuid';
            description "none";
        description "none";

  • Ramon Casellas proposes to specify in the RIA 1.1 two name-value pairs which allow to group PathComputationService concurrent provisioning:

  • It is possible to define an agreement between client and server that the Path Computation task is composed by N distinct Paths, implemented through N PathComputationService requests with a common group id and the index.
    • This solution does not conform to the protocol, but is doable in TAPI 2.1.3
    • Nigel Davis will present the PathSet concept as more generic mechanism to group Paths, see next P2 slot.
    • Karthik Sethuraman In MEF and TMF there is the concept of Order, which purpose is to track the provisioning activity.
  • ERO Provisioning:
    • Proposed the solution to specify the ConnectivityService / Path constraints as an
      • ordered set of NEPs (referenced by name),
      • per each NEP a new data structure (allocation) which includes technology specific constraints, e.g. wavelength, amplifier gain/tilt, etc:

  • Andrea Mazzini we should try to avoid model duplications, because the detailed path/route constraints can be specified through a subset of current (technology specific) CEP attributes. Ideally we should split the CEP object between intent and state attributes. Nigel Davis we also need to consider intents expressed as ranges., e.g. route the connection using a choice between three time-slots. Ramon Casellas in GMPLS works we started some study considering ranges, but we concluded that it was too complex with respect to actual requirements, where ranges are not required but only exact single time-slot / wavelength. Karthik Sethuraman outlines a Use Case where Orchestrator provisions an end-to-end connectivity spanning three distinct managed domains:
    1. First domain, the Orchestrator requests all the available wavelengths between UNI1 and ENNI1.
    2. Second domain, the Orchestrator requests the subset of available wavelengths between ENNI1 and ENNI2 among the ones available in the first domain.
    3. Third domain, the Orchestrator requests the subset of available wavelengths between ENNI2 and UNI2 among the ones available in the second domain.
  • Ramon Casellas suggests a simpler scenario, where Orchestrator asks to each domain all the available wavelengths and then enforces the one common to all three domains.
  • Nigel Davis we also need to consider multi-layer constraints, where not-yet-existing-client NEPs could be part of the constraints.
  • Ramon Casellas notes that PathComputationService already foresees 1-to-many Paths, hence using the diversityPolicy attribute of RoutingConstraint object it seems possible to implement some grouping provisioning.

Preliminary list of Path Computation Use Cases emerged during the discussion:

  1. Client requests Server to calculate more Paths between same end points, each Path with different constraints (e.g. focus on delay or focus on cost, etc.). One of these Paths will be used as routing constraint for ConnectivityService provisioning. Note that a variable degree of routing diversity could be required between the group of Paths. To be considered also the multiplicity between PathComputationService and its Paths.
  2. ERO provisioning, Client requests more detailed constraints, e.g. the exact label / time-slot / wavelength of a Path. Single layer only.
  3. Stateless PCE, the calculated Path is not created at Server side, i.e. is seen at the management interface only in the reply of Path provisioning Post/RPC (Post could inherently not support a stateless provisioning).
  4. Provisioning of a group of ConnectivityServices, with specific rules for the group (e.g. degree of diversity).


Path Computation / Planning / Check Service Feasibility (providing an Explicit Route Object)

Fully Explicit Route indication



Nigel Davis presents otcc2020.ND.010_TAPI-ConnectivityServiceComputationService.pptx

  • There is an error in the current UML definition, the correct association between Path and Link is [* → 1..*] (rather than 1→ 1..*) because more Paths can share same Link.
  • Consider the static and dynamic cost of a Link, more in general it is required a dynamic planning (or on-line planning), where planned paths can change during their lifecycle to follow network changes (evolution, faults) while respecting the originally specified constraints (but there is only one RoutingConstraint instance per PathComputationService instance).
  • Karthik Sethuraman recalls that Path Computation was introduced for architectural purposes, and stateful. Nigel Davis presents the PathSet concept:

  • Predefined PathSets:
    • Set provides alternative Link Chains
    • Different PathSets may be used for different services
    • PathSets may be constructed for future cases that require different routing to current
    • PathSets are not provisioned
  • Agreed that PathSet is a generalization of the grouping solution proposed by Ramon Casellas in previous slot P1.2
  • Nigel Davisnoted that there is a distinction between a path and a connection in a connection oriented context where the connection has explicit network edge points but a path only sets out intermediate links. 
  • It was noted that a PathComputationService is defined in terms of PathServiceEndPoints which are SIPs and hence is edge to edge. Editor's note (ND): So a Path that is chosen as a constraint in a ConnectivityService request should belong to a PathComputationService that has the same SIPs as the requested ConnectivityService (as other Paths, even those that go between the right NEs may not be viable for the SIPs - of course a path may not have capacity anyway as it was precomputed intentionally with no analysis of capacity) 
  • Nigel Davis we should explore whether to collapse Path Computation into ConnectivityService provisioning, given that the Path is essentially a pre-computed intent for the Route.
    • Also consider the provisioning of multiple ConnectivityServices with intra-constraints.
    • The stateful paths may be known by a Control Plane and used for preplanned restoration etc.
    • Editor's note (ND): The distinction between a stateful Path and a ConnectivityService is that the Path is not activated to carry traffic and cannot be activated to carry traffic until used by a ConnectivityService and the connections are provisioned and activated. 
    • Editor's note (ND): There are several dimensions here which need to be considered in any convergence/collapse, 
      • statefulness
        • stateful: Path/ConnectivityService are retained by the provider systems (controller and potentially a control plane or the underlying devices)
        • stateless: The path/ConnectivityService is not retained by the provider systems
      • specificity (there may be other forms of specificity in addition to the two listed... it could be argued that elements of viability are actually also elements of specificity)
        • path: Just a description of a way to get across the network for some purposes without details of the channel etc.
        • connection: A specific way across the network with details of the channels etc. sufficient to carry traffic assuming viable
      • viability
        • viable: proven to have available potential capacity etc. at the point of calculation. It is questionable whether a path can be considered as viable. 
      • reservation:
        • reserved (must be stateful, ought to be viable, ought to be complete, i.e., a full connection statement): all necessary resources have been allocated and are not available to others (in a timeframe etc.)
      • deployment:
        • deployed (essentially is reserved and stateful, ought to be viable, ought to be complete): all necessary resources are in place in the network and are setup for the purpose of supporting the ConnectivityService
      • operation:
        • operating (essentially is reserved, stateful, viable, complete): resources are operating and providing the necessary ConnectivityService
    • Editor's note (ND): There is a corner case of a serial compound link that appears as a link but is supported by serial connections within the span of the link where those connections are of the same layer/qualifier as the connection and where that necessary capacity can be reserved etc. 
  • Andrea Mazzini considers that the Path could also be infrastructure, i.e. a virtual network to be used for future end-to-end ConnectivityService provisioning.
    • E.g. the ODUk Serial Compound Link Connection which interconnects the transponders.
    • Editor's note (ND): A virtual network is more than just paths. We need to study this in detail, I think it will end up being Node/Link construction with some viability considerations etc. as per discussion in the core. The current TAPI VN is lacking.


Consolidation of ODU OAM


Nigel Davis indicates that the CurrentData is not associated to the MEP/MIP/CEP instance providing the measurement.

  • Note that in Ethernet OAM the association is likely inherently defined by OAM job types.
  • Agreed that CurrentData shall include a reference to the MEP/MIP/CEP instance providing the measurement.

Discussion on PM data collection, there could be a degree of variations between the two extreme cases where PM data storage is either exclusively maintained on Server or on Client Controller side. These architectural differences can require different PM data structures.

  • Nigel Davis there is the need to represent policies like zero suppression and repetition suppression, by e.g. a new dedicated object, distinct but maybe related to OamProfile object.

Agreed that FEC parameters shall augment CurrentData and HistoryData rather than OTU CEP.

  • The FEC related measurements can be triggered automatically when OTU MEP (pac of OTU CEP) is provisioned.

The ODUCn contains n instances of the ODU PM overhead, numbered 1 to n (PM #1 to PM #n).

  • Agreed to model this multiplicity by a 1..n packages of ODU MEP, and analogously by an array of measurements for CurrentData/HistoryData.
  • Andrea Mazzini list the OTN related questions still open.
  • Nigel Davis explore various pm information density improvement policies such as zero suppression.

Tue 13P1
Physical Route and Optical impairments

Nigel Davis do we have specific requirements on Physical Topology model?

  • Ramon Casellas UC for the validation of a path provided by an external tool like GNPy
  • Andrea Mazzini UC for the physical diverse route in an equipment
  • Andrea Mazzini note that draft-ietf-ccamp-optical-impairment-topology-yang models the internal ROADM topology by path categories of the Media Channels inside the ROADM:
    • Express path: MC path between two line ports of the ROADM

    • Add Path: MC path from an Add port to a line port of the ROADM

    • Drop path: MC path from a line port to a Drop port of the ROADM

  • Ramon Casellas to get the clear picture of the optical impairments it is necessary a detailed logical view.
  • Karthik Sethuraman underlines that there is also a communication issue, TAPI abstract concepts could be difficult to be understood by WDM folks, they use a different terminology.
  • Ramon Casellas GNPy Json modules are manually built and in general the focus is on amplifiers, e.g. 96 vector values for the advanced amplifier model.
    • Note that it is assumed full load for the simulations, no partial load simulations so far.
    • Note that many parameters are not fully described.
    • Maybe is not necessary to represent 96 TAPI Connections for the amplifier model.
      • Nigel Davis in fact the amplifier has typically one single Connection between its ports.

Karthik Sethuraman shows

  • In we can find the managed objects:
    • Node, with types: ROADM, Amplifier, Transceiver, Fiber
    • Link: pure association between Nodes, note that the "Fiber" is a Node type.
  • It seems there are no "Ports" of e.g. a ROADM Node, looking at CORONET_Global_Topology.xls example
  • In excel.rst some more descriptions:
                <--           east cable from a to z                                   --> 
NodeA ; NodeZ ; Distance km ; Fiber type ; Lineic att ; Con_in ; Con_out ; PMD ; Cable Id ;
<-- west from z to a -->
Distance km ; Fiber type ; Lineic att ; Con_in ; Con_out ; PMD ; Cable Id
  • GNPy documentation refers to draft-ietf-teas-yang-path-computation (YANG Data Model for requesting Path Computation).
  • Karthik Sethuraman the question is how to retrieve the amplifier properties through TAPI?
  • After some discussion, a possible approach could be a recursive topology, where the higher partitioning level shows the Connections spanning the Node (e.g. ROADM Node) and the lower partitioning level shows an abstraction of the internal topology of the ROADM, with "cross connection" view only where useful for management.


Physical Route and Optical impairments




European H2020 PASSION Project

Politecnico di Milano and SM-Optics

2.3 ?
Thu 15P1

Consolidation of Alarm/TCA


Andrea Mazzini- Discussion on "stateful" alarm/TCA


OTS and OMS model

2.1.3 ?



UNI Client interfaces modelling. DSR/ODU multiplexing over ODU

2.3 ?

Ramon Casellas for UNI DSR over ODU mux

Call Coordinates:

Topic: OTCC TAPI Multiday Meeting
Time: Apr 12, 2021 04:00 AM Pacific Time (US and Canada)
        Every day, until Apr 15, 2021, 3 occurrence(s)
        Apr 12, 2021 04:00 AM
        Apr 13, 2021 04:00 AM
        Apr 15, 2021 04:00 AM
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