Flow and Service Information Model for Deterministic Networking (DetNet)
RFC 9016

Document Type RFC - Informational (March 2021; No errata)
Authors Balazs Varga  , János Farkas  , Rodney Cummings  , Yuanlong Jiang  , Don Fedyk 
Last updated 2021-03-30
Replaces draft-farkas-detnet-flow-information-model
Stream Internet Engineering Task Force (IETF)
Formats plain text html xml pdf htmlized bibtex
Reviews
Stream WG state Submitted to IESG for Publication
Document shepherd Lou Berger
Shepherd write-up Show (last changed 2020-04-30)
IESG IESG state RFC 9016 (Informational)
Action Holders
(None)
Consensus Boilerplate Yes
Telechat date
Responsible AD Deborah Brungard
Send notices to Lou Berger <lberger@labn.net>
IANA IANA review state IANA OK - No Actions Needed
IANA action state No IANA Actions


Internet Engineering Task Force (IETF)                          B. Varga
Request for Comments: 9016                                     J. Farkas
Category: Informational                                         Ericsson
ISSN: 2070-1721                                              R. Cummings
                                                    National Instruments
                                                                Y. Jiang
                                                                  Huawei
                                                                D. Fedyk
                                                         LabN Consulting
                                                              March 2021

Flow and Service Information Model for Deterministic Networking (DetNet)

Abstract

   This document describes the flow and service information model for
   Deterministic Networking (DetNet).  These models are defined for IP
   and MPLS DetNet data planes.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are candidates for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc9016.

Copyright Notice

   Copyright (c) 2021 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
     1.1.  Goals
     1.2.  Non-Goals
   2.  Terminology
     2.1.  Terms Used in This Document
     2.2.  Abbreviations
     2.3.  Naming Conventions
   3.  DetNet Domain and Its Modeling
     3.1.  DetNet Service Overview
     3.2.  Reference Points Used in Modeling
     3.3.  Information Elements
   4.  App-Flow-Related Parameters
     4.1.  App-Flow Characteristics
     4.2.  App-Flow Requirements
   5.  DetNet Flow-Related Parameters
     5.1.  Management ID of the DetNet Flow
     5.2.  Payload Type of the DetNet Flow
     5.3.  Format of the DetNet Flow
     5.4.  Identification and Specification of DetNet Flows
       5.4.1.  DetNet MPLS Flow Identification and Specification
       5.4.2.  DetNet IP Flow Identification and Specification
     5.5.  Traffic Specification of the DetNet Flow
     5.6.  Endpoints of the DetNet Flow
     5.7.  Rank of the DetNet Flow
     5.8.  Status of the DetNet Flow
     5.9.  Requirements of the DetNet Flow
       5.9.1.  Minimum Bandwidth of the DetNet Flow
       5.9.2.  Maximum Latency of the DetNet Flow
       5.9.3.  Maximum Latency Variation of the DetNet Flow
       5.9.4.  Maximum Loss of the DetNet Flow
       5.9.5.  Maximum Consecutive Loss of the DetNet Flow
       5.9.6.  Maximum Misordering Tolerance of the DetNet Flow
     5.10. BiDir Requirement of the DetNet Flow
   6.  DetNet Service-Related Parameters
     6.1.  Management ID of the DetNet Service
     6.2.  Delivery Type of the DetNet Service
     6.3.  Delivery Profile of the DetNet Service
       6.3.1.  Minimum Bandwidth of the DetNet Service
       6.3.2.  Maximum Latency of the DetNet Service
       6.3.3.  Maximum Latency Variation of the DetNet Service
       6.3.4.  Maximum Loss of the DetNet Service
       6.3.5.  Maximum Consecutive Loss of the DetNet Service
       6.3.6.  Maximum Misordering Tolerance of the DetNet Service
     6.4.  Connectivity Type of the DetNet Service
     6.5.  BiDir Requirement of the DetNet Service
     6.6.  Rank of the DetNet Service
     6.7.  Status of the DetNet Service
   7.  Flow-Specific Operations
     7.1.  Join Operation
     7.2.  Leave Operation
     7.3.  Modify Operation
   8.  Summary
   9.  IANA Considerations
   10. Security Considerations
   11. References
     11.1.  Normative References
     11.2.  Informative References
   Authors' Addresses

1.  Introduction

   Deterministic Networking (DetNet) provides a capability to carry
   specified unicast or multicast data flows for real-time applications
   with extremely low packet loss rates and assured maximum end-to-end
   delivery latency.  A description of the general background and
   concepts of DetNet can be found in [RFC8655].

   This document describes the DetNet flow and service information
   model.  For reference, [RFC3444] describes the rationale behind
   information models in general.  This document describes the flow and
   service information models for operators and users to understand
   DetNet services and for implementors as a guide to the functionality
   required by DetNet services.

   The DetNet architecture treats the DetNet-related data plane
   functions decomposed into two sub-layers: a service sub-layer and a
   forwarding sub-layer.  The service sub-layer is used to provide
   DetNet service protection and reordering.  The forwarding sub-layer
   provides resource allocation (to ensure low loss, assured latency,
   and limited out-of-order delivery) and leverages traffic engineering
   mechanisms.

   DetNet service utilizes IP or MPLS, and DetNet is currently defined
   for IP and MPLS networks, as shown in Figure 1, which is a reprint of
   Figure 2 from [RFC8938].  IEEE 802.1 Time-Sensitive Networking (TSN)
   utilizes Ethernet and is defined over Ethernet networks.  A DetNet
   flow includes one or more application-level flow (App-flow) as
   payload.  App-flows can be Ethernet, MPLS, or IP flows, which impacts
   which header fields are utilized to identify a flow.  DetNet flows
   are identified by the DetNet encapsulation of App-flow(s) (e.g., MPLS
   labels, IP 6-tuples, etc.).  In some scenarios, App-flow and DetNet
   flow look similar on the wire (e.g., Layer 3 (L3) App-flow over a
   DetNet IP network).

                                             +-----+
                                             | TSN |
                        +-------+          +-+-----+-+
                        | DN IP |          | DN MPLS |
                     +--+--+----+----+   +-+---+-----+-+
                     | TSN | DN MPLS |   | TSN | DN IP |
                     +-----+---------+   +-----+-------+

       Figure 1: DetNet Service Examples as per Data Plane Framework

   As shown in Figure 1 and as described in [RFC8938], a DetNet flow can
   be treated as an App-flow, e.g., at DetNet flow aggregation or in a
   sub-network that interconnects DetNet nodes.

   The DetNet flow and service information model provided by this
   document contains both DetNet-flow- and App-flow-specific information
   in an integrated fashion.

   In a given network scenario, three information models can be
   distinguished:

   *  Flow information models that describe characteristics of data
      flows.  These models describe, in detail, all relevant aspects of
      a flow that are needed to support the flow properly by the network
      between the source and the destination(s).

   *  Service information models that describe characteristics of
      services being provided for data flows over a network.  These
      models can be treated as an information model that is network
      operator independent.

   *  Configuration information models that describe, in detail, the
      settings required on network nodes to provide proper service to a
      data flow.

   Service and flow information models are used between the user and the
   network operator.  Configuration information models are used between
   the management/control plane entity of the network and the network
   nodes.  They are shown in Figure 2.

              User                  Network Operator
                      flow/service
               /\      info model    +---+
              /  \ <---------------> | X |    management/control
              ----                   +-+-+       plane entity
                                       ^
                                       |   configuration
                                       |     info model
                                +------------+
                                v      |     |
                               +-+     |     v  network
                               +-+     v    +-+  nodes
                                      +-+   +-+
                                      +-+

         Figure 2: Usage of Information Models (Flow, Service, and
                               Configuration)

   The DetNet flow and service information model is based on [RFC8655]
   and the concept of the data model specified by [IEEE8021Qcc].  In
   addition to the TSN data model, [IEEE8021Qcc] also specifies
   configuration of TSN features (e.g., traffic scheduling specified by
   [IEEE8021Qbv]).  The common architecture and flow information model
   allow configured features to be consistent in certain deployment
   scenarios, e.g., when the network that provides the DetNet service
   includes both L3 and L2 network segments.

1.1.  Goals

   As expressed in the DetNet WG Charter [IETFDetNet], the DetNet WG
   collaborates with IEEE 802.1 TSN in order to define a common
   architecture for both Layers 2 and 3.  This is beneficial for several
   reasons, e.g., in order to simplify implementations and maintain
   consistency across diverse networks.  The flow and service
   information models are also aligned for those reasons.  Therefore,
   the DetNet flow and service information models described in this
   document are based on [IEEE8021Qcc], which is an amendment to
   [IEEE8021Q].

   This document specifies flow and service information models only.

1.2.  Non-Goals

   This document does not specify flow data models or DetNet
   configuration.  Therefore, the goals of this document differ from the
   goals of [IEEE8021Qcc], which also specifies the TSN data model and
   configuration of certain TSN features.

   The DetNet-specific YANG data model is described in [DETNET-YANG].

2.  Terminology

2.1.  Terms Used in This Document

   This document uses the terminology established in the DetNet
   architecture [RFC8655] and the DetNet data plane framework [RFC8938].
   The reader is assumed to be familiar with these documents and any
   terminology defined therein.  The DetNet <=> TSN dictionary of
   [RFC8655] is used to perform translation from [IEEE8021Qcc] to this
   document.

   The following terminology is used in accordance with [RFC8655]:

   App-flow      The payload (data) carried over a DetNet service.

   DetNet flow   A sequence of packets that conform uniquely to a flow
                 identifier and to which the DetNet service is to be
                 provided.  It includes any DetNet headers added to
                 support the DetNet service and forwarding sub-layers.

   The following terminology is introduced in this document:

   Source        Reference point for an App-flow, where the flow starts.

   Destination   Reference point for an App-flow, where the flow
                 terminates.

   DN Ingress    Reference point for the start of a DetNet flow.
                 Networking technology-specific encapsulation may be
                 added here to the served App-flow(s).

   DN Egress     Reference point for the end of a DetNet flow.
                 Networking technology-specific encapsulation may be
                 removed here from the served App-flow(s).

2.2.  Abbreviations

   The following abbreviations are used in this document:

   DetNet        Deterministic Networking

   DN            DetNet

   MPLS          Multiprotocol Label Switching

   PSN           Packet Switched Network

   TSN           Time-Sensitive Networking

2.3.  Naming Conventions

   The following naming conventions were used for naming information
   model components in this document.  It is recommended that extensions
   of the model use the same conventions.

   *  Descriptive names are used.

   *  Names start with uppercase letters.

   *  Composed names use capital letters for the first letter of each
      component.  All other letters are lowercase, even for
      abbreviations.  Exceptions are made for abbreviations containing a
      mixture of lowercase and capital letters, such as IPv6.  Example
      composed names are SourceMacAddress and DestinationIPv6Address.

3.  DetNet Domain and Its Modeling

3.1.  DetNet Service Overview

   The DetNet service can be defined as a service that provides a
   capability to carry a unicast or a multicast data flow for an
   application with constrained requirements on network performance,
   e.g., low packet loss rate and/or latency.

   Figures 5 and 8 in [RFC8655] show the DetNet service-related
   reference points and main components.

3.2.  Reference Points Used in Modeling

   From a service-design perspective, a fundamental question is the
   location of the service/flow endpoints, i.e., where the service/flow
   starts and ends.

   App-flow-specific reference points are the source (where it starts)
   and the destination (where it terminates).  Similarly, a DetNet flow
   has reference points termed "DN Ingress" (where a DetNet flow starts)
   and "DN Egress" (where a DetNet flow ends).  These reference points
   may coexist in the same node (e.g., in a DetNet IP end system).  DN
   Ingress and DN Egress reference points are intermediate reference
   points for a served App-flow.

   In this document, all reference points are assumed to be packet-based
   reference points.  A DN Ingress may add and a DN Egress may remove
   networking technology-specific encapsulation to/from the served App-
   flow(s) (e.g., MPLS label(s), UDP, and IP headers).

3.3.  Information Elements

   The DetNet flow information model and the service information model
   rely on three groups of information elements:

   App-flow-related parameters:  These describe the App-flow
      characteristics (e.g., identification, encapsulation, traffic
      specification, endpoints, status, etc.) and the App-flow service
      expectations (e.g., delay, loss, etc.).

   DetNet flow-related parameters:  These describe the DetNet flow
      characteristics (e.g., identification, format, traffic
      specification, endpoints, rank, etc.).

   DetNet service-related parameters:  These describe the expected
      service characteristics (e.g., delivery type, connectivity delay/
      loss, status, rank, etc.).

   In the information model, a DetNet flow contains one or more
   (aggregated) App-flows (N:1 mapping).  During DetNet aggregation, the
   aggregated DetNet flows are treated simply as App-flows and the
   aggregate is the DetNet flow, which provides N:1 mapping.  Similarly,
   there is an aggregated many-to-one relationship for the DetNet
   flow(s) to the DetNet service.

4.  App-Flow-Related Parameters

   When DetNet service is required by time-/loss-sensitive
   application(s) running on an end system during communication with its
   peer(s), the resulting data exchange has various requirements on
   delay and/or loss parameters.

4.1.  App-Flow Characteristics

   App-flow characteristics are described by the following parameters:

   FlowID:       a unique (management) identifier of the App-flow, which
                 can be used to define the N:1 mapping of App-flows to a
                 DetNet flow

   FlowType:     set by the encapsulation format of the flow, which can
                 be Ethernet (TSN), MPLS, or IP

   DataFlowSpecification:  a flow descriptor, defining which packets
                 belongs to a flow, using specific packet header fields,
                 such as src-addr, dst-addr, label, VLAN-ID, etc.

   TrafficSpecification:  a flow descriptor, defining traffic
                 parameters, such as packet size, transmission time
                 interval, and maximum packets per time interval

   FlowEndpoints:  delineates the start and end reference points of the
                 App-flow by pointing to the source interface/node and
                 destination interface(s)/node(s)

   FlowStatus:   indicates the status of the App-flow with respect to
                 the establishment of the flow by the connected network,
                 e.g., ready, failed, etc.

   FlowRank:     indicates the rank of this flow relative to other flows
                 in the connected network

      |  Note: When defining the N:1 mapping of App-flows to a DetNet
      |  flow, the App-flows must have the same FlowType and different
      |  DataFlowSpecification parameters.

4.2.  App-Flow Requirements

   App-flow requirements are described by the following parameters:

   FlowRequirements:  defines the attributes of the App-flow regarding
                 bandwidth, latency, latency variation, loss, and
                 misordering tolerance

   FlowBiDir:    defines the data path requirement of the App-flow
                 whether it must share the same data path and physical
                 path for both directions through the network, e.g., to
                 provide congruent paths in the two directions

5.  DetNet Flow-Related Parameters

   The data model specified by [IEEE8021Qcc] describes data flows using
   TSN service as periodic flows with fixed packet size (i.e., Constant
   Bitrate (CBR) flows) or with variable packet size.  The same concept
   is applied for flows using DetNet service.

   Latency and loss parameters are correlated because the effect of late
   delivery can result in data loss for an application.  However, not
   all applications require hard limits on both latency and loss.  For
   example, some real-time applications allow graceful degradation if
   loss happens (e.g., sample-based data processing and media
   distribution).  Some other applications may require high-bandwidth
   connections that make use of packet replication techniques that are
   economically challenging or even impossible.  Some applications may
   not tolerate loss but are not delay sensitive (e.g., bufferless
   sensors).  Time- or loss-sensitive applications may have somewhat
   special requirements, especially for loss (e.g., no loss over two
   consecutive communication cycles, very low outage time, etc.).

   DetNet flows have the following attributes:

   a.  DnFlowID (Section 5.1)
   b.  DnPayloadType (Section 5.2)
   c.  DnFlowFormat (Section 5.3)
   d.  DnFlowSpecification (Section 5.4)
   e.  DnTrafficSpecification (Section 5.5)
   f.  DnFlowEndpoints (Section 5.6)
   g.  DnFlowRank (Section 5.7)
   h.  DnFlowStatus (Section 5.8)

   DetNet flows have the following requirement attributes:

   a.  DnFlowRequirements (Section 5.9)
   b.  DnFlowBiDir (Section 5.10)

   Flow attributes are described in the following sections.

5.1.  Management ID of the DetNet Flow

   A unique (management) identifier is needed for each DetNet flow
   within the DetNet domain.  It is specified by DnFlowID.  It can be
   used to define the N:1 mapping of DetNet flows to a DetNet service.

5.2.  Payload Type of the DetNet Flow

   The DnPayloadType attribute is set according to the encapsulated App-
   flow format.  The attribute can be Ethernet, MPLS, or IP.

5.3.  Format of the DetNet Flow

   The DnFlowFormat attribute is set according to the DetNet PSN
   technology.  The attribute can be MPLS or IP.

5.4.  Identification and Specification of DetNet Flows

   Identification options for DetNet flows at the Ingress/Egress and
   within the DetNet domain are specified as follows; see Section 5.4.1
   for DetNet MPLS flows and Section 5.4.2 for DetNet IP flows.

5.4.1.  DetNet MPLS Flow Identification and Specification

   The identification of DetNet MPLS flows within the DetNet domain is
   based on the MPLS context in the service information model.  The
   attributes are specific to the MPLS forwarding paradigm within the
   DetNet domain [RFC8964].  DetNet MPLS flows can be identified and
   specified by the following attributes:

   a.  SLabel
   b.  FLabelStack

5.4.2.  DetNet IP Flow Identification and Specification

   DetNet IP flows can be identified and specified by the following
   attributes [RFC8939]:

   a.  SourceIpAddress
   b.  DestinationIpAddress
   c.  IPv6FlowLabel
   d.  Dscp
   e.  Protocol
   f.  SourcePort
   g.  DestinationPort
   h.  IPSecSpi

   The IP 6-tuple that is used for DetNet IP flow identification
   consists of items a, b, d, e, f, and g.  Items c and h are additional
   attributes that can be used for DetNet flow identification in
   addition to the 6-tuple.  The 6-tuple and use of wild cards for these
   attributes are specified in [RFC8939].

5.5.  Traffic Specification of the DetNet Flow

   The DnTrafficSpecification attributes specify how the DN Ingress
   transmits packets for the DetNet flow.  This is effectively the
   promise/request of the DN Ingress to the network.  The network uses
   this traffic specification to allocate resources and adjust queue
   parameters in network nodes.

   TrafficSpecification has the following attributes:

   a.  Interval: the period of time in which the traffic specification
       is specified

   b.  MaxPacketsPerInterval: the maximum number of packets that the
       Ingress will transmit in one Interval

   c.  MaxPayloadSize: the maximum payload size that the Ingress will
       transmit

   d.  MinPayloadSize: the minimum payload size that the Ingress will
       transmit

   e.  MinPacketsPerInterval: the minimum number of packets that the
       Ingress will transmit in one Interval

   These attributes can be used to describe any type of traffic (e.g.,
   CBR, Variable Bitrate (VBR), etc.) and can be used during resource
   allocation to represent worst-case scenarios.  Intervals are
   specified as an integer number of nanoseconds.  PayloadSizes are
   specified in octets.

   Flows exceeding the traffic specification (i.e., having more traffic
   than defined by the maximum attributes) may receive a different
   network behavior than the DetNet network has been engineered for.
   Excess traffic due to malicious or malfunctioning devices can be
   prevented or mitigated (e.g., through the use of existing mechanisms,
   such as policing and shaping).

   When MinPayloadSize and MinPacketsPerInterval parameters are used,
   all packets less than the MinPayloadSize will be counted as being of
   the size MinPayloadSize during packet processing when packet size
   matters, e.g., when policing; all flows having less than
   MinPacketsPerInterval will be counted as having MinPacketsPerInterval
   when the number of packets per interval matters, e.g., during
   resource reservation.  However, flows having less than
   MinPacketsPerInterval may result in a different network behavior than
   the DetNet network has been engineered for.  MinPayloadSize and
   MinPacketsPerInterval parameters, for example, may be used when
   engineering the latency bounds of a DetNet flow when Packet Ordering
   Function (POF) is applied to the given DetNet flow.

   Further optional attributes can be considered to achieve more
   efficient resource allocation.  Such optional attributes might be
   worth for flows with soft requirements (i.e., the flow is only loss
   sensitive or only delay sensitive but not both delay and loss
   sensitive).  Possible options about how to extend
   DnTrafficSpecification attributes is for further discussion.

5.6.  Endpoints of the DetNet Flow

   The DnFlowEndpoints attribute defines the start and end reference
   points of the DetNet flow by pointing to the ingress interface/node
   and egress interface(s)/node(s).  Depending on the network scenario,
   it defines an interface or a node.  Interface can be defined, for
   example, if the App-flow is a TSN Stream, and it is received over a
   well-defined User-to-Network Interface (UNI).  For example, for App-
   flows with MPLS encapsulation, defining an ingress node is more
   common when a per-platform label space is used.

5.7.  Rank of the DetNet Flow

   The DnFlowRank attribute provides the rank of this flow relative to
   other flows in the DetNet domain.  Rank (range: 0-255) is used by the
   DetNet domain to decide which flows can and cannot exist when network
   resources reach their limit.  Rank is used to help to determine which
   flows can be bumped (i.e., removed from node configuration thereby
   releasing its resources) if, for example, a port of a node becomes
   oversubscribed (e.g., due to network reconfiguration).  DnFlowRank
   value 0 is the highest priority.

5.8.  Status of the DetNet Flow

   The DnFlowStatus attribute provides the status of the DetNet flow
   with respect to the establishment of the flow by the DetNet domain.

   DnFlowStatus includes the following attributes:

   a.  DnIngressStatus is an enumeration for the status of the flow's
       Ingress reference point:

       None:  No Ingress.
       Ready:  Ingress is ready.
       Failed:  Ingress failed.
       OutOfService:  Administratively blocked.

   b.  DnEgressStatus is an enumeration for the status of the flow's
       Egress reference points:

       None:  No Egress.
       Ready:  All Egresses are ready.
       PartialFailed:  One or more Egress is ready, and one or more
          Egress failed.  The DetNet flow can be used if the Ingress is
          Ready.
       Failed:  All Egresses failed.
       OutOfService:  All Egresses are administratively blocked.

   c.  FailureCode is a nonzero code that specifies the error if the
       DetNet flow encounters a failure (e.g., packet replication and
       elimination is requested but not possible or DnIngressStatus is
       Failed, DnEgressStatus is Failed, or DnEgressStatus is
       PartialFailed).

   Defining FailureCodes for DetNet is out of scope for this document.
   Table 46-1 of [IEEE8021Qcc] describes TSN failure codes.

5.9.  Requirements of the DetNet Flow

   The DnFlowRequirements attribute specifies requirements to ensure the
   service level desired for the DetNet flow.

   DnFlowRequirements includes the following attributes:

   a.  MinBandwidth (Section 5.9.1)
   b.  MaxLatency (Section 5.9.2)
   c.  MaxLatencyVariation (Section 5.9.3)
   d.  MaxLoss (Section 5.9.4)
   e.  MaxConsecutiveLossTolerance (Section 5.9.5)
   f.  MaxMisordering (Section 5.9.6)

5.9.1.  Minimum Bandwidth of the DetNet Flow

   MinBandwidth is the minimum bandwidth that has to be guaranteed for
   the DetNet flow.  MinBandwidth is specified in octets per second.

5.9.2.  Maximum Latency of the DetNet Flow

   MaxLatency is the maximum latency from Ingress to Egress(es) for a
   single packet of the DetNet flow.  MaxLatency is specified as an
   integer number of nanoseconds.

5.9.3.  Maximum Latency Variation of the DetNet Flow

   MaxLatencyVariation is the difference between the minimum and the
   maximum end-to-end, one-way latency.  MaxLatencyVariation is
   specified as an integer number of nanoseconds.

5.9.4.  Maximum Loss of the DetNet Flow

   MaxLoss defines the maximum Packet Loss Rate (PLR) requirement for
   the DetNet flow between the Ingress and Egress(es) and the loss
   measurement interval.

5.9.5.  Maximum Consecutive Loss of the DetNet Flow

   Some applications have special loss requirements, such as
   MaxConsecutiveLossTolerance.  The maximum consecutive loss tolerance
   parameter describes the maximum number of consecutive packets whose
   loss can be tolerated.  The maximum consecutive loss tolerance can be
   measured, for example, based on sequence number.

5.9.6.  Maximum Misordering Tolerance of the DetNet Flow

   MaxMisordering describes the tolerable maximum number of packets that
   can be received out of order.  The value zero for the maximum allowed
   misordering indicates that in-order delivery is required; misordering
   cannot be tolerated.

   The maximum allowed misordering can be measured, for example, based
   on sequence numbers.  When a packet arrives at the egress after a
   packet with a higher sequence number, the difference between the
   sequence number values cannot be bigger than "MaxMisordering + 1".

5.10.  BiDir Requirement of the DetNet Flow

   The DnFlowBiDir attribute defines the requirement that the flow and
   the corresponding reverse direction flow must share the same path
   (links and nodes) through the routed or switch network in the DetNet
   domain, e.g., to provide congruent paths in the two directions that
   share fate and path characteristics.

6.  DetNet Service-Related Parameters

   The DetNet service has the following attributes:

   a.  DnServiceID (Section 6.1)
   b.  DnServiceDeliveryType (Section 6.2)
   c.  DnServiceDeliveryProfile (Section 6.3)
   d.  DNServiceConnectivity (Section 6.4)
   e.  DnServiceBiDir (Section 6.5)
   f.  DnServiceRank (Section 6.6)
   g.  DnServiceStatus (Section 6.7)

   Service attributes are described in the following sections.

6.1.  Management ID of the DetNet Service

   The DnServiceId attribute is a unique (management) identifier for
   each DetNet service within the DetNet domain.  It can be used to
   define the many-to-one mapping of DetNet flows to a DetNet service.

6.2.  Delivery Type of the DetNet Service

   The DnServiceDeliveryType attribute is set according to the payload
   of the served DetNet flow (i.e., the encapsulated App-flow format).
   The attribute can be Ethernet, MPLS, or IP.

6.3.  Delivery Profile of the DetNet Service

   The DnServiceDeliveryProfile attribute specifies the delivery profile
   to ensure proper serving of the DetNet flow.

   DnServiceDeliveryProfile includes the following attributes:

   a.  MinBandwidth (Section 6.3.1)
   b.  MaxLatency (Section 6.3.2)
   c.  MaxLatencyVariation (Section 6.3.3)
   d.  MaxLoss (Section 6.3.4)
   e.  MaxConsecutiveLossTolerance (Section 6.3.5)
   f.  MaxMisordering (Section 6.3.6)

6.3.1.  Minimum Bandwidth of the DetNet Service

   MinBandwidth is the minimum bandwidth that has to be guaranteed for
   the DetNet service.  MinBandwidth is specified in octets per second
   and excludes additional DetNet header (if any).

6.3.2.  Maximum Latency of the DetNet Service

   MaxLatency is the maximum latency from Ingress to Egress(es) for a
   single packet of the DetNet flow.  MaxLatency is specified as an
   integer number of nanoseconds.

6.3.3.  Maximum Latency Variation of the DetNet Service

   MaxLatencyVariation is the difference between the minimum and the
   maximum end-to-end, one-way latency.  MaxLatencyVariation is
   specified as an integer number of nanoseconds.

6.3.4.  Maximum Loss of the DetNet Service

   MaxLoss defines the maximum Packet Loss Rate (PLR) parameter for the
   DetNet service between the Ingress and Egress(es) of the DetNet
   domain.

6.3.5.  Maximum Consecutive Loss of the DetNet Service

   Some applications have a special loss requirement, such as
   MaxConsecutiveLossTolerance.  The maximum consecutive loss tolerance
   parameter describes the maximum number of consecutive packets whose
   loss can be tolerated.  The maximum consecutive loss tolerance can be
   measured, for example, based on sequence number.

6.3.6.  Maximum Misordering Tolerance of the DetNet Service

   MaxMisordering describes the tolerable maximum number of packets that
   can be received out of order.  The maximum allowed misordering can be
   measured, for example, based on sequence number.  The value zero for
   the maximum allowed misordering indicates that in-order delivery is
   required; misordering cannot be tolerated.

6.4.  Connectivity Type of the DetNet Service

   Two connectivity types are distinguished: point-to-point (p2p) and
   point-to-multipoint (p2mp).  Connectivity type p2mp may be created by
   a forwarding function (e.g., p2mp LSP).  (Note that from a service
   perspective, mp2mp connectivity can be treated as a superposition of
   p2mp connections.)

6.5.  BiDir Requirement of the DetNet Service

   The DnServiceBiDir attribute defines the requirement that the flow
   and the corresponding reverse direction flow must share the same path
   (links and nodes) through the routed or switch network in the DetNet
   domain, e.g., to provide congruent paths in the two directions that
   share fate and path characteristics.

6.6.  Rank of the DetNet Service

   The DnServiceRank attribute provides the rank of a service instance
   relative to other services in the DetNet domain.  DnServiceRank
   (range: 0-255) is used by the network in case of network resource
   limitation scenarios.  DnServiceRank value 0 is the highest priority.

6.7.  Status of the DetNet Service

   The DnServiceStatus information group includes elements that specify
   the status of the service-specific state of the DetNet domain.  This
   information group informs the user whether or not the service is
   ready for use.

   DnServiceStatus includes the following attributes:

   a.  DnServiceIngressStatus is an enumeration for the status of the
       service's Ingress:

       None:  No Ingress.
       Ready:  Ingress is ready.
       Failed:  Ingress failed.
       OutOfService:  Administratively blocked.

   b.  DnServiceEgressStatus is an enumeration for the status of the
       service's Egress:

       None:  No Egress.
       Ready:  All Egresses are ready.
       PartialFailed:  One or more Egress is ready, and one or more
          Egress failed.  The DetNet flow can be used if the Ingress is
          Ready.
       Failed:  All Egresses failed.
       OutOfService:  Administratively blocked.

   c.  DnServiceFailureCode is a nonzero code that specifies the error
       if the DetNet service encounters a failure (e.g., packet
       replication and elimination is requested but not possible or
       DnServiceIngressStatus is Failed, DnServiceEgressStatus is
       Failed, or DnServiceEgressStatus is PartialFailed).

   Defining DnServiceFailureCodes for DetNet service is out of scope for
   this document.  Table 46-1 of [IEEE8021Qcc] describes TSN failure
   codes.

7.  Flow-Specific Operations

   The DetNet flow information model relies on three high-level
   information groups:

   DnIngress:  The DnIngress information group includes elements that
      specify the source for a single DetNet flow.  This information
      group is applied from the user of the DetNet service to the
      network.

   DnEgress:  The DnEgress information group includes elements that
      specify the destination for a single DetNet flow.  This
      information group is applied from the user of the DetNet service
      to the network.

   DnFlowStatus:  The DnFlowStatus information group includes elements
      that specify the status of the flow in the network.  This
      information group is applied from the network to the user of the
      DetNet service.  This information group informs the user whether
      or not the DetNet flow is ready for use.

   There are three possible operations for each DetNet flow with respect
   to its DetNet service at a DN Ingress or a DN Egress (similar to App-
   flows at a source or a destination):

   Join:  DN Ingress/DN Egress intends to join the flow.
   Leave:  DN Ingress/DN Egress intends to leave the flow.
   Modify:  DN Ingress/DN Egress intends to change the flow.

7.1.  Join Operation

   For the join operation, the DnFlowSpecification, DnFlowRank,
   DnFlowEndpoint, and DnTrafficSpecification are included within the
   DnIngress or DnEgress information groups.  For the join operation,
   the DnServiceRequirements groups can be included.

7.2.  Leave Operation

   For the leave operation, the DnFlowSpecification and DnFlowEndpoint
   are included within the DnIngress or DnEgress information groups.

7.3.  Modify Operation

   For the modify operation, the DnFlowSpecification, DnFlowRank,
   DnFlowEndpoint, and DnTrafficSpecification are included within the
   DnIngress or DnEgress information group.  For the join operation, the
   DnServiceRequirements groups can be included.

   The Modify operation can be considered to address cases when a flow
   is slightly changed, e.g., only MaxPayloadSize (Section 5.5) has been
   changed.  The advantage of having a Modify is that it allows
   initiation of a change of flow spec while leaving the current flow
   operating until the change is accepted.  If there is no linkage
   between the Join and the Leave, then while figuring out whether the
   new flow spec can be supported, the controller entity has to assume
   that the resources committed to the current flow are in use.  By
   using Modify, the controller entity knows that the resources
   supporting the current flow can be available for supporting the
   altered flow.  Modify is considered to be an optional operation due
   to possible controller plane limitations.

8.  Summary

   This document describes the DetNet flow information model and the
   service information model for DetNet IP networks and DetNet MPLS
   networks.  These models are used as input for creating the DetNet-
   specific YANG module.

9.  IANA Considerations

   This document has no IANA actions.

10.  Security Considerations

   The external interfaces of the DetNet domain need to be subject to
   appropriate confidentiality.  Additionally, knowledge of which flows/
   services are provided to a customer or delivered by a network
   operator may supply information that can be used in a variety of
   security attacks.  Security considerations for DetNet are described
   in detail in [DETNET-SECURITY].  General security considerations are
   described in [RFC8655].  This document discusses modeling the
   information, not how it is exchanged.

11.  References

11.1.  Normative References

   [IEEE8021Qcc]
              IEEE, "IEEE Standard for Local and Metropolitan Area
              Networks--Bridges and Bridged Networks -- Amendment 31:
              Stream Reservation Protocol (SRP) Enhancements and
              Performance Improvements",
              DOI 10.1109/IEEESTD.2018.8514112, IEEE 802.1Qcc-2018,
              October 2013,
              <https://ieeexplore.ieee.org/document/8514112/>.

   [RFC8655]  Finn, N., Thubert, P., Varga, B., and J. Farkas,
              "Deterministic Networking Architecture", RFC 8655,
              DOI 10.17487/RFC8655, October 2019,
              <https://www.rfc-editor.org/info/rfc8655>.

   [RFC8939]  Varga, B., Ed., Farkas, J., Berger, L., Fedyk, D., and S.
              Bryant, "Deterministic Networking (DetNet) Data Plane:
              IP", RFC 8939, DOI 10.17487/RFC8939, November 2020,
              <https://www.rfc-editor.org/info/rfc8939>.

   [RFC8964]  Varga, B., Ed., Farkas, J., Berger, L., Malis, A., Bryant,
              S., and J. Korhonen, "Deterministic Networking (DetNet)
              Data Plane: MPLS", RFC 8964, DOI 10.17487/RFC8964, January
              2021, <https://www.rfc-editor.org/info/rfc8964>.

11.2.  Informative References

   [DETNET-SECURITY]
              Grossman, E., Mizrahi, T., and A. J. Hacker,
              "Deterministic Networking (DetNet) Security
              Considerations", Work in Progress, Internet-Draft, draft-
              ietf-detnet-security-16, 2 March 2021,
              <https://tools.ietf.org/html/draft-ietf-detnet-security-
              16>.

   [DETNET-YANG]
              Geng, X., Chen, M., Ryoo, Y., Fedyk, D., Rahman, R., and
              Z. Li, "Deterministic Networking (DetNet) YANG Model",
              Work in Progress, Internet-Draft, draft-ietf-detnet-yang-
              11, 19 February 2021,
              <https://tools.ietf.org/html/draft-ietf-detnet-yang-11>.

   [IEEE8021Q]
              IEEE, "IEEE Standard for Local and Metropolitan Area
              Networks--Bridges and Bridged Networks",
              DOI 10.1109/IEEESTD.2018.8403927, IEEE 802.1Q-2018, July
              2018, <https://ieeexplore.ieee.org/document/8403927>.

   [IEEE8021Qbv]
              IEEE, "IEEE Standard for Local and metropolitan area
              networks -- Bridges and Bridged Networks - Amendment 25:
              Enhancements for Scheduled Traffic",
              DOI 10.1109/IEEESTD.2016.8613095, IEEE 802.1Qbv-2015,
              March 2016,
              <https://ieeexplore.ieee.org/document/8613095>.

   [IETFDetNet]
              IETF, "Deterministic Networking (detnet)",
              <https://datatracker.ietf.org/wg/detnet/charter/>.

   [RFC3444]  Pras, A. and J. Schoenwaelder, "On the Difference between
              Information Models and Data Models", RFC 3444,
              DOI 10.17487/RFC3444, January 2003,
              <https://www.rfc-editor.org/info/rfc3444>.

   [RFC8938]  Varga, B., Ed., Farkas, J., Berger, L., Malis, A., and S.
              Bryant, "Deterministic Networking (DetNet) Data Plane
              Framework", RFC 8938, DOI 10.17487/RFC8938, November 2020,
              <https://www.rfc-editor.org/info/rfc8938>.

Authors' Addresses

   Balázs Varga
   Ericsson
   Budapest
   Magyar Tudosok krt. 11.
   1117
   Hungary

   Email: balazs.a.varga@ericsson.com

   János Farkas
   Ericsson
   Budapest
   Magyar Tudosok krt. 11.
   1117
   Hungary

   Email: janos.farkas@ericsson.com

   Rodney Cummings
   National Instruments
   Bldg. C
   11500 N. Mopac Expwy
   Austin, TX 78759-3504
   United States of America

   Email: rodney.cummings@ni.com

   Yuanlong Jiang
   Huawei
   Bantian, Longgang district
   Shenzhen
   518129
   China

   Email: jiangyuanlong@huawei.com

   Don Fedyk
   LabN Consulting, L.L.C.

   Email: dfedyk@labn.net