DetNet Flow Information Model
draft-ietf-detnet-flow-information-model-04
The information below is for an old version of the document.
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| Authors | János Farkas , Balazs Varga , Rodney Cummings , Yuanlong Jiang | ||
| Last updated | 2019-07-08 (Latest revision 2019-03-08) | ||
| Replaces | draft-farkas-detnet-flow-information-model | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-detnet-flow-information-model-04
DetNet J. Farkas
Internet-Draft B. Varga
Intended status: Standards Track Ericsson
Expires: January 9, 2020 R. Cummings
National Instruments
Y. Jiang
Huawei Technologies Co., Ltd.
July 08, 2019
DetNet Flow Information Model
draft-ietf-detnet-flow-information-model-04
Abstract
This document describes 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 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
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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 January 9, 2020.
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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2. Non Goals . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Terms Used in This Document . . . . . . . . . . . . . . . 5
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 6
2.3. Naming Conventions . . . . . . . . . . . . . . . . . . . 6
2.4. Requirements Language . . . . . . . . . . . . . . . . . . 7
3. DetNet Domain and its Modeling . . . . . . . . . . . . . . . 7
3.1. DetNet Service Overview . . . . . . . . . . . . . . . . . 7
3.2. Reference Points Used in Modeling . . . . . . . . . . . . 7
3.3. Information Elements . . . . . . . . . . . . . . . . . . 8
4. App-flow Related Parameters . . . . . . . . . . . . . . . . . 8
4.1. App-flow Characteristics . . . . . . . . . . . . . . . . 8
4.2. App-flow Requirements . . . . . . . . . . . . . . . . . . 9
5. DetNet Flow Related Parameters . . . . . . . . . . . . . . . 9
5.1. Management ID of the DetNet Flow . . . . . . . . . . . . 10
5.2. Payload type of the DetNet Flow . . . . . . . . . . . . . 10
5.3. Format of the DetNet Flow . . . . . . . . . . . . . . . . 10
5.4. Identification and Specification of DetNet Flows . . . . 10
5.4.1. DetNet MPLS Flow Identification and Specification . . 11
5.4.2. DetNet IP Flow Identification and Specification . . . 11
5.5. Traffic Specification of the DetNet Flow . . . . . . . . 11
5.6. Endpoints of the DetNet Flow . . . . . . . . . . . . . . 12
5.7. Rank of the DetNet Flow . . . . . . . . . . . . . . . . . 12
5.8. Status of the DetNet Flow . . . . . . . . . . . . . . . . 12
5.9. Requirements of the DetNet Flow . . . . . . . . . . . . . 13
5.9.1. Minimum Bandwidth of the DetNet Flow . . . . . . . . 14
5.9.2. Maximum Latency of the DetNet Flow . . . . . . . . . 14
5.9.3. Maximum Latency Variation of the DetNet Flow . . . . 14
5.9.4. Maximum Loss of the DetNet Flow . . . . . . . . . . . 14
5.9.5. Maximum Consequtive Loss of the DetNet Flow . . . . . 14
5.9.6. Maximum Misordering Tolerance of the DetNet Flow . . 14
5.10. BiDir requirement of the DetNet Flow . . . . . . . . . . 14
6. DetNet Service Related Parameters . . . . . . . . . . . . . . 15
6.1. Management ID of the DetNet service . . . . . . . . . . . 15
6.2. Delivery Type of the DetNet service . . . . . . . . . . . 15
6.3. Delivery Profile of the DetNet Service . . . . . . . . . 15
6.3.1. Minimum Bandwidth of the DetNet Service . . . . . . . 16
6.3.2. Maximum Latency of the DetNet Service . . . . . . . . 16
6.3.3. Maximum Latency Variation of the DetNet Service . . . 16
6.3.4. Maximum Loss of the DetNet Service . . . . . . . . . 16
6.3.5. Maximum Consequtive Loss of the DetNet Service . . . 16
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6.3.6. Maximum Misordering Tolerance of the DetNet Service . 16
6.4. Connectivity Type of the DetNet Service . . . . . . . . . 16
6.5. BiDir requirement of the DetNet Service . . . . . . . . . 17
6.6. Rank of the DetNet Service . . . . . . . . . . . . . . . 17
6.7. Status of the DetNet Service . . . . . . . . . . . . . . 17
7. Flow Specific Operations . . . . . . . . . . . . . . . . . . 18
7.1. Join Operation . . . . . . . . . . . . . . . . . . . . . 18
7.2. Leave Operation . . . . . . . . . . . . . . . . . . . . . 19
7.3. Modify Operation . . . . . . . . . . . . . . . . . . . . 19
8. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
10. Security Considerations . . . . . . . . . . . . . . . . . . . 19
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
11.1. Normative References . . . . . . . . . . . . . . . . . . 19
11.2. Informative References . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction
A Deterministic Networking (DetNet) service 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. DetNet and TSN have common architecture as
expressed in [IETFDetNet] and [I-D.ietf-detnet-architecture]. The
DetNet service is provided for DetNet flows via the DetNet service
and forwarding sub-layers.
DetNet service is IP or MPLS and DetNet is currently defined for IP
and MPLS networks as shown in Figure 1 based on Figure 2 and Figure 3
of [I-D.ietf-detnet-data-plane-framework]. A DetNet flow includes
one or more App-flow(s) as payload. App-flows can be Ethernet, MPLS,
or IP flows, which impacts what header fields are use in order to
identify a flow. DetNet flows are created by DetNet encapsulation of
App-flow(s) (e.g., with added MPLS labels, etc.). In some scenarios
App-flow and DetNet flow look similar on the wire (e.g., 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
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As shown in Figure 1 as per [I-D.ietf-detnet-data-plane-framework] a
DetNet flow can be treated as an application level flow (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
distinguished:
o Flow models 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).
o Service models describe characteristics of services being provided
for data flows over a network. These models can be treated as a
network operator independent information model.
o Configuration models describe in detail the settings required on
network nodes to serve a data flow properly.
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)
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DetNet flow and service information model is based on
[I-D.ietf-detnet-architecture] and on the concept of data model
specified by [IEEE8021Qcc]. Furthermore, the starting point of the
DetNet flow information model was the flow identification
possibilities described in [IEEE8021CB], which is used by
[IEEE8021Qcc] as well. In addition to TSN data model, [IEEE8021Qcc]
also specifies configuration of TSN features (e.g., traffic
scheduling specified by [IEEE8021Qbv]). Due to the common
architecture and flow model, configuration features can be leveraged
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 it is expressed in the Charter [IETFDetNet], the DetNet WG
collaborates with IEEE 802.1 TSN in order to define a common
architecture for both Layer 2 and Layer 3, which is beneficial for
various reasons, e.g., in order to simplify implementations. The
flow and service information models should be also aligned along
those lines. Therefore, the DetNet flow and service information
models described in this document are based on [IEEE8021Qcc], which
is an amendment to [IEEE8021Q].
This document intends to specify flow and service information models
only.
1.2. Non Goals
This document (this revision) does not intend to specify either flow
data model or DetNet configuration. From these aspects, the goals of
this document differ from the goals of [IEEE8021Qcc], which also
specifies data model and configuration of certain TSN features.
2. Terminology
2.1. Terms Used in This Document
This document uses the terminology established in the DetNet
architecture [I-D.ietf-detnet-architecture] and the the DetNet Data
Plane Framework [I-D.ietf-detnet-data-plane-framework]. The reader
is assumed to be familiar with these documents and any terminology
defined therein. The DetNet <=> TSN dictionary of
[I-D.ietf-detnet-architecture] is used to perform translation from
[IEEE8021Qcc] to this document.
The following terminology is used according to
[I-D.ietf-detnet-architecture]:
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App-flow The payload (data) carried over a DetNet service.
DetNet flow A DetNet flow is a sequence of packets which 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 DetNet flow, where it starts.
Networking technology specific encapsulation may be
added here to the served App-flow(s).
DN Egress Reference point for DetNet flow, where it terminates.
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.
o Names SHOULD be descriptive.
o Names MUST start with uppercase letters.
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o Composed names MUST use capital letters for the first letter of
each component. All other letters are lowercase, even for
acronyms. Exceptions are made for acronyms containing a mixture
of lowercase and capital letters, such as IPv6. Examples are
SourceMacAddress and DestinationIPv6Address.
2.4. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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.
Figure 5. and Figure 8. in [I-D.ietf-detnet-architecture] show the
DetNet service related reference points and main components.
3.2. Reference Points Used in Modeling
From 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
have reference points named as DN Ingress (where it starts) and DN
Egress (where it 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.
All reference points are assumed in this document 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).
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3.3. Information Elements
The DetNet flow information model and the service model relies on
three groups of information elements:
o App-flow related paramaters: they describe the App-flow
characteristics (e.g., identification, encapsulation, traffic
specification, endpoints, status, etc.) and the App-flow
requirements (e.g., delay, loss, etc.).
o DetNet flow related parameters: they describe the DetNet flow
characteristics (e.g., identification, format, traffic
specification, endpoints, rank, etc.).
o DetNet service related parameters: they 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 App-flows
(N:1 mapping). During DetNet aggregation the aggregated DetNet flows
are treated as App-flows and the aggregate is the DetNet flow, which
provides N:1 mapping. Similarly, there is a M:1 relationship of
DetNet flow(s) and a DetNet Service.
4. App-flow Related Parameters
Deterministic service is required by time/loss sensitive
application(s) running on an end system during communication with its
peer(s). Such a data exchange has various requirements on delay and/
or loss parameters.
4.1. App-flow Characteristics
App-flow characteristics are described with the following parameters:
o FlowID: it is a unique (management) identifier of the App-flow.
It can be used to define the N:1 mapping of App-flows to a DetNet
flow.
o FlowType: it is set according to the encapsulation format of the
flow. It can be Ethernet (TSN), MPLS, or IP.
o DataFlowSpecification: it is a flow descriptor, defining which
packets belongs to a flow using, e.g., FlowType specific packet
header fields like src-addr, dst-addr, label, VLAN-ID, etc.
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o TrafficSpecification: it is a flow descriptor, defining traffic
parameters like packet size, interval, and max. packets per
interval.
o FlowEndpoints: it defines the start and termination reference
points of the App-flow by pointing to the source interface/node
and destination interface(s)/node(s).
o FlowStatus: it provides the status of the App-flow with respect to
the establishment of the flow by the network, e.g., ready, failed,
etc.
o FlowRank: it provides the rank of this flow relative to other
flows in the network.
4.2. App-flow Requirements
App-flow requirements are described with the following parameters:
o FlowRequirements: it defines the requirement of the App-flow
regarding bandwidth, latency, latency variation, loss, and
misorder tolerance.
o FlowBiDir: it defines the requirement of the App-flow whether it
has to be routed together with other App-flow(s) through the
network, e.g., to provide congruent paths in the two directions.
5. DetNet Flow Related Parameters
Data model specified by [IEEE8021Qcc] describes data flows using TSN
service as periodic flows with fix packet size (i.e., Constant Bit
Rate (CBR) flows) or with variable packet size. The same concept is
applyed for flows using DetNet service.
Latency and loss parameters are correlated because the effect of late
delivery can result data loss for an application. However, not all
applications require hard limits on both parameters (latency and
loss). For example, some real-time applications allow graceful
degradation if loss happens (e.g., sample-based processing, media
distribution). Some others may require high-bandwidth connections
that make the usage of techniques like packet replication
economically challenging or even impossible. Some applications may
not tolerate loss, but are not latency sensitive (e.g., bufferless
sensors). Time/loss sensitive applications may have somewhat special
requirements especially for loss (e.g., no loss in two consecutive
communication cycles; very low outage time, etc.).
DetNet flows have the following attributes:
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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:
o DnFlowRequirements (Section 5.9)
o 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 in DnFlowID. It can be
used to define the M:1 mapping of DetNet flows to a DetNet service.
5.2. Payload type of the DetNet Flow
DnPayloadType attribute is set according to encapsulated App-flow
format. The attribute can be Ethernet, MPLS, or IP.
5.3. Format of the DetNet Flow
DnFlowFormat attribute is set according to 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 DetNetw IP flows.
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5.4.1. DetNet MPLS Flow Identification and Specification
Identification of DetNet MPLS flows within the DetNet domain are used
in the service information model. The attributes are specific to the
MPLS forwarding paradigm within the DetNet domain
[I-D.ietf-detnet-mpls]. DetNetwork 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 (6-tuple) [I-D.ietf-detnet-ip]:
a. SourceIpAddress
b. DestinationIpAddress
c. IPv6FlowLabel
d. Dscp
e. Protocol
f. SourcePort
g. DestinationPort
5.5. Traffic Specification of the DetNet Flow
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
cannot be exceeded.
b. MaxPacketsPerInterval: the maximum number of packets that the
Ingress will transmit in one Interval.
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c. MaxPayloadSize: the maximum payload size that the Ingress will
transmit.
These attributes can be used to describe any type of traffic (e.g.,
CBR, VBR, etc.) and can be used during resource allocation to
represent worst case scenarios.
[[Editor's note (to be removed from a future revision): 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 d elay-and-loss sensitive).
Possible options how to extend DnTrafficSpecification attributes is
for further discussion. ]]
5.6. Endpoints of the DetNet Flow
DnFlowEndpoints attribute defines the starting and termination
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 UNI interface. For exampe for App-flows
with MPLS encapsulation defining an ingress node is more common when
per platform label space is used.
5.7. Rank of the DetNet Flow
DnFlowRank 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 dropped (i.e., removed from node configuration) if for example a
port of a node becomes oversubscribed (e.g., due to network re-
configuration).
5.8. Status of the DetNet Flow
DnFlowStatus provides the status of the DetNet flow with respect to
the establishment of the flow by the DetNet domain.
The DnFlowStatus SHALL include the following attributes:
a. DnIngressStatus is an enumeration for the status of the flow's
Ingress reference point:
* None: no Ingress.
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* 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 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. FailureCode: A non-zero code that specifies the problem if the
DetNet flow encounters a failure (e.g., packet replication and
elimination is requested but not possible, or DnIngressStatus is
Failed, or DnEgressStatus is Failed, or DnEgressStatus is
PartialFailed).
[[Editor's note (to be removed from a future revision): FailureCodes
to be defined for DetNet. Table 46-1 of [IEEE8021Qcc] describes TSN
failure codes.]]
5.9. Requirements of the DetNet Flow
DnFlowRequirements specifies requirements to ensure proper serving of
the DetNet flow.
The DnFlowRequirements includes the following attributes:
a. MinBandwidth
b. MaxLatency
c. MaxLatencyVariation
d. MaxLoss
e. MaxConsecutiveLossTolerance
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f. MaxMisordering
5.9.1. Minimum Bandwidth of the DetNet Flow
MinBandwidth is the minimum bandwidth that has to be guaranteed for
the DetNet flow.
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.
5.9.4. Maximum Loss of the DetNet Flow
MaxLoss defines the maximum Packet Loss Ratio (PLR) requirement for
the DetNet flow between the Ingress and Egress(es).
5.9.5. Maximum Consequtive Loss of the DetNet Flow
Some applications have special loss requirement, like
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 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.
5.10. BiDir requirement of the DetNet Flow
DnFlowBiDir attribute defines the requirement whether the served
packets have to be routed together with packets of other flows
through the DetNet domain, e.g., to provide congruent paths in the
two directions.
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6. DetNet Service Related Parameters
DetNet service have 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
A unique (management) identifier is needed for each DetNet service
within the DetNet domain. It is specified in DnServiceID. It can be
used to define the M:1 mapping of DetNet flows to a DetNet service.
6.2. Delivery Type of the DetNet service
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
DnServiceDeliveryProfile specifies delivery profile to ensure proper
serving of the DetNet flow.
The DnServiceDeliveryProfile includes the following attributes:
a. MinBandwidth
b. MaxLatency
c. MaxLatencyVariation
d. MaxLoss
e. MaxConsecutiveLossTolerance
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f. MaxMisordering
6.3.1. Minimum Bandwidth of the DetNet Service
MinBandwidth is the minimum bandwidth that has to be guaranteed for
the DetNet service.
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.
6.3.4. Maximum Loss of the DetNet Service
MaxLoss defines the maximum Packet Loss Ratio (PLR) parameter for the
DetNet service between the Ingress and Egress(es) of the DetNet
domain.
6.3.5. Maximum Consequtive Loss of the DetNet Service
Some applications have special loss requirement, like
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 is created by a
transport layer function (e.g., p2mp LSP). (Note: mp2mp connectivity
is a superposition of p2mp connections.)
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6.5. BiDir requirement of the DetNet Service
DnServiceBiDir attribute defines the requirement whether the served
packets have to be routed together with packets of other service
instances through the DetNet domain, e.g., to provide congruent paths
in the two directions.
6.6. Rank of the DetNet Service
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.
6.7. Status of the DetNet Service
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.
The DnServiceStatus SHALL include 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 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.
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c. DnServiceFailureCode: A non-zero code that specifies the problem
if the DetNet service encounters a failure (e.g., packet
replication and elimination is requested but not possible, or
DnServiceIngressStatus is Failed, or DnServiceEgressStatus is
Failed, or DnServiceEgressStatus is PartialFailed).
[[Editor's note (to be removed from a future revision):
DnServiceFailureCodes to be defined for DetNet service. 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:
o 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.
o 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.
o DnFlowStatus: The status 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 (similarly to
App-flows at a Source or a Destination):
o Join: DN Ingress/DN Egress intends to join the flow.
o Leave: DN Ingress/DN Egress intends to leave the flow.
o Modify: DN Ingress/DN Egress intends to change the flow.
7.1. Join Operation
For the join operation, the DnFlowSpecification, DnFlowRank,
DnFlowEndpoint, and DnTrafficSpecification SHALL be included within
the DnIngress or DnEgress information group. For the join operation,
the DnServiceRequirements groups MAY be included.
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7.2. Leave Operation
For the leave operation, the DnFlowSpecification and DnFlowEndpoint
SHALL be included within the DnIngress or DnEgress information group.
7.3. Modify Operation
For the modify operation, the DnFlowSpecification, DnFlowRank,
DnFlowEndpoint, and DnTrafficSpecification SHALL be included within
the DnIngress or DnEgress information group. For the join operation,
the DnServiceRequirements groups MAY be included.
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 to
initiate a change of flow spec while leaving the current flow is
operating until the change is accepted. If there is no linkage
between the Join and the Leave, then in 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. Via 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 DetNet flow information model and service
information model for DetNet IP networks and DetNet MPLS networks.
9. IANA Considerations
N/A.
10. Security Considerations
N/A.
11. References
11.1. Normative References
[I-D.ietf-detnet-architecture]
Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", draft-ietf-
detnet-architecture-13 (work in progress), May 2019.
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[I-D.ietf-detnet-ip]
Varga, B., Farkas, J., Berger, L., Fedyk, D., Malis, A.,
Bryant, S., and J. Korhonen, "DetNet Data Plane: IP",
draft-ietf-detnet-ip-01 (work in progress), July 2019.
[I-D.ietf-detnet-mpls]
Varga, B., Farkas, J., Berger, L., Fedyk, D., Malis, A.,
Bryant, S., and J. Korhonen, "DetNet Data Plane: MPLS",
draft-ietf-detnet-mpls-01 (work in progress), July 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC6003] Papadimitriou, D., "Ethernet Traffic Parameters",
RFC 6003, DOI 10.17487/RFC6003, October 2010,
<https://www.rfc-editor.org/info/rfc6003>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
11.2. Informative References
[I-D.ietf-detnet-data-plane-framework]
Varga, B., Farkas, J., Berger, L., Fedyk, D., Malis, A.,
Bryant, S., and J. Korhonen, "DetNet Data Plane
Framework", draft-ietf-detnet-data-plane-framework-01
(work in progress), July 2019.
[IEEE8021CB]
IEEE Standards Association, "IEEE Std 802.1CB-2017 IEEE
Standard for Local and metropolitan area networks - Frame
Replication and Elimination for Reliability", 2017,
<https://ieeexplore.ieee.org/document/8091139/>.
[IEEE8021Q]
IEEE Standards Association, "IEEE Std 802.1Q-2018 IEEE
Standard for Local and metropolitan area networks -
Bridges and Bridged Networks", 2018,
<https://ieeexplore.ieee.org/document/8403927>.
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[IEEE8021Qbv]
IEEE Standards Association, "IEEE Std 802.1Qbv-2015 IEEE
Standard for Local and metropolitan area networks -
Bridges and Bridged Networks - Amendment 25: Enhancements
for Scheduled Traffic", 2015,
<https://ieeexplore.ieee.org/document/7572858/>.
[IEEE8021Qcc]
IEEE Standards Association, "IEEE Std 802.1Qcc-2018: IEEE
Standard for Local and metropolitan area networks -
Bridges and Bridged Networks -- Amendment 31: Stream
Reservation Protocol (SRP) Enhancements and Performance
Improvements", 2018,
<https://ieeexplore.ieee.org/document/8514112/>.
[IEEE8021TSN]
IEEE 802.1, "IEEE 802.1 Time-Sensitive Networking (TSN)
Task Group", <http://www.ieee802.org/1/pages/tsn.html>.
[IETFDetNet]
IETF, "IETF Deterministic Networking (DetNet) Working
Group", <https://datatracker.ietf.org/wg/detnet/charter/>.
Authors' Addresses
Janos Farkas
Ericsson
Magyar tudosok korutja 11
Budapest 1117
Hungary
Email: janos.farkas@ericsson.com
Balazs Varga
Ericsson
Magyar tudosok korutja 11
Budapest 1117
Hungary
Email: balazs.a.varga@ericsson.com
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Rodney Cummings
National Instruments
11500 N. Mopac Expwy
Bldg. C
Austin, TX 78759-3504
USA
Email: rodney.cummings@ni.com
Yuanlong Jiang
Huawei Technologies Co., Ltd.
Bantian, Longgang district
Shenzhen 518129
China
Email: jiangyuanlong@huawei.com
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