Internet DRAFT - draft-ietf-detnet-flow-information-model
draft-ietf-detnet-flow-information-model
DetNet B. Varga
Internet-Draft J. Farkas
Intended status: Informational Ericsson
Expires: July 28, 2021 R. Cummings
National Instruments
Y. Jiang
Huawei Technologies Co., Ltd.
D. Fedyk
LabN Consulting, L.L.C.
January 24, 2021
DetNet Flow and Service Information Model
draft-ietf-detnet-flow-information-model-14
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
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on July 28, 2021.
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document authors. All rights reserved.
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to this document. Code Components extracted from this document must
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2. Non Goals . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1. Terms Used in This Document . . . . . . . . . . . . . . . 6
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 6
2.3. Naming Conventions . . . . . . . . . . . . . . . . . . . 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 . . . . . . . . . . . . . . . . . 13
5.8. Status of the DetNet Flow . . . . . . . . . . . . . . . . 13
5.9. Requirements of the DetNet Flow . . . . . . . . . . . . . 14
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 Consecutive Loss of the DetNet Flow . . . . . 14
5.9.6. Maximum Misordering Tolerance of the DetNet Flow . . 15
5.10. BiDir requirement of the DetNet Flow . . . . . . . . . . 15
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 . . . . . . . . . 16
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
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6.3.5. Maximum Consecutive Loss of the DetNet Service . . . 16
6.3.6. Maximum Misordering Tolerance of the DetNet Service . 17
6.4. Connectivity Type of the DetNet Service . . . . . . . . . 17
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 . . . . . . . . . . . . . . . . . . . . . 19
7.2. Leave Operation . . . . . . . . . . . . . . . . . . . . . 19
7.3. Modify Operation . . . . . . . . . . . . . . . . . . . . 19
8. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
10. Security Considerations . . . . . . . . . . . . . . . . . . . 20
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
11.1. Normative References . . . . . . . . . . . . . . . . . . 20
11.2. Informative References . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
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 based on Figure 2 and
Figure 3 of [RFC8938]. IEEE 802.1 Time Sensitive Networking (TSN)
utilizes Ethernet and is defined over Ethernet networks. A DetNet
flow includes one or more App-flow(s) 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
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DetNet encapsulation of App-flow(s) (e.g., MPLS labels, IP 6-tuple
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
As shown in Figure 1 as per [RFC8938] 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 be
distinguished:
o Flow 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).
o Service models that 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 that describe in detail the settings required
on network nodes to provide a data flow proper service.
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.
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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)
DetNet flow and service information model is based on [RFC8655] and
on the concept of 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 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 [IETFDetNet] Charter, the DetNet WG collaborates
with IEEE 802.1 TSN in order to define a common architecture for both
Layer 2 and Layer 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.
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The DetNet specific YANG data model is described in
[I-D.ietf-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 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 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 termination 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.
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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 Descriptive names are used.
o Names start with uppercase letters.
o Composed names 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. 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.
Figure 5 and Figure 8 in [RFC8655] 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
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.
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
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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 model relies on
three groups of information elements:
o 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.).
o DetNet flow related parameters: these describe the DetNet flow
characteristics (e.g., identification, format, traffic
specification, endpoints, rank, etc.).
o 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 Deterministic 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:
o FlowID: 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: set by the encapsulation format of the flow. It can be
Ethernet (TSN), MPLS, or IP.
o 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.
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o TrafficSpecification: a flow descriptor, defining traffic
parameters such as packet size, transmission time interval, and
maximum packets per time interval.
o FlowEndpoints: delineate 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: indicates the status of the App-flow with respect to
the establishment of the flow by the connected network, e.g.,
ready, failed, etc.
o 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:
o FlowRequirements: defines the attributes of the App-flow regarding
bandwidth, latency, latency variation, loss, and misordering
tolerance.
o 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
Bit Rate (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, media
distribution). Some other applications may require high-bandwidth
connections that make use of packet replication techniques which are
economically challenging or even impossible. Some applications may
not tolerate loss, but are not delay sensitive (e.g., bufferless
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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:
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 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 DetNetw IP flows.
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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 [I-D.ietf-detnet-mpls]. 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 (attribute)
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. 6-tuple and use of wild cards for these
attributes are specified in [RFC8939].
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
is specified.
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.
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, 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,
then 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; and 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 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 how to extend DnTrafficSpecification
attributes is for further discussion.
5.6. Endpoints of the DetNet Flow
The 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
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received over a well defined UNI (User-to-Network Interface). For
example, 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
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 re-configuration). DnFlowRank
value 0 is the highest priority.
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 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 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: A non-zero 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, or DnEgressStatus is Failed, or DnEgressStatus is
PartialFailed).
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Defining FailureCodes for DetNet is out-of-scope in this document.
Table 46-1 of [IEEE8021Qcc] describes TSN failure codes.
5.9. Requirements of the DetNet Flow
DnFlowRequirements specifies requirements to ensure the service level
desired for the DetNet flow.
The 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 Ratio (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 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.
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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
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
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 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.
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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(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 Ratio (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 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.
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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: from 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
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 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.
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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.
c. DnServiceFailureCode: A non-zero 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, or DnServiceEgressStatus is
Failed, or DnServiceEgressStatus is PartialFailed).
Defining DnServiceFailureCodes for DetNet service is out-of-scope in
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:
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.
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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 are included within the
DnIngress or DnEgress information group. 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 group.
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 is
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 model.
9. IANA Considerations
N/A.
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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 [I-D.ietf-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
[I-D.ietf-detnet-mpls]
Varga, B., Farkas, J., Berger, L., Malis, A., Bryant, S.,
and J. Korhonen, "DetNet Data Plane: MPLS", draft-ietf-
detnet-mpls-13 (work in progress), October 2020.
[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/>.
[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>.
11.2. Informative References
[I-D.ietf-detnet-security]
Grossman, E., Mizrahi, T., and A. Hacker, "Deterministic
Networking (DetNet) Security Considerations", draft-ietf-
detnet-security-13 (work in progress), December 2020.
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[I-D.ietf-detnet-yang]
Geng, X., Chen, M., Ryoo, Y., Fedyk, D., Rahman, R., and
Z. Li, "Deterministic Networking (DetNet) Configuration
YANG Model", draft-ietf-detnet-yang-09 (work in progress),
November 2020.
[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>.
[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/>.
[IETFDetNet]
IETF, "IETF Deterministic Networking (DetNet) Working
Group", <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
Balazs Varga
Ericsson
Magyar tudosok korutja 11
Budapest 1117
Hungary
Email: balazs.a.varga@ericsson.com
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Janos Farkas
Ericsson
Magyar tudosok korutja 11
Budapest 1117
Hungary
Email: janos.farkas@ericsson.com
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
Don Fedyk
LabN Consulting, L.L.C.
Email: dfedyk@labn.net
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