DetNet J. Farkas
Internet-Draft B. Varga
Intended status: Standards Track Ericsson
Expires: September 12, 2019 R. Cummings
National Instruments
Y. Jiang
Huawei Technologies Co., Ltd.
March 11, 2019
DetNet Flow Information Model
draft-ietf-detnet-flow-information-model-03
Abstract
This document describes flow and service information model for
Deterministic Networking (DetNet). The DetNet service is provided
either for a Layer 3 or a Layer 2 flow. This document provides
DetNet flow and service information model both for Layer 3 and Layer
2 flows in an integrated fashion.
Status of This Memo
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This Internet-Draft will expire on September 12, 2019.
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Table of Contents
1. ToDo list . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2. Non Goals . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Conventions Used in This Document . . . . . . . . . . . . . . 5
4. Terminology and Definitions . . . . . . . . . . . . . . . . . 5
5. Naming Conventions . . . . . . . . . . . . . . . . . . . . . 6
6. Service model . . . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Service overview . . . . . . . . . . . . . . . . . . . . 6
6.2. Service parameters . . . . . . . . . . . . . . . . . . . 6
6.3. Reference Points . . . . . . . . . . . . . . . . . . . . 8
6.4. Service scenarios . . . . . . . . . . . . . . . . . . . . 9
7. End System and DetNet domain . . . . . . . . . . . . . . . . 9
8. DetNet flows . . . . . . . . . . . . . . . . . . . . . . . . 11
8.1. Identification and Specification of Flows . . . . . . . . 11
8.1.1. IP flow Identification and Specification at UNI . . . 12
8.1.2. L2 Flow Identification and Specification at UNI . . . 12
8.1.3. DetNet Flow Identification and Specification . . . . 13
8.2. Traffic Specification . . . . . . . . . . . . . . . . . . 13
8.3. Flow Rank . . . . . . . . . . . . . . . . . . . . . . . . 15
9. Source . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
10. Destination . . . . . . . . . . . . . . . . . . . . . . . . . 16
11. Common Attributes of Source and Destination . . . . . . . . . 16
11.1. End System Interfaces . . . . . . . . . . . . . . . . . 16
11.2. Interface Capabilities . . . . . . . . . . . . . . . . . 16
11.3. User to Network Requirements . . . . . . . . . . . . . . 17
12. Ingress . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
13. Egress . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
14. DetNet Domain . . . . . . . . . . . . . . . . . . . . . . . . 18
14.1. DetNet Domain Capabilities . . . . . . . . . . . . . . . 19
15. Flow-status . . . . . . . . . . . . . . . . . . . . . . . . . 19
15.1. Status Info . . . . . . . . . . . . . . . . . . . . . . 20
15.2. Interface Configuration . . . . . . . . . . . . . . . . 21
15.3. Failed Interfaces . . . . . . . . . . . . . . . . . . . 21
16. Service Rank . . . . . . . . . . . . . . . . . . . . . . . . 22
17. Service-status . . . . . . . . . . . . . . . . . . . . . . . 22
18. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
19. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
20. Security Considerations . . . . . . . . . . . . . . . . . . . 22
21. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
21.1. Normative References . . . . . . . . . . . . . . . . . . 23
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21.2. Informative References . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
1. ToDo list
These further actions are due on the draft:
o Align with updated architecture and data plane documents (partly
done).
o App-flow parameters will not be defined in detail (add references
only, e.g., 802.1Qcc). We focus on DetNet flows.
o Clarification on relationship between DetNet flow model and DetNet
service model.
o Parameter set needs finalization, some re-org of the set may be
needed.
o Sort out which parameter belongs to DetNet flow model and which to
DetNet service model.
o Clarify relationship between App-flow and DetNet flow (N:1 vs
1:1).
2. 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. The DetNet service is provided either for
a Layer 3 (L3) flow or a Layer 2 (L2) flow by an IP/MPLS network,
see, e.g., [I-D.ietf-detnet-dp-sol-mpls]. Similarly, Time-Sensitive
Networking (TSN) [IEEE8021TSN]) can be used for L2 flows in a bridged
network. DetNet and TSN have common architecture as expressed in
[IETFDetNet] and [I-D.ietf-detnet-architecture]. DetNet service can
be leveraged both by L3 and L2 flows, i.e., by DetNet L3 flows and
DetNet L2 flows. Therefore, the DetNet flow and service information
model provided by this document covers both DetNet L3 flows and
DetNet L2 flows 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).
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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 1.
User Network Operator
flow/service
/\ info model +---+
/ \ <---------------> | X | management/control
---- +-+-+ plane entity
^
| configuration
| info model
+------------+
v | |
+-+ | v Network
+-+ v +-+ nodes
+-+ +-+
+-+
Figure 1: Usage of Information models (flow, service and
configuration)
DetNet flow and service information model is based on
[I-D.ietf-detnet-architecture] and on the data model specified by
[IEEE8021Qcc]. Furthermore, the DetNet flow information model relies
on 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.
Based on the DetNet architecture [I-D.ietf-detnet-architecture] (see
Section 4), this document (this revision) only considers the
Centralized Network / Distributed User Model out of the models
specified by [IEEE8021Qcc]. That is, there is a User-Network
Interface (UNI) between an end system and a network. Furthermore,
there is a central entity for the control of the network. For
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instance, the central entity implements a Path Computation Element
(PCE) for the calculation and establishment of paths needed for
packet replication and elimination, if any.
2.1. 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 common along those
lines. As the TSN flow information/data model specified by
[IEEE8021Qcc] is mature, 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.
2.2. 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.
3. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
The lowercase forms with an initial capital "Must", "Must Not",
"Shall", "Shall Not", "Should", "Should Not", "May", and "Optional"
in this document are to be interpreted in the sense defined in
[RFC2119], but are used where the normative behavior is defined in
documents published by SDOs other than the IETF.
4. Terminology and Definitions
This document uses the terminology established in Section 2 of the
DetNet architecture document [I-D.ietf-detnet-architecture]. The
DetNet <=> TSN dictionary of [I-D.ietf-detnet-architecture] is used
to perform translation from [IEEE8021Qcc] to this document.
Application level flows (app-flow) can be L2 or L3 flows, what may
impact what header fields are use in order to identify a flow.
DetNet flows are created by proper DetNet encapsulation of app-
flow(s) (e.g., with added MPLS labels, etc.). In some scenarios App-
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flow and DetNet flow looks similar on the wire (e.g., L3 App-flow
over a DetNet IP network).
5. 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.
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.
6. Service model
6.1. 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.
The simplest DetNet service is to provide bridging over the DN domain
(i.e., tunneling for L2), where the connected hosts are in the same
broadcast (BC) domain. Forwarding over the DetNet domain is based on
L2 (MAC) addresses (i.e. dst-MAC). Somewhat more sophisticated is
DetNet Routing service that provides routing, so available only for
L3 hosts that are in different BC domains. Forwarding over the
DetNet domain is based on L3 (IP) addresses (i.e. dst-IP).
Figure 5. and Figure 8. in [I-D.ietf-detnet-architecture] show the
DetNet service related reference points and main components.
6.2. Service parameters
A DetNet network receives DetNet flows via a UNI as shown in Figure 5
in [I-D.ietf-detnet-architecture]. The DetNet network connects the
UNIs via tunnels in order to provide DetNet service as shown in
Figure 8 in [I-D.ietf-detnet-architecture].
The DetNet service attributes are the following:
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o Service type
It is the flow type (L2 or L3) using the DetNet service.
o Bandwidth
It is the minimum bandwidth guaranteed for the DetNet service.
o Delay parameters
The are two delay parameters for a DetNet service:
* Maximum latency, which is the maximum end-to-end one-way
latency for the DetNet service.
* Packet Delay Variation (PDV), which is the difference between
the minimum and the maximum end-to-end one-way latency. The
PDV parameter describes the maximum packet delay variation for
the DetNet service. (Note that PDV is sometimes referred to as
jitter.)
o Loss parameters
* The maximum Packet Loss Ratio (PLR) parameter describes the
maximum packet loss ratio for the DetNet service between the
edges of the DetNet network.
* Some applications have special loss requirement. 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 based on
sequence number.
o Maximum allowed misordering
Maximum allowed misordering describes the tolerable maximum number
of packets that can be received out of order. The maximum allowed
misordering can be measured based on sequence number. The value
zero for the maximum allowed misordering indicates that in order
delivery is required, misordering cannot be tolerated.
o Connectivity type
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.)
o Service rank
Service rank provides the rank of a service instance relative to
other services in the network. Rank is used by the network in
case of network resource limitation scenarios.
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6.3. Reference Points
From service model design perspective a fundamental question is the
location of the service endpoints, i.e., where the service starts and
ends.
+--------+
| |
| X X |
| ____ |
| / \ |
| |
|/\/\/\/\|
To be ADDED
404 Not Found
Figure 2: FIGURE Placeholder Reference Points
Note: Further discussion is needed based on data plane encapsulation
results what reference points should be defined. Only some possible
examples listed here:
o App-flow endpoint: End system's internal reference point for the
native data flow.
o DetNet-UNI: UNI interface ("U") on a DetNet edge node.
o DetNet-NNI: NNI interface ("N") between DetNet domains.
[[NOTE: Contributions are welcome whether we should define or
distinguish internal reference point(s) for DetNet-aware end-systems
as well. ]]
DetNet-UNI and DetNet-NNI are assumed in this document to be packet-
based reference points and provide connectivity over the packet
network and between domains. A DetNet-UNI may add networking
technology specific encapsulation to the data flow in order to
transport it over the network.
[[NOTE: Differences between the service over end-systems internal
reference points and DetNet-UNI is for further discussions. For
example, in-order delivery is expected in end system internal
reference points, whereas it is considered optional over the DetNet-
UNI. ]]
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6.4. Service scenarios
Using the above defined reference points, two major service scenarios
can be identified:
o End-to-End-Service: the service reaches out to final source or
destination nodes, so it is an e2e service between application
hosting devices (end systems).
o DetNet-Service: the service connects networking islands, so it is
a service between the borders of network domain(s).
[[NOTE: we may consider to define further scenarios based on the
result of reference point related discussions. ]]
7. End System and DetNet domain
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.
The DetNet architecture [I-D.ietf-detnet-architecture] distinguishes
two kinds of end systems: Source and Destination. The same
distinction is applied for the DetNet flow information model. In
addition to the end systems interested in a flow, the status
information of the flow is also important. Therefore, the DetNet
flow information model relies on three high level groups:
o Source: an end system capable of sourcing a DetNet flow. The
Source information group includes elements that specify the Source
for a single flow. This information group is applied from the
user to the network.
o Destination: an end system that is a destination of a DetNet flow.
The Destination information group includes elements that specify
the Destination for a single flow. This information group is
applied from the user to the network.
o Flow-Status: the status of a DetNet flow. 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. This information group informs the user whether or not
the flow is ready for use.
From service perspective two kinds of edge nodes can be
distinguished: Ingress and Egress. In addition the technology of the
DetNet domain and the status of the service are also important.
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Therefore, the DetNet service information model relies on four high
level groups:
o Ingress: an edge system receiving a DetNet flow from a Source.
The Ingress information group includes elements that specify the
entry point for a single flow. This information group is applied
from the network to the user.
o Egress: an edge system sending traffic towards a Destination of a
DetNet flow. The Egress information group includes elements that
specify the egress point for a single flow. This information
group is applied from the network to the user.
o DetNet Domain: an administrative domain providing the DetNet
service. The DetNet domain information group includes elements
that specify the forwarding capabilities and methods for a single
flow. This information group is applied within the network.
o Service-Status: the status of a DetNet service. The status
information group includes elements that specify the status of the
service specific state of the network. This information group is
applied from the network to the user. This information group
informs the user whether or not the service is ready for use.
There are three operations for each flow with respect to a Source or
a Destination (and an Ingress or an Egress):
o Join: Source/Destination request to join the flow.
o Leave: Source/Destination request to leave the flow.
o Modify: Source/Destination request to change the flow.
Modify operation can be considered to address cases when a flow is
slightly changed, e.g., only MaxPayloadSize (Section 8.2) 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 central entity has to assume that the
resources committed to the current flow are in use. Via Modify the
central 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 control-plane
limitations.
As the DetNet UNI can provide service for both L3 and L2 app-flows,
end systems may not need to implement the L3 <=> L2 Transfer Function
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specified by [IEEE8021CB] (see, e.g., subclause 6.3; see also
subclause 46.1 in [IEEE8021Qcc]). A DetNet edge node may implement a
function similar to the Transfer Function, see, e.g., the Svc Proxy
in Figure 3 in [I-D.ietf-detnet-architecture].
8. DetNet flows
The app-flows leveraging DetNet service can be unicast or multicast
data flows of an application with constrained requirements on network
performance, e.g., low packet loss rate and/or latency. Flows can
require different connectivity types: point-to-point (p2p) or point-
to-multipoint (p2mp). The p2mp connectivity is created by a
transport layer function (e.g., p2mp LSP)
[I-D.ietf-detnet-dp-sol-mpls]. (Note that mp2mp connectivity is a
superposition of p2mp connections.)
Many flows using DetNet service are periodic with fix packet size
(i.e., Constant Bit Rate (CBR) flows), or periodic with variable
packet size.
Delay 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 (delay 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 delay 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.).
Flows have the following attributes:
a. DataFlowSpecification (Section 8.1)
b. TrafficSpecification (Section 8.2)
c. FlowRank (Section 8.3)
Flow attributes are described in the following sections.
8.1. Identification and Specification of Flows
Identification options for DetNet flows at the UNI and within the
DetNet domain are specified as follows; see Section 8.1.1 for DetNet
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L3 flows (at UNI), Section 8.1.2 for DetNet L2 flows (at UNI) and
Section 8.1.3 for DetNetwork flows (within the network).
8.1.1. IP flow Identification and Specification at UNI
L3 data flows can be identified and specified by the following
attributes:
a. SourceIpAddress
b. DestinationIpAddress
c. IPv6FlowLabel
d. Dscp
e. Protocol
f. SourcePort
g. DestinationPort
8.1.2. L2 Flow Identification and Specification at UNI
L2 data flows can be identified and specified by the following
attributes:
a. DestinationMacAddress
b. SourceMacAddress
c. Pcp
d. VlanId
e. EtherType
Note: The Multiple Stream Registration Protocol (MSRP) [IEEE8021Q]
uses StreamID to match Talker registrations with their corresponding
Listener registrations, i.e., to identify Streams (L2 TSN flows).
The StreamID includes the following subcomponents:
o A 48-bit MAC Address associated with the Talker sourcing the
stream to the bridged network.
o A 16-bit unsigned integer value, Unique ID, used to distinguish
among multiple streams sourced by the same Talker.
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8.1.3. DetNet Flow Identification and Specification
Identification of DetNet flows within the DetNet domain are used in
the service information model. The attributes are specific to the
forwarding paradigm within the DetNet domain. DetNetwork flows can
be identified and specified by the following attributes:
a. SourceIpAddress
b. DestinationIpAddress
c. IPv6FlowLabel
d. DSCP
e. Protocol
f. SourcePort
g. DestinationPort
h. MplsLabel
8.2. Traffic Specification
TrafficSpecification specifies how the Source transmits packets for
the flow. This is effectively the promise/request of the Source 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
Source will transmit in one Interval.
c. MaxPayloadSize: the maximum payload size that the Source will
transmit.
[[NOTE (to be removed from a future revision): 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. 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
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sensitive). Possible options how to extend TrafficSpecification
attributes is for further discussion. Identified options are
described in the following notes.]]
[[NOTE1: Based on the already defined attributes the most similar
additional attributes for VBR type flows can be defined as follows:
o AveragePacketsPerInterval: the average number of packets that the
Source will transmit in one Interval.
o AveragePayloadSize: the average payload size that the Source will
transmit.
]]
[[NOTE2: another alternative to deal better with various traffic
types can rely on [RFC6003], which describes the support of Metro
Ethernet Forum (MEF) Ethernet traffic parameters for using for
resource reservation purposes. Such a Bandwidth Profile can be also
adapted to describe the set of traffic parameters for a Detnet flow.
Committed Rate indicates the rate at which traffic commits to be sent
by the source (described in terms of the CIR (Committed Information
Rate) and CBS (Committed Burst Size) attributes.) Excess Rate
indicates the extent by which the traffic sent by the source exceeds
the committed rate. The Excess Rate is described in terms of the EIR
(Excess Information Rate) and EBS (Excess Burst Size) attributes. ]]
[[NOTE3: a third alternative is to define application based traffic
models such as [GPP22885] defines periodic and event-driven traffic
model, and 5G PPP work defines traffic model for MTC (Machine Type
Communication) use cases [I-D.ietf-detnet-use-cases]. Periodic
traffic type is usually for status update between devices or devices
transmit status report to a central unit in regular basis.
TrafficPeriod, defines the period of the status update message.
DataSize, defines the data size of the massage which is constant.
3GPP also defines approximately-periodic transmission with variations
on period and uncertainty in the time arrival of the packets. Event-
triggered traffic type corresponds traffic being triggered by an MTC
device event. MinIntervalBetweenEvent, defines the minimum interval
between two events. Event-triggered transmission will not happen all
the time, whenever an alert is sent, it waits until the issue being
solved to be able to send another alert. MaxPacketPerEvent, defines
the max number of packets within one message. ]]
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8.3. Flow Rank
FlowRank provides the rank of this flow relative to other flows in
the network. This rank is used to determine success/failure of flow
establishment. Rank (boolean) is used by the network 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 a port of a node becomes
oversubscribed (e.g., due to network reconfiguration). The true
value is more important than the false value (i.e., flows with false
are dropped first).
9. Source
The Source object specifies:
o The behavior of the Source for the flow (how/when the Source
transmits).
o The requirements of the Source from the network.
o The capabilities of the interface(s) of the Source.
The Source object includes the following attributes:
a. DataFlowSpecification (Section 8.1)
b. TrafficSpecification (Section 8.2)
c. FlowRank (Section 8.3)
d. EndSystemInterfaces (Section 11.1)
e. InterfaceCapabilities (Section 11.2)
f. UserToNetworkRequirements (Section 11.3)
For the join operation, the DataFlowSpecification, FlowRank,
EndSystemInterfaces, and TrafficSpecification SHALL be included
within the Source. For the join operation, the
UserToNetworkRequirements and InterfaceCapabilities groups MAY be
included within the Source.
For the leave operation, the DataFlowSpecification and
EndSystemInterfaces SHALL be included within the Source.
For the modify operation, the same object SHALL and MAY included as
for the join operation.
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10. Destination
The Destination object includes the following attributes:
a. DataFlowSpecification (Section 8.1)
b. EndSystemInterfaces (Section 11.1)
c. InterfaceCapabilities (Section 11.2)
d. UserToNetworkRequirements (Section 11.3)
For the join operation, the DataFlowSpecification and
EndSystemInterfaces SHALL be included within the Destination. For
the join operation, the UserToNetworkRequirements and
InterfaceCapabilities groups MAY be included within the Destination.
For the leave operation, the DataFlowSpecification and
EndSystemInterfaces SHALL be included within the Destination.
For the modify operation, the same object SHALL and MAY included as
for the join operation.
[[NOTE (to be removed from a future revision): Adding a general
EndpointRank? That would define the endpoint importance (source,
destination). It is only partly covered by FlowRank ... For
example, it could distinguish the importance of Destinations if the
flow cannot be provided for all Destinations.]]
11. Common Attributes of Source and Destination
Source and Destination end systems have the following common
attributes in addition to DataFlowSpecification (Section 8.1).
11.1. End System Interfaces
EndSystemInterfaces is a list of identifiers, one for each physical
interface (port) in the end system acting as a Source or Destination.
An interface is identified by an IP or a MAC address.
EndSystemInterfaces can refer also to logical sub-Interfaces if
supported by the end system, e.g., based on IfIndex parameter.
11.2. Interface Capabilities
InterfaceCapabilities specifies the network capabilities of all
interfaces (ports) contained in the EndSystemInterfaces object
(Section 11.1). These capabilities may be configured via the
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InterfaceConfiguration object (Section 15.2) of the Status object
(Section 15).
Note that an end system may have multiple interfaces with different
network capabilities. In this case, each interface should be
specified in a distinct top-level Source or Destination object (i.e.,
one entry in EndSystemInterfaces (Section 11.1)). Use of multiple
entries in EndSystemInterfaces is intended for network capabilities
that span multiple interfaces (e.g., packet replication and
elimination).";.
InterfaceCapabilities attributes:
a. SubInterfaceCapable (sub-interface capable)
b. PREF-Capable (packet replication and elimination capable)
c. POF-Capable (packet ordering capable)
[[NOTE (to be removed from a future revision): InterfaceCapabilities
attributes are to be defined. For information, [IEEE8021Qcc]
specifies the following attributes:
o VlanTagCapable (Customer VLAN Tag capable)
o CB-Capable (frame replication and elimination capable)
o CB-StreamIdenTypeList (a list of the optional Stream
Identification types supported by the interface as specified in
[IEEE8021CB].)
o CB-SequenceTypeList (a list of the optional Sequence Encode/Decode
types supported by the interface as specified in [IEEE8021CB].)
]]
11.3. User to Network Requirements
UserToNetworkRequirements specifies user requirements for the flow,
such as latency and reliability.
The UserToNetworkRequirements object includes the following
attributes:
a. MaxLatency
MaxLatency is the maximum latency from Source to Destination(s) for a
single packet of the flow. MaxLatency is specified as an integer
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number of nanoseconds. When this requirement is specified by the
Source, it must be satisfied for all Destinations. When this
requirement is specified by a Destination, it must be satisfied for
that particular Destination only. If the UserToNetworkRequirements
group is not provided within the Source or Destination object, then
value zero SHALL be used for this element. Value zero represents a
special use for the maximum latency requirement. Value zero locks-
down the initial latency that the network provides in the
AccumulatedLatency parameter of the Status object (Section 15) after
the successful configuration of the flow, such that any subsequent
increase in the latency beyond that initial value causes the flow to
fail.
[[NOTE-1 (to be removed from a future revision): Should we add a
parameter to specify the maximum packet loss rate that can be
tolerated for the flow?]]
[[NOTE-2 (to be removed from a future revision): TrafficSpecification
(Section 8.2) specifies the Peak Information Rate (PIR) of the flow,
which is a kind of user requirement to the network. Should we add
Committed Information Rate (CIR), i.e., the minimum rate the user
requests to be guaranteed for the flow by the network?]]
12. Ingress
Placeholder ...
13. Egress
Placeholder ...
14. DetNet Domain
The DetNet Domain may change the encapsulation of a DetNet L2 or L3
flow at the UNI. That impacts not only how a flow can be recognised
inside the DetNet domain but also the resource reservation
calculations.
The DetNet Domain object specifies:
o The behavior of the flow (how/when it is transmited).
o The requirements of the flow from the network.
o The capabilities of the DetNet domain.
The DetNet domain object includes the following attributes:
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a. DataFlowSpecification (Section 8.1)
b. TrafficSpecification (Section 8.2)
c. ServiceRank (Section 16)
d. DetnetDomainCapabilities (Section 14.1)
e. UserToNetworkRequirements (Section 11.3)
14.1. DetNet Domain Capabilities
DetnetDomainCapabilities specifies the network capabilities, which
can be used to provide DetNet service. DetNet Edge nodes may change
the encapsulation of a flow according to the data plane used inside
the DetNet domain.
DetnetDomainCapabilities object includes the following attributes:
a. EncapsulationFormat (data plane specific encapsulation)
b. PREF-Capable (packet replication and elimination capable)
15. Flow-status
The FlowStatus object is provided by the network each Source and
Destination of the flow. The Status object provides the status of
the flow with respect to the establishment of the flow by the
network. The Status object is delivered via the corresponding UNI to
each Source and Destination end system of the flow. The Status is
distinct for each Source or Destination because the
AccumulatedLatency and InterfaceConfiguration objects are distinct,
see below.
The Status object SHALL include the attributes a), b), c); and MAY
include attributes d), e):
a. DataFlowSpecification (Section 8.1)
b. StatusInfo (Section 15.1)
c. AccumulatedLatency (this section below)
d. InterfaceConfiguration (Section 15.2)
e. FailedInterfaces (Section 15.3)
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DataFlowSpecification identifies the flow for which status is
provided. DataFlowSpecification is described in (Section 8.1) If the
Status object is provided without a Source or Destination object in a
protocol message via a UNI, then the DataFlowSpecification object
SHALL be included within the Status object for both join and leave
operations. If the Status object immediately follows a Source or
Destination object in the protocol message, then the
DataFlowSpecification object is obtained from the Source/Destination
object, and therefore DataFlowSpecification is not required within
the Status object.
AccumulatedLatency provides the worst-case latency that a single
packet of the flow can encounter along its current path(s) in the
network. When provided to a Source, AccumulatedLatency is the worst-
case latency for all Destinations (worst path). AccumulatedLatency
is specified as an integer number of nanoseconds. Latency is
measured using the time at which the data frame's message timestamp
point passes the reference plane marking the boundary between the
network media and PHY. The message timestamp point is specified by
IEEE Std 802.1AS [IEEE8021AS] for various media. For a successful
Status, the network returns a value less than or equal to the
MaxLatency of the UserToNetworkRequirements (Section 11.3). If the
NumReplicationTrees of the UserToNetworkRequirements (Section 11.3)
is one, then the AccumlatedLatency SHALL provide the worst latency
for the current path from the Source to each Destination. If the
path is changed (e.g., due to rerouting), then the AccumulatedLatency
changes accordingly. If the NumReplicationTrees of the
UserToNetworkRequirements (Section 11.3) is greater than one,
AccumlatedLatency SHALL provide the worst latency for all paths in
use from the Source to each Destination.
15.1. Status Info
StatusInfo provides information regarding the status of a flow's
configuration in the network.
The StatusInfo object MAY include the following attributes:
a. SourceStatus is an enumeration for the status of the flow's
Source:
* None: no Source
* Ready: Source is ready
* Failed: Source failed
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b. DestinationStatus is an enumeration for the status of the flow's
Destinations:
* None: no Destination
* Ready: all Destinations are ready
* PartialFailed: One or more Destinations ready, and one or more
Listeners failed. The flow can be used if the Source is
Ready.
* Failed: All Destinations failed.
c. FailureCode: A non-zero code that specifies the problem if the
flow encounters a failure (e.g., packet replication and
elimination is requested but not possible, or SourceStatus is
Failed, or DestinationStatus is Failed, or DestinationStatus is
PartialFailed).
[[NOTE (to be removed from a future revision): FailureCodes to be
defined for DetNet. Table 46-1 of [IEEE8021Qcc] describes TSN
failure codes.]]
15.2. Interface Configuration
InterfaceConfiguration provides information about of interfaces in
the Source/Destination. This configuration related information
assists the network in meeting the requirements of the flow. The
InterfaceConfiguration object is according to the capabilities of the
interface. InterfaceConfiguration can be distinct for each Source or
Destination of each flow. If the InterfaceConfiguration object is
not provided within the Status object, then the network SHALL assume
zero elements as the default (no interface configuration).
The InterfaceConfiguration object MAY include one or more the
following attributes:
a. MAC or IP Address to identify the interface
b. DataFlowSpecification (Section 8.1)
15.3. Failed Interfaces
FailedInterfaces provides a list of one or more physical interfaces
(ports) in the failed node when a failure occurs in the network.
The FailedInterface object includes the following attributes:
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a. MAC or IP Address to identify the interface
b. InterfaceName
InterfaceName is the name of the interface (port) within the node.
This interface name SHALL be persistent, and unique within the node.
16. Service Rank
ServiceRank provides the rank of this service instance relative to
other services in the network. This rank is used to determine
success/failure of service instance establishment. Rank (boolean) is
used by the network to decide which services can and cannot exist
when network resources reach their limit. Rank is used to help to
determine which services can be dropped (i.e., removed from node
configuration) if a port of a node becomes oversubscribed (e.g., due
to network reconfiguration). The true value is more important than
the false value (i.e., services with false are dropped first).
[[NOTE: relationship between ServiceRank and FlowRank needs further
discussions. A 1:N relationship is assumed (a service instance can
serv multiple flows). This sub-section is considered to move to the
service related sections. ]]
17. Service-status
Placeholder ...
18. Summary
This document describes DetNet flow information model both for DetNet
L3 flows and DetNet L2 flows based on the TSN data model specified by
[IEEE8021Qcc]. This revision is extended with DetNet specific flow
information model elements.
19. IANA Considerations
N/A.
20. Security Considerations
N/A.
21. References
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21.1. Normative References
[I-D.ietf-detnet-architecture]
Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", draft-ietf-
detnet-architecture-11 (work in progress), February 2019.
[I-D.ietf-detnet-dp-sol-mpls]
Korhonen, J. and B. Varga, "DetNet MPLS Data Plane
Encapsulation", draft-ietf-detnet-dp-sol-mpls-01 (work in
progress), October 2018.
[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>.
21.2. Informative References
[GPP22885]
3GPP, "Study on LTE support for Vehicle-to-Everything
(V2X) services",
<http://www.3gpp.org/DynaReport/22885.html>.
[I-D.ietf-detnet-use-cases]
Grossman, E., "Deterministic Networking Use Cases", draft-
ietf-detnet-use-cases-20 (work in progress), December
2018.
[IEEE8021AS]
IEEE 802.1, "IEEE 802.1AS-2011: IEEE Standard for Local
and metropolitan area networks - Timing and
Synchronization for Time-Sensitive Applications in Bridged
Local Area Networks", 2011,
<http://standards.ieee.org/getieee802/
download/802.1AS-2011.pdf>.
[IEEE8021CB]
IEEE 802.1, "IEEE P802.1CB: IEEE Draft Standard for Local
and metropolitan area networks - Frame Replication and
Elimination for Reliability", 2017,
<http://www.ieee802.org/1/pages/802.1cb.html>.
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[IEEE8021Q]
IEEE 802.1, "IEEE 802.1Q-2014: IEEE Standard for Local and
metropolitan area networks - Bridges and Bridged
Networks", 2014, <http://standards.ieee.org/getieee802/
download/802-1Q-2014.pdf>.
[IEEE8021Qbv]
IEEE 802.1, "IEEE 802.1Qbv-2015: IEEE Standard for Local
and metropolitan area networks - Bridges and Bridged
Networks -- Amendment 25: Enhancements for Scheduled
Traffic", 2015, <https://standards.ieee.org/findstds/
standard/802.1Qbv-2015.html>.
[IEEE8021Qcc]
IEEE 802.1, "IEEE P802.1Qcc-2015: IEEE Draft Standard for
Local and metropolitan area networks - Bridges and Bridged
Networks -- Amendment: Stream Reservation Protocol (SRP)
Enhancements and Performance Improvements", 2017,
<http://www.ieee802.org/1/pages/802.1cc.html>.
[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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