Draft: draft-ietf-detnet-data-plane-framework

Commentary: IESG review comment resolutions in this version : DONE   , IANA , ( 03 - 12 ) , OK   , ( 03 - 15 ) , Ready with Nits Yoshifumi Nishida , ( 04 - 07 ) , Ready with Nits   ( 04 - 12 ) , Editorial nits mostly   , ( 04 - 15 ) , Editorial comments TO BE DISCUSSED :   , ( 03 - 13 ) , Ready with Issues ( Ready , as soon as I - D.ietf - detnet - security is reviewed and becomes an RFC . ) 
 reviewed in April 22 meeting
Paragraph (version A):
This document describes the concepts needed by any DetNet data plane
specification and provides considerations for any corresponding
implementation.  It covers the building blocks that provide the
DetNet service, the DetNet service sub-layer and the DetNet
forwarding sub-layer functions as described in the DetNet
Architecture.
Paragraph (version B):
This document describes the concepts needed by any DetNet data plane
specification (i.e., the DetNet-specific use of packet header fields)
and provides considerations for any corresponding implementation.  It
covers the building blocks that provide the DetNet service, the
DetNet service sub-layer and the DetNet forwarding sub-layer
functions as described in the DetNet Architecture.
Paragraph (version A):
As part of the service sub-layer functions, this document describes
typical DetNet node data plane operation.  It describes the function
and operation of the Packet Replication (PRF) Packet Elimination
(PEF) and the Packet Ordering (POF) functions within the service sub-
layer.  Furthermore, it also describes the forwarding sub-layer.
Paragraph (version A):
DetNet flows may be carried over network technologies that can
provide the DetNet required service characteristics.  For example,
DetNet MPLS flows can be carried over IEEE 802.1 Time Sensitive
Network (TSN) IEEE802.1TSNTG sub-networks.  However, IEEE 802.1 TSN
support is not required in DetNet.  TSN frame preemption is an
example of a forwarding layer capability that is typically not
replicated in other forwarding technologies.  Most of DetNet benefits
can be gained by running over a data link layer that has not been
specifically enhanced to support all TSN capabilities but for certain
networks and traffic mixes delay and jitter performance may vary due
to the forwarding sub-layer intrinsic properties.
Paragraph (version A):
Different application flows (e.g., Ethernet, IP, etc.), can be mapped
on top of DetNet.  DetNet can optionally reuse header information
provided by, or shared with, applications.  An example of shared
header fields can be found in I-D.ietf-detnet-ip.
Paragraph (version B):
As part of the service sub-layer functions, this document describes
typical DetNet node data plane operation.  It describes the
functionality and operation of the Packet Replication (PRF), Packet
Elimination (PEF), and the Packet Ordering (POF) functions within the
service sub-layer.  Furthermore, it describes the forwarding sub-
layer.
Paragraph (version B):
As defined in RFC8655, DetNet flows may be carried over network
technologies that can provide the DetNet required service
characteristics.  For example, DetNet MPLS flows can be carried over
IEEE 802.1 Time Sensitive Network (TSN) IEEE802.1TSNTG sub-networks.
However, IEEE 802.1 TSN support is not required in DetNet.  TSN frame
preemption is an example of a forwarding layer capability that is
typically not replicated in other forwarding technologies.  Most of
DetNet benefits can be gained by running over a data link layer that
has not been specifically enhanced to support all TSN capabilities
but for certain networks and traffic mixes delay and jitter
performance may vary due to the forwarding sub-layer intrinsic
properties.
Paragraph (version B):
Different application flows, such as Ethernet or IP, can be mapped on
top of DetNet.  DetNet can optionally reuse header information
provided by, or shared with, applications.  An example of shared
header fields can be found in I-D.ietf-detnet-ip.
Paragraph (version A):
Border Gateway Protocol.
Control Word.
Paragraph (version B):
Border Gateway Protocol.
Paragraph (version A):
Label Switching Router.
Multiprotocol Label Switching.
Multiprotocol Label Switching - Traffic Engineering.
Paragraph (version B):
Border Gateway Protocol.
DetNet Control Word.
Deterministic Networking.
DetNet.
Generalized Multiprotocol Label Switching.
Generic Routing Encapsulation.
IP Security.
Layer 2.
Label Switched Path.
Multiprotocol Label Switching.
Paragraph (version A):
PseudoWire.
Quality of Service.
DetNet "service" label.
Time-Division Multiplexing.
Time-Sensitive Network.
Yet Another Next Generation.
Paragraph (version B):
Quality of Service.
DetNet "service" label.
Time-Division Multiplexing.
Time-Sensitive Network.
Yet Another Next Generation.
Paragraph (version A):
This document describes how application flows, or app-flows, are
carried over DetNet networks.  The DetNet Architecture, RFC8655,
models the DetNet related data plane functions as decomposed into two
sub-layers: a service sub-layer and a forwarding sub-layer.
Paragraph (version A):
ProtStack1 reproduced from the RFC8655,shows a logical DetNet service
with the two sub-layers.
Paragraph (version B):
This document describes how application flows, or app-flows, are
carried over DetNet networks.  The DetNet Architecture RFC8655 models
the DetNet-related data plane functions as decomposed into two sub-
layers: a service sub-layer and a forwarding sub-layer.
Paragraph (version B):
ProtStack1, reproduced from RFC8655, shows a logical DetNet service
with the two sub-layers.
Paragraph (version A):
The service sub-layer provides additional support beyond the
connectivity function of the forwarding sub-layer.  An example of
this is Packet Replication, Elimination, and Ordering functions see
PREOF.  The ordering (POF) uses sequence numbers added to packets
enabling a range of packet order protection from simple ordering and
dropping out-of-order packets to more complex reordering of a fixed
number of out-of-order, minimally delayed packets.  Reordering
requires buffer resources and has impact on the delay and jitter of
packets in the DetNet flow.
Paragraph (version B):
The service sub-layer provides additional support beyond the
connectivity function of the forwarding sub-layer.  An example of
this is Packet Replication, Elimination, and Ordering functions see
PREOF.  The ordering function (POF) uses sequence numbers added to
packets enabling a range of packet order protection from simple
ordering and dropping out-of-order packets to more complex reordering
of a fixed number of out-of-order, minimally delayed packets.
Reordering requires buffer resources and has impact on the delay and
jitter of packets in the DetNet flow.
Paragraph (version A):
The DetNet data plane is provided by the DetNet service and
forwarding sub layers.  The DetNet service sub-layer generally
provides its functions for the DetNet application flows by using or
applying existing standardized headers and/or encapsulations.  The
Detnet forwarding sub-layer may provide capabilities leveraging that
same header or encapsulation technology (e.g., DN IP or DN MPLS) or
it may be achieved by other technologies (e.g., dn_svc_encaps).
DetNet is currently defined for operation over packet switched (IP)
networks or label switched (MPLS) networks.
Paragraph (version A):
DetNet encodes specific flow attributes (flow identity and sequence
number) in packets.  For example, in DetNet IP, zero encapsulation is
used and no sequence number is available, and in DetNet MPLS, DetNet
specific information may be added explicitly to the packets in the
format of S-label and d-CW I-D.ietf-detnet-mpls .
Paragraph (version B):
The DetNet data plane is provided by the DetNet service and
forwarding sub layers.  The DetNet service sub-layer generally
provides its functions for the DetNet application flows by using or
applying existing standardized headers and/or encapsulations.  The
Detnet forwarding sub-layer may provide capabilities leveraging that
same header or encapsulation technology (e.g., DN IP or DN MPLS) or
it may be achieved by other technologies (e.g., dn_svc_encaps).
DetNet is currently defined for operation over packet-switched (IP)
networks or label-switched (MPLS) networks.
Paragraph (version B):
DetNet encodes specific flow attributes (flow identity and sequence
number) in packets.  For example, in DetNet IP, zero encapsulation is
used and no sequence number is available, and in DetNet MPLS, DetNet-
specific information may be added explicitly to the packets in the
format of S-label and d-CW I-D.ietf-detnet-mpls .
Paragraph (version A):
Metadata can be included implicit or explicit.  Explicit means that a
dedicated header field is used to include metadata in a DetNet
packet.  In case of implicit method a part of an already existing
header field is used to encode the metadata.
Paragraph (version B):
Metadata inclusion can be implicit or explicit.  Explicit inclusions
involve a dedicated header field that is used to include metadata in
a DetNet packet.  In the implicit method, part of an already existing
header field is used to encode the metadata.
Paragraph (version A):
An IP data plane may operate natively or through the use of an
encapsulation.  Many types of IP encapsulation can satisfy DetNet
requirements and it is anticipated that more than one encapsulation
may be deployed, for example GRE, IPSec etc.
Paragraph (version B):
An IP data plane may operate natively or through the use of an
encapsulation.  Many types of IP encapsulation can satisfy DetNet
requirements and it is anticipated that more than one encapsulation
may be deployed, for example GRE, IPSec.
Paragraph (version A):
In cases where metadata is needed to process an MPLS encapsulated
packet at the service sub-layer, the d-CW I-D.ietf-detnet-mpls,
RFC4385,can be used.  Although such d-CWs are frequently 32 bits
long, there is no architectural constraint on its size of this
structure, only the requirement that it is fully understood by all
parties operating on it in the DetNet service sub-layer.  The
operation of this method is described in detail in I-D.ietf-detnet-
mpls.
Paragraph (version A):
Reservation of resources can allocate resources to specific DetNet
flows.  This can eliminate packet contention and packet loss for
DetNet traffic.  This also can reduce jitter for DetNet traffic.
Resources allocated to a DetNet flow protect it from other traffic
flows.  On the other hand, DetNet flows are assumed to behave with
respect to the reserved traffic profile.  Misbehaving DetNet flows
must be able to be detected and ensure that they do not compromise
QoS of other flows.  Queuing, policing, and shaping policies can be
used to ensure that the allocation of resources reserved for DetNet
is met.
Paragraph (version A):
Use of a specific path for a flow.  This allows control of the
network delay by steering the packet with the ability to influence
the physical path.  Explicit routes complement reservation by
ensuring that a consistent path can be associated with its resources
for the duration of that path.  Coupled with the traffic mechanism,
this limits misordering and bounds latency.  Explicit route
computation can encompass a wide set of constraints and optimize the
path for a certain characteristic e.g. highest bandwidth or lowest
jitter.  In these cases the "best" path for any set of
characteristics may not be a shortest path.  The selection of path
can take into account multiple network metrics.  Some of these
metrics are measured and distributed by the routing system as traffic
engineering metrics.
Paragraph (version A):
Use of multiple packet streams using multiple paths, for example 1+1
or 1:1 linear protection.  For DetNet this primarily relates to
packet replication and elimination capabilities.  MPLS offers a
number of protection schemes.  MPLS hitless protection can be used to
switch traffic to an already established path in order to restore
delivery rapidly after a failure.  Path changes, even in the case of
failure recovery, can lead to the out of order delivery of data
requiring packet ordering functions either within the DetNet service
or at a high layer in the application traffic.  Establishment of new
paths after a failure is out of scope for DetNet services.
Paragraph (version A):
Network Coding, nwcrg not to be confused with network programming,
Paragraph (version B):
In cases where metadata is needed to process an MPLS encapsulated
packet at the service sub-layer, the d-CW I-D.ietf-detnet-mpls,
RFC4385 can be used.  Although such d-CWs are frequently 32 bits
long, there is no architectural constraint on the size of this
structure, only the requirement that it is fully understood by all
parties operating on it in the DetNet service sub-layer.  The
operation of this method is described in detail in I-D.ietf-detnet-
mpls.
Paragraph (version B):
Resources might be reserved in order to make them available for
allocation to specific DetNet flows.  This can eliminate packet
contention and packet loss for DetNet traffic.  This also can reduce
jitter for DetNet traffic.  Resources allocated to a DetNet flow
protect it from other traffic flows.  On the other hand, DetNet flows
are assumed to behave with respect to the reserved traffic profile.
It must be possible to detect misbehaving DetNet flows and to ensure
that they do not compromise QoS of other flows.  Queuing, policing,
and shaping policies can be used to ensure that the allocation of
resources reserved for DetNet is met.
Paragraph (version B):
A flow can be routed over a specific, pre-computed path.  This allows
control of the network delay by steering the packet with the ability
to influence the physical path.  Explicit routes complement
reservation by ensuring that a consistent path can be associated with
its resources for the duration of that path.  Coupled with the
traffic mechanism, this limits misordering and bounds latency.
Explicit route computation can encompass a wide set of constraints
and can optimize the path for a certain characteristic, e.g., highest
bandwidth or lowest jitter.  In these cases the "best" path for any
set of characteristics may not be a shortest path.  The selection of
path can take into account multiple network metrics.  Some of these
metrics are measured and distributed by the routing system as traffic
engineering metrics.
Paragraph (version B):
Service protection involves use of multiple packet streams using
multiple paths, for example 1+1 or 1:1 linear protection.  For
DetNet, this primarily relates to packet replication and elimination
capabilities.  MPLS offers a number of protection schemes.  MPLS
hitless protection can be used to switch traffic to an already
established path in order to restore delivery rapidly after a
failure.  Path changes, even in the case of failure recovery, can
lead to the out of order delivery of data requiring packet ordering
functions either within the DetNet service or at a high layer in the
application traffic.  Establishment of new paths after a failure is
out of scope for DetNet services.
Paragraph (version B):
Network Coding nwcrg, not to be confused with network programming,
Paragraph (version A):
traditional methods.  DetNet could utilized Network coding as an
alternative to other protection means.  Network coding is often
applied in wireless networks and is being explored for other network
types.
Paragraph (version B):
traditional methods.  DetNet could use Network coding as an
alternative to other protection means.  Network coding is often
applied in wireless networks and is being explored for other network
types.
Paragraph (version A):
The provider of a DetNet service may provide other capabilities to
monitor flows, such as more detailed loss statistics and time
stamping of events.  The details of these capabilities are currently
out of scope for this document.
Paragraph (version A):
Service protection allow DetNet services to increase reliability and
maintain a DetNet Service Assurance in the case of network congestion
or network failure.  Detnet relies on the underlying technology
capabilities for various protection schemes.  Protection schemes
enable partial or complete coverage of the network paths and active
protection with combinations of PRF, PEF, and POF.
Paragraph (version B):
The provider of a DetNet service may provide other capabilities to
monitor flows, such as more detailed loss statistics and time
stamping of events.  The details of these capabilities are out of
scope for this document.
Paragraph (version B):
Service protection allows DetNet services to increase reliability and
maintain a DetNet Service Assurance in the case of network congestion
or network failure.  Detnet relies on the underlying technology
capabilities for various protection schemes.  Protection schemes
enable partial or complete coverage of the network paths and active
protection with combinations of PRF, PEF, and POF.
Paragraph (version A):
In dn_protection_flow the numbers are used to identify the instance
of a packet.  Packet 1 is the original packet, and packets 1.1, and
second generation copy of packet 1.2 etc.  Note that these numbers
never appear in the packet, and are not to be confused with sequence
numbers, labels or any other identifier that appears in the packet.
They simply indicate the generation number of the original packet so
that its passage through the network fragment can be identified to
the reader.
Paragraph (version B):
In dn_protection_flow the numbers are used to identify the instance
of a packet.  Packet 1 is the original packet, and packets 1.1, and
second generation copy of packet 1.2, etc.  Note that these numbers
never appear in the packet, and are not to be confused with sequence
numbers, labels or any other identifier that appears in the packet.
They simply indicate the generation number of the original packet so
that its passage through the network fragment can be identified to
the reader.
Paragraph (version A):
Note that along the path from EN1 to R1 there may be zero or more
nodes which, for clarity, are not shown.  The same is true for any
other path between two DetNet entities shown in dn_protection_flow .
Paragraph (version B):
Note that along the path from EN1 to R1 there may be zero or more
nodes which, for clarity, are not shown.  The same is true for any
other path between two DetNet entities shown in dn_protection_flow.
Paragraph (version A):
This example also illustrates 1:1 protection scheme meaning there is
traffic over each segment of the end to end path.  Local DetNet relay
nodes determine which packets are eliminated and which packets are
forwarded.  A 1+1 scheme where only one path is used for traffic at a
time, could use the same topology.  In this case there is no PRF
function and traffic is switched upon detection of failure.  An OAM
scheme that monitors the paths detects the loss of path or traffic is
required to initiate the switch.  A POF may still be used in this
case to prevent misordering of packets.  In both cases the protection
paths are established and maintained for the duration of the DetNet
service.
Paragraph (version A):
In the preceding example, proper working of duplicate elimination and
reordering of packets are dependent on the number of out-of-order
packets that can be buffered and the delay difference of arriving
packets.  DetNet uses flow specific requirements (e.g., maximum
number of out-of-order packets, maximum latency of the flow, etc.)
for configuration of POF related buffers.  If the differential delay
between paths is excessively large or there is excessive mis-ordering
of the packets, then packets may be dropped instead of being
reordered.  Likewise, PEF uses the sequence number to identify
duplicate packets, and large differential delays combined with high
numbers of packets may exceed the ability of the PEF to work
properly.
Paragraph (version B):
This example also illustrates 1:1 protection scheme meaning there is
traffic over each segment of the end-to-end path.  Local DetNet relay
nodes determine which packets are eliminated and which packets are
forwarded.  A 1+1 scheme where only one path is used for traffic at a
time could use the same topology.  In this case there is no PRF
function and traffic is switched upon detection of failure.  An OAM
scheme that monitors the paths to detect the loss of path or traffic
is required to initiate the switch.  A POF may still be used in this
case to prevent misordering of packets.  In both cases the protection
paths are established and maintained for the duration of the DetNet
service.
Paragraph (version B):
In the preceding example, proper working of duplicate elimination and
reordering of packets are dependent on the number of out-of-order
packets that can be buffered and the delay difference of arriving
packets.  DetNet uses flow-specific requirements (e.g., maximum
number of out-of-order packets, maximum latency of the flow) for
configuration of POF-related buffers.  If the differential delay
between paths is excessively large or there is excessive mis-ordering
of the packets, then packets may be dropped instead of being
reordered.  Likewise, PEF uses the sequence number to identify
duplicate packets, and large differential delays combined with high
numbers of packets may exceed the ability of the PEF to work
properly.
Paragraph (version A):
Ring protection may also be supported if the underlying technology
supports it.  Many of the same concepts apply however rings are
normally 1+1 protection for data efficiency reasons.  RFC8227 is an
example of MPLS-TP data plane that supports Ring protection.
Paragraph (version A):
The DetNet data plane also allows for the aggregation of DetNet
flows, which can improve scalability by reducing the per-hop state.
How this is accomplished is data plane or control plane dependent.
When DetNet flows are aggregated, transit nodes provide service to
the aggregate and not on a per-DetNet flow basis.  When aggregating
DetNet flows the flows should be compatible i.e. the same or very
similar QoS and CoS characteristics.  In this case, nodes performing
aggregation will ensure that per-flow service requirements are
achieved.
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If bandwidth reservations are used, the sum of the reservations
should be the sum of all the individual reservations; in other words,
the reservations should not add up to an over-subscription of
bandwidth reservation.  If maximum delay bounds are used, the system
should ensure that the aggregate does not exceed the delay bounds of
the individual flows.
Paragraph (version A):
When an encapsulation is used the choice of reserving a maximum
resource level and then tracking the services in the aggregated
service or adjusting the aggregated resources as the services are
added is implementation and technology specific.
Paragraph (version B):
Ring protection may also be supported if the underlying technology
supports it.  Many of the same concepts apply, however rings are
normally 1+1 protection for data efficiency reasons.  RFC8227 is an
example of MPLS-TP data plane that supports Ring protection.
Paragraph (version B):
The DetNet data plane also allows for the aggregation of DetNet
flows, which can improve scalability by reducing the per-hop state.
How this is accomplished is data plane or control plane dependent.
When DetNet flows are aggregated, transit nodes provide service to
the aggregate and not on a per-DetNet flow basis.  When aggregating
DetNet flows, the flows should be compatible, i.e., the same or very
similar QoS and CoS characteristics.  In this case, nodes performing
aggregation will ensure that per-flow service requirements are
achieved.
Paragraph (version B):
If bandwidth reservations are used, the reservation should be the sum
of all the individual reservations; in other words, the reservations
should not add up to an over-subscription of bandwidth reservation.
If maximum delay bounds are used, the system should ensure that the
aggregate does not exceed the delay bounds of the individual flows.
Paragraph (version B):
When an encapsulation is used, the choice of reserving a maximum
resource level and then tracking the services in the aggregated
service or adjusting the aggregated resources as the services are
added is implementation and technology specific.
Paragraph (version A):
sub-network technologies.  L2 represent a generic layer-2
encapsulation that might be used on a point-to-point link.  TSN
represents the encapsulation used on an IEEE 802.1 TSN network, as
described in I-D.ietf-detnet-mpls-over-tsn.  UDP/IP represents the
encapsulation used on a DetNet IP PSN, as described in I-D.ietf-
detnet-mpls-over-udp-ip.
Paragraph (version B):
sub-network technologies.  L2 represents a generic layer-2
encapsulation that might be used on a point-to-point link.  TSN
represents the encapsulation used on an IEEE 802.1 TSN network, as
described in I-D.ietf-detnet-mpls-over-tsn.  UDP/IP represents the
encapsulation used on a DetNet IP PSN, as described in I-D.ietf-
detnet-mpls-over-udp-ip.
Paragraph (version A):
The Controller Plane corresponds to the aggregation of the Control
and Management Planes discussed in RFC7426 and RFC8655.  While more
details of any DetNet controller plane are out of the scope of this
document, there are particular considerations and requirements for
such that result from the unique characteristics of the DetNet
architecture RFC8655 and data plane as defined herein.
Paragraph (version B):
The Controller Plane corresponds to the aggregation of the Control
and Management Planes discussed in RFC7426 and RFC8655.  While more
details of any DetNet controller plane are out of the scope of this
document, there are particular considerations and requirements for
such that result from the unique characteristics of the DetNet
architecture and data plane as defined herein.
Paragraph (version A):
Each respective data plane document also covers the control plane
considerations for that technology.  For example I-D.ietf-detnet-ip
covers IP control plane normative considerations and I-D.ietf-detnet-
mpls covers MPLS control plane normative considerations.
Paragraph (version A):
Flow aggregation means that multiple App-flows are served by a single
new DetNet flow.  There are many techniques to achieve aggregation,
for example in case of IP, it can be grouping of IP flows that share
6-tuple attributes or flow identifiers at the DetNet sub-layer.
Another example includes aggregation accomplished through the use of
hierarchical LSPs in MPLS and tunnels.
Paragraph (version B):
Each respective data plane document also covers the control plane
considerations for that technology.  For example, I-D.ietf-detnet-ip
covers IP control plane normative considerations and I-D.ietf-detnet-
mpls covers MPLS control plane normative considerations.
Paragraph (version B):
Flow aggregation means that multiple app-flows are served by a single
new DetNet flow.  There are many techniques to achieve aggregation.
For example, in the case of IP, IP flows that share 6-tuple
attributes or flow identifiers at the DetNet sub-layer can be
grouped.  Another example includes aggregation accomplished through
the use of hierarchical LSPs in MPLS and tunnels.
Paragraph (version A):
When DetNet services are provisioned or requested one or more
paths meeting the requirements are selected and the resources
verified and recorded.
Paragraph (version A):
The assignment of resources along the path depends on the
technology and it includes assignment of specific links and
coordination of the queuing and other traffic management
capabilities such as policing and shaping.
Paragraph (version B):
When DetNet services are provisioned or requested, one or more
paths meeting the requirements are selected and the resources
verified and recorded.
Paragraph (version B):
The assignment of resources along the path depends on the
technology and includes assignment of specific links,
coordination of queueing, and other traffic management
capabilities such as policing and shaping.
Paragraph (version A):
Control and management mechanisms need to support bidirectional
flows, but the specification of such mechanisms are out of scope of
this document.  An example control plane solution for MPLS can be
found in RFC3473 , RFC6387 and RFC7551.  These requirements are
included in control-management-requirements.
Paragraph (version B):
Control and management mechanisms need to support bidirectional
flows, but the specification of such mechanisms are out of scope of
this document.  Example control plane solutions for MPLS can be found
in RFC3473 , RFC6387 and RFC7551.  These requirements are included in
control-management-requirements.
Paragraph (version A):
Security considerations for DetNet are described in detail in I-
D.ietf-detnet-security.  General security considerations are
described in RFC8655.  This section considers general security
considerations applicable to all data planes.
Paragraph (version A):
The primary considerations for the data plane is to maintain
integrity of data and delivery of the associated DetNet service
traversing the DetNet network.  Application flows can be protected
through whatever means is provided by the underlying technology.  For
example, encryption may be used, such as that provided by IPSec
RFC4301 for IP flows and/or by an underlying sub-net using MACSec
IEEE802.1AE-2018 for Ethernet (Layer-2) flows.
Paragraph (version B):
Security considerations for DetNet are described in detail in I-
D.ietf-detnet-security.  General security considerations for DetNet
architecture are described in RFC8655.  This section considers
general security considerations applicable to all data planes.
Paragraph (version B):
The primary consideration for the data plane is to maintain integrity
of data and delivery of the associated DetNet service traversing the
DetNet network.  Application flows can be protected through whatever
means is provided by the underlying technology.  For example,
encryption may be used, such as that provided by IPSec RFC4301 for IP
flows and/or by an underlying sub-net using MACSec IEEE802.1AE-2018
for Ethernet (Layer-2) flows.
Paragraph (version A):
To provide uninterrupted availability of the DetNet service,
provisions can be made against DOS attacks and delay attacks.  To
protect against DOS attacks, excess traffic due to malicious or
malfunctioning devices can be prevented or mitigated, for example
through the use of existing mechanism such as policing and shaping
applied at the input of a DetNet domain.  To prevent DetNet packets
from being delayed by an entity external to a DetNet domain, DetNet
technology definition can allow for the mitigation of Man-In-The-
Middle attacks, for example through use of authentication and
authorization of devices within the DetNet domain.
Paragraph (version B):
To provide uninterrupted availability of the DetNet service,
provisions can be made against DOS attacks and delay attacks.  To
protect against DOS attacks, excess traffic due to malicious or
malfunctioning devices can be prevented or mitigated, for example
through the use of existing mechanisms such as policing and shaping
applied at the input of a DetNet domain.  To prevent DetNet packets
from being delayed by an entity external to a DetNet domain, DetNet
technology definition can allow for the mitigation of Man-In-The-
Middle attacks, for example through use of authentication and
authorization of devices within the DetNet domain.