Reliable and Available Wireless Architecture
draft-ietf-raw-architecture-30
| Document | Type | Active Internet-Draft (detnet WG) | |
|---|---|---|---|
| Author | Pascal Thubert | ||
| Last updated | 2025-12-04 (Latest revision 2025-07-25) | ||
| Replaces | draft-pthubert-raw-architecture | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Informational | ||
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draft-ietf-raw-architecture-30
DetNet P. Thubert, Ed.
Internet-Draft Without Affiliation
Intended status: Informational 25 July 2025
Expires: 26 January 2026
Reliable and Available Wireless Architecture
draft-ietf-raw-architecture-30
Abstract
Reliable and Available Wireless (RAW) extends the reliability and
availability of DetNet to networks composed of any combination of
wired and wireless segments. The RAW Architecture leverages and
extends RFC 8655, the Deterministic Networking Architecture, to adapt
to challenges that affect prominently the wireless medium, notably
intermittent transmission loss. This document defines a network
control loop that optimizes the use of constrained bandwidth and
energy while assuring the expected DetNet services. The loop
involves a new Point of Local Repair (PLR) function in the DetNet
Service sub-layer that dynamically selects the DetNet path(s) for
packets to route around local connectivity degradation.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 26 January 2026.
Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
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Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. The RAW problem . . . . . . . . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1.1. ARQ . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1.2. FEC . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1.3. HARQ . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1.4. ETX . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1.5. ISM . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1.6. PER and PDR . . . . . . . . . . . . . . . . . . . . . 9
3.1.7. RSSI . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1.8. LQI . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1.9. OAM . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1.10. OODA . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1.11. SNR . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2. Link and Direction . . . . . . . . . . . . . . . . . . . 10
3.2.1. Flapping . . . . . . . . . . . . . . . . . . . . . . 11
3.2.2. Uplink . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.3. Downlink . . . . . . . . . . . . . . . . . . . . . . 11
3.2.4. Downstream . . . . . . . . . . . . . . . . . . . . . 11
3.2.5. Upstream . . . . . . . . . . . . . . . . . . . . . . 11
3.3. Path and Recovery Graphs . . . . . . . . . . . . . . . . 11
3.3.1. Path . . . . . . . . . . . . . . . . . . . . . . . . 11
3.3.2. Recovery Graph . . . . . . . . . . . . . . . . . . . 12
3.3.3. Forward and Crossing . . . . . . . . . . . . . . . . 15
3.3.4. Protection Path . . . . . . . . . . . . . . . . . . . 15
3.3.5. Segment . . . . . . . . . . . . . . . . . . . . . . . 15
3.4. Deterministic Networking . . . . . . . . . . . . . . . . 15
3.4.1. The DetNet Planes . . . . . . . . . . . . . . . . . . 15
3.4.2. Flow . . . . . . . . . . . . . . . . . . . . . . . . 16
3.4.3. Residence Time . . . . . . . . . . . . . . . . . . . 16
3.4.4. L3 Deterministic Flow Identifier . . . . . . . . . . 16
3.4.5. TSN . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.4.6. Lower-Layer API . . . . . . . . . . . . . . . . . . . 16
3.5. Reliability and Availability . . . . . . . . . . . . . . 17
3.5.1. Service Level Agreement . . . . . . . . . . . . . . . 17
3.5.2. Service Level Objective . . . . . . . . . . . . . . . 17
3.5.3. Service Level Indicator . . . . . . . . . . . . . . . 17
3.5.4. Precision Availability Metrics . . . . . . . . . . . 17
3.5.5. Reliability . . . . . . . . . . . . . . . . . . . . . 17
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3.5.6. Availability . . . . . . . . . . . . . . . . . . . . 18
4. Reliable and Available Wireless . . . . . . . . . . . . . . . 18
4.1. High Availability Engineering Principles . . . . . . . . 18
4.1.1. Elimination of Single Points of Failure . . . . . . . 18
4.1.2. Reliable Crossover . . . . . . . . . . . . . . . . . 19
4.1.3. Prompt Notification of Failures . . . . . . . . . . . 20
4.2. Applying Reliability Concepts to Networking . . . . . . . 20
4.3. Wireless Effects Affecting Reliability . . . . . . . . . 21
5. The RAW Conceptual Model . . . . . . . . . . . . . . . . . . 23
5.1. The RAW Planes . . . . . . . . . . . . . . . . . . . . . 23
5.2. RAW vs. Upper and Lower Layers . . . . . . . . . . . . . 25
5.3. RAW and DetNet . . . . . . . . . . . . . . . . . . . . . 26
6. The RAW Control Loop . . . . . . . . . . . . . . . . . . . . 30
6.1. Routing Time-Scale vs. Forwarding Time-Scale . . . . . . 31
6.2. OODA Loop . . . . . . . . . . . . . . . . . . . . . . . . 33
6.3. Observe: The RAW OAM . . . . . . . . . . . . . . . . . . 34
6.4. Orient: The RAW-extended DetNet Operational Plane . . . . 36
6.5. Decide: The Point of Local Repair . . . . . . . . . . . . 36
6.6. Act: DetNet Path Selection and Reliability Functions . . 38
7. Security Considerations . . . . . . . . . . . . . . . . . . . 39
7.1. Collocated Denial of Service Attacks . . . . . . . . . . 39
7.2. Layer-2 encryption . . . . . . . . . . . . . . . . . . . 39
7.3. Forced Access . . . . . . . . . . . . . . . . . . . . . . 40
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 40
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 40
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 40
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 41
11.1. Normative References . . . . . . . . . . . . . . . . . . 41
11.2. Informative References . . . . . . . . . . . . . . . . . 42
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 45
1. Introduction
Deterministic Networking aims at providing bounded latency and
eliminating congestion loss, even when co-existing with best-effort
traffic. It provides the ability 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].
DetNet and the related IEEE 802.1 Time-Sensitive networking (TSN)
[TSN] initially focused on wired infrastructure, which provides a
more stable communication channel than wireless networks. Wireless
networks operate on a shared medium where uncontrolled interference,
including the self-induced multipath fading, may cause intermittent
transmission losses. Fixed and mobile obstacles and reflectors may
block or alter the signal, causing transient and unpredictable
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variations of the throughput and packet delivery ratio (PDR) of a
wireless link. This adds new dimensions to the statistical effects
that affect the quality and reliability of the link.
Nevertheless, deterministic capabilities are required in a number of
wireless use cases as well [RAW-USE-CASES]. With scheduled radios
such as Time Slotted Channel Hopping (TSCH) and Orthogonal Frequency
Division Multiple Access (OFDMA) (see [RAW-TECHNOS] for more on both
of these and other technologies as well) being developed to provide
determinism over wireless links at the lower layers, providing DetNet
capabilities has become possible.
Reliable and Available Wireless (RAW) takes up the challenge of
providing highly available and reliable end-to-end performances in a
DetNet network that may include wireless segments. To achieve this,
RAW leverages all the possible transmission diversity and redundancy
to assure packet delivery, while optimizing the use of the shared
spectrum to preserve bandwidth and save energy. To that effect, RAW
defines Protection Paths can be activated dynamically upon failures
and a control loop that dynamically controls the activation and
deactivation of the feasible Protection Paths to react quickly to
intermittent losses.
The intent of RAW is to meet Service Level Objectives (SLO) in terms
of packet delivery ratio (PDR), maximum contiguous losses or latency
boundaries for DetNet flows over mixes of wired and wireless
networks, including wireless access and meshes (see Section 2 for
more on the RAW problem). This document introduces and/or leverages
terminology (see Section 3), principles (see Section 4), and concepts
such as protection path and recovery graph, to put together a
conceptual model for RAW (see Section 5), and, based on that model,
elaborate on an in-network optimization control loop (see Section 6).
2. The RAW problem
While the generic "Deterministic Networking Problem Statement"
[RFC8557] applies to both the wired and the wireless media, the
"Deterministic Networking Architecture" [DetNet-ARCHI] must be
extended to address less consistent transmissions, energy
conservation, and shared spectrum efficiency.
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Operating at Layer-3, RAW does not change the wireless technology at
the lower layers. OTOH, it can further increase diversity in the
spatial, time, code, and frequency domains by enabling multiple link-
layer wired and wireless technologies in parallel or sequentially,
for a higher resilience and a wider applicability. RAW can also
provide homogeneous services to critical applications beyond the
boundaries of a single subnetwork, e.g., using diverse radio access
technologies to optimize the end-to-end application experience.
RAW extends the DetNet services by providing elements that are
specialized for transporting IP flows over deterministic radio
technologies such as listed in [RAW-TECHNOS]. Conceptually, RAW is
agnostic to the lower layer, though the capability to control latency
is assumed to assure the DetNet services that RAW extends. How the
lower layers are operated to do so, and, e.g., whether a radio
network is single-hop or meshed, are opaque to the IP layer and not
part of the RAW abstraction. Nevertheless, cross-layer optimizations
may take place to ensure proper link awareness (think, link quality)
and packet handling (think, scheduling).
The RAW Architecture extends the DetNet Network Plane, to accommodate
one or multiple hops of homogeneous or heterogeneous wired and
wireless technologies. RAW adds reactivity to the DetNet Forwarding
sub-layer to compensate the dynamics for the radio links in terms of
lossiness and bandwidth. This may apply, for instance, to mesh
networks as illustrated in Figure 4, or diverse radio access networks
as illustrated in Figure 10.
As opposed to wired links, the availability and performance of an
individual wireless link cannot be trusted over the long term; it
varies with transient service discontinuity, and any path that
includes wireless hops is bound to face short periods of high loss.
On the other hand, being broadcast in nature, the wireless medium
provides capabilities that are atypical on modern wired links and
that the RAW Architecture can leverage opportunistically to improve
the end-to-end reliability over a collection of paths.
Those capabilities include:
Promiscuous Overhearing: Some wired and wireless technologies allow
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for multiple lower-layer attached nodes to receive the same packet
sent by another node. This differs from a lower-layer network
that is physically point-to-point like a wire. With overhearing,
more than one node in the forward direction of the packet may hear
or overhear a transmission, and the reception by one may
compensate the loss by another. The concept of path can be
revisited in favor of multipoint to multipoint progress in the
forward direction and statistical chances of successful reception
of any of the transmissions by any of the receivers.
L2-aware routing: As the quality and speed of a link varies over
time, the concept of metric must also be revisited. Shortest-path
cost loses its absolute value, and hop count turns into a bad idea
as the link budget drops with the physical distance. Routing over
radio requires both 1) a new and more dynamic sense of link
metrics, with new protocols such as DLEP and L2-trigger to keep L3
up to date with the link quality and availability, and 2) an
approach to multipath routing, where multiple link metrics are
considered since simple shortest-path cost loses its meaning with
the instability of the metrics.
Redundant transmissions: Though feasible on any technology,
proactive (forward) and reactive (ack-based) error correction are
typical to the wireless media. Bounded latency can still be
obtained on a wireless link while operating those technologies,
provided that link latency used in path selection allows for the
extra transmission, or that the introduced delay is compensated
along the path. In the case of coded fragments and retries, it
makes sense to vary all the possible physical properties of the
transmission to reduce the chances that the same effect causes the
loss of both original and redundant transmissions.
Relay Coordination and constructive interference: Though it can be
difficult to achieve at high speed, a fine time synchronization
and a precise sense of phase allows the energy from multiple
coordinated senders to add up at the receiver and actually improve
the signal quality, compensating for either distance or physical
objects in the Fresnel zone that would reduce the link budget.
From a DetNet perspective, this may translate taking into account
how transmission from one node may interfere with the transmission
of another node attached to the same wireless sub-layer network.
RAW and DetNet enable application flows that require a special
treatment along paths that can provide that treatment. This may be
seen as a form of Path Aware Networking and may be subject to
impediments documented in [RFC9049].
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The mechanisms used to establish a path is not unique to, or
necessarily impacted by, RAW. It is expected to be the product of
the DetNet Controller Plane
[I-D.ietf-detnet-controller-plane-framework], and may use a Path
computation Element (PCE) [RFC4655] or the DetNet Yang Data Model
[RFC9633], or may be computed in a distributed fashion ala Resource
ReSerVation Protocol (RSVP) [RFC2205]. Either way, the assumption is
that it is slow relative to local forwarding operations along the
path. To react fast enough to transient changes in the radio
transmissions, RAW leverages DetNet Network Plane enhancements to
optimize the use of the paths and match the quality of the
transmissions over time.
As opposed to wired networks, the action of installing a path over a
set of wireless links may be very slow relative to the speed at which
the radio conditions vary, and it makes sense in the wireless case to
provide redundant forwarding solutions along a alternate paths (see
Section 3.3) and to leave it to the Network Plane to select which of
those forwarding solutions are to be used for a given packet based on
the current conditions. The RAW Network Plane operations happen
within the scope of a recovery graph (see Section 3.3.2) that is pre-
established and installed by means outside of the scope of RAW. A
recovery graph may be strict or loose depending on whether each or
just a subset of the hops are observed and controlled by RAW.
RAW distinguishes the longer time-scale at which routes are computed
from the shorter time-scale where forwarding decisions are made (see
Section 6.1). The RAW Network Plane operations happen at a time-
scale that sits timewise between the routing and the forwarding time-
scales. Their goal is to select dynamically, within the resources
delineated by a recovery graph, the protection path(s) that the
upcoming packets of a DetNet flow shall follow. As they influence
the path for entire or portion of flows, the RAW Network Plane
operations may affect the metrics used in their rerouting decision,
which could potentially lead to oscillations; such effects must be
avoided or dampened.
3. Terminology
RAW reuses terminology defined for DetNet in the "Deterministic
Networking Architecture" [DetNet-ARCHI], e.g., PREOF for Packet
Replication, Elimination and Ordering Functions. RAW inherits and
augments the IETF art of Protection as seen in DetNet and Traffic
Engineering.
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RAW reuses terminology defined for Operations, Administration, and
Maintenance (OAM) protocols in Section 1.1 of the "Framework of OAM
for DetNet" [DetNet-OAM] and "Active and Passive Metrics and Methods
(with Hybrid Types In-Between)" [RFC7799].
RAW also reuses terminology defined for MPLS in [RFC4427] such as the
term recovery as covering both Protection and Restoration, a number
of recovery types. That document defines a number of concepts such
as recovery domain that are used in the RAW mechanisms, and defines
the new term recovery graph. A recovery graph associates a
topological graph with usage metadata that represents how the paths
are built and used within the recovery graph. The recovery graph
provides excess bandwidth for the intended traffic over alternate
potential paths, and the use of that bandwidth is optimized
dynamically.
RAW also reuses terminology defined for RSVP-TE in [RFC4090] such as
the Point of Local Repair (PLR). The concept of backup path is
generalized with protection path, which is the term mostly found in
recent standards and used in this document.
RAW also reuses terminology defined for 6TiSCH in [6TiSCH-ARCHI] and
equates the 6TiSCH concept of a Track with that of a recovery graph.
The concept of recovery graph is agnostic to the underlying
technology and applies but is not limited to any full or partial
wireless mesh. RAW specifies strict and loose recovery graphs
depending on whether the path is fully controlled by RAW or traverses
an opaque network where RAW cannot observe and control the individual
hops.
RAW uses the following terminology and acronyms:
3.1. Acronyms
3.1.1. ARQ
Automatic Repeat Request, a well-known mechanism, enabling an
acknowledged transmission with retries to mitigate errors and loss.
ARQ may be implemented at various layers in a network. ARQ is
typically implemented at Layer-2, per hop and not end-to-end in
wireless networks. ARQ improves delivery on lossy wireless.
Additionally, ARQ retransmission may be further limited by a bounded
time to meet end-to-end packet latency constraints. Additional
details and considerations for ARQ are detailed in [RFC3366].
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3.1.2. FEC
Forward Error Correction, adding redundant data to protect against a
partial loss without retries.
3.1.3. HARQ
Hybrid ARQ, combining FEC and ARQ.
3.1.4. ETX
Expected Transmission Count: a statistical metric that represents the
expected total number of packet transmissions (including
retransmissions) required to successfully deliver a packet along a
path, used by 6TiSCH [RFC6551].
3.1.5. ISM
The industrial, scientific, and medical (ISM) radio band refers to a
group of radio bands or parts of the radio spectrum (e.g., 2.4 GHz
and 5 GHz) that are internationally reserved for the use of radio
frequency (RF) energy intended for scientific, medical, and
industrial requirements, e.g., by microwaves, depth radars, and
medical diathermy machines. Cordless phones, Bluetooth and LoWPAN
devices, near-field communication (NFC) devices, garage door openers,
baby monitors, and Wi-Fi networks may all use the ISM frequencies,
although these low-power transmitters are not considered to be ISM
devices. In general, communications equipment operating in ISM bands
must tolerate any interference generated by ISM applications, and
users have no regulatory protection from ISM device operation in
these bands.
3.1.6. PER and PDR
The Packet Error Rate (PER) is defined as the ratio of the number of
packets received in error to the total number of transmitted packets.
A packet is considered to be in error if even a single bit within the
packet is received incorrectly. In contrast, the Packet Delivery
Ratio (PDR) indicates the ratio of the number successful delivery of
data packets to the total number of transmitted packets from the
sender to the receiver.
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3.1.7. RSSI
Received Signal Strength Indication (a.k.a. Energy Detection Level):
a measure of incoherent (raw) RF power in a channel. The RF power
can come from any source: other transmitters using the same
technology, other radio technology using the same band, or background
radiation. For a single-hop, RSSI may be used for LQI.
3.1.8. LQI
The link quality indicator (LQI) is an indication of the quality of
the data packets received by the receiver. It is typically derived
from packet error statistics, the exact method depending on the
network stack being used. LQI values may be exposed to the
controller plane for each individual hop or cumulated along segments.
Outgoing LQI values can be calculated from coherent (demodulated)
PER, RSSI and incoming LQI values.
3.1.9. OAM
OAM stands for Operations, Administration, and Maintenance, and
covers the processes, activities, tools, and standards involved with
operating, administering, managing, and maintaining any system. This
document uses the terms Operations, Administration, and Maintenance,
in conformance with the 'Guidelines for the Use of the "OAM" Acronym
in the IETF' [RFC6291] and the system observed by the RAW OAM is the
recovery graph.
3.1.10. OODA
OODA (Observe, Orient, Decide, Act) is a generic formalism to
represent the operational steps in a Control Loop. In the context of
RAW, OODA is applied to network control and convergence, more in
Section 6.2.
3.1.11. SNR
Signal-Noise Ratio (a.k.a. S/N): a measure used in science and
engineering that compares the level of a desired signal to the level
of background noise. SNR is defined as the ratio of signal power to
noise power, often expressed in decibels.
3.2. Link and Direction
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3.2.1. Flapping
In the context of RAW, a link flaps when the reliability of the
wireless connectivity drops abruptly for a short period of time,
typically of a subsecond to seconds duration.
3.2.2. Uplink
Connection from end-devices to data communication equipment. In the
context of wireless, uplink refers to the connection between a
station (STA) and a controller (AP) or a User Equipment (UE) to a
Base Station (BS) such as a 3GPP 5G gNodeB (gNb).
3.2.3. Downlink
The reverse direction from uplink.
3.2.4. Downstream
Following the direction of the flow data path along a recovery graph.
3.2.5. Upstream
Against the direction of the flow data path along a recovery graph.
3.3. Path and Recovery Graphs
3.3.1. Path
Quoting section 1.1.3 of [INT-ARCHI]:
| At a given moment, all the IP datagrams from a particular source
| host to a particular destination host typically traverse the same
| sequence of gateways. We use the term "path" for this sequence.
| Note that a path is unidirectional; it is not unusual to have
| different paths in the two directions between a given host pair.
Section 2 of [RFC9473] points to a longer, more modern definition of
path, which begins as follows:
| A sequence of adjacent path elements over which a packet can be
| transmitted, starting and ending with a node.
|
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| Paths are unidirectional and time-dependent, i.e., there can be a
| variety of paths from one node to another, and the path over which
| packets are transmitted may change. A path definition can be
| fixed (i.e., the exact sequence of path elements remains the same)
| or mutable (i.e., the start and end node remain the same, but the
| path elements between them may vary over time).
|
| The representation of a path and its properties may depend on the
| entity considering the path. On the one hand, the representation
| may differ due to entities having partial visibility of path
| elements comprising a path or their visibility changing over time.
It follows that the general acceptance of a path is a linear sequence
of links and nodes, as opposed to a multi-dimensional graph, defined
by the experience of the packet that went from a node A to a node B.
In the context of this document, a path is observed by following one
copy or one fragment of a packet that conserves its uniqueness and
integrity. For instance, if C replicates to E and F and D eliminates
duplicates, a packet from A to B can experience 2 paths,
A->C->E->D->B and A->C->F->D->B. Those paths are called protection
paths. Protection paths may be fully non-congruent, and
alternatively may intersect at replication or elimination points.
With DetNet and RAW, a packet may be duplicated, fragmented, and
network-coded, and the various byproducts may travel different paths
that are not necessarily end-to-end between A and B; we refer to that
complex scenario as a DetNet path. As such, the DetNet path extends
the above description of a path, but it still matches the experience
of a packet that traverses the network.
With RAW, the path experienced by a packet is subject to change from
one packet to the next, but all the possible experiences are all
contained within a finite set. Therefore, we introduce below the
term of a recovery graph that coalesces that set and covers the
overall topology where the possible DetNet paths are all contained.
As such, the recovery graph coalesces all the possible paths a flow
may experience, each with its own statistical probability to be used.
3.3.2. Recovery Graph
A networking graph that can be followed to transport packets with
equivalent treatment, associated with usage metadata; as opposed to
the definition of a path above, a recovery graph represents not an
actual but a potential, it is not necessarily a linear sequence like
a simple path, and is not necessarily fully traversed (flooded) by
all packets of a flow like a DetNet Path. Still, and as a
simplification, the casual reader may consider that a recovery graph
is very much like a DetNet path, aggregating multiple paths that may
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overlap, fork and rejoin, for instance to enable a protection service
by the PREOF operations.
_________
| |
| IoT G/W |
|_________|
EGRESS <<=== Elimination at Egress
| |
---+--------+--+--------+--------
| Backbone |
__|__ __|__
| | Backbone | | Backbone
|__ __| Router |__ __| Router
| # |
# \ # / <-- protection path
# # #-------#
\ # / # ( Low-power )
# # \ / # ( Lossy Network)
\ /
# INGRESS <<=== Replication at recovery graph Ingress
|
# <-- source device
#: Low-power device
Figure 1: Example IoT Recovery Graph to an IoT Gateway with 1+1
Redundancy
Refining further, a recovery graph is defined as the coalescence of
the collection of all the feasible DetNet Paths that a packet for
which a flow is assigned to the recovery graph may be forwarded
along. A packet that is assigned to the recovery graph experiences
one of the feasible DetNet Paths based on the current selection by
the PLR at the time the packet traverses the network.
Refining even further, the feasible DetNet Paths within the recovery
graph may or may not be computed in advance, but decided upon the
detection of a change from a clean slate. Furthermore, the PLR
decision may be distributed, which yields a large combination of
possible and dependent decisions, with no node in the network capable
of reporting which is the current DetNet Path within the recovery
graph.
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In DetNet [DetNet-ARCHI] terms, a recovery graph has the following
properties:
* A recovery graph is a Layer-3 abstraction built upon IP links
between routers. A router may form multiple IP links over a
single radio interface.
* A recovery graph has one Ingress and one Egress node, which
operate as DetNet Edge nodes.
* The graph of a recovery graph is reversible, meaning that packets
can be routed against the flow of data packets, e.g., to carry OAM
measurements or control messages back to the Ingress.
* The vertices of that graph are DetNet Relay Nodes that operate at
the DetNet Service sub-layer and provide the PREOF functions.
* The topological edges of the graph are strict sequences of DetNet
Transit nodes that operate at the DetNet Forwarding sub-layer.
Figure 2 illustrates the generic concept of a recovery graph, between
an Ingress Node and an Egress Node. The recovery graph is composed
of forward protection paths and forward or crossing Segments (see the
definition for those terms in the next sections). The recovery graph
contains at least 2 protection paths as a main path and a backup
path.
------------------- forward direction ---------------------->
a ==> b ==> C -=- F ==> G ==> h T1 I: Ingress
/ \ / | \ / E: Egress
I o n E -=- T2 T1, T2, T3:
\ / \ | / \ External
p ==> q ==> R -=- T ==> U ==> v T3 Targets
Uppercase: DetNet Relay Nodes
Lowercase: DetNet Transit nodes
I ==> a ==> b ==> C : A forward Segment to targets F and o
C ==> o ==> T: A forward Segment to target T (and/or U)
G | n | U : A crossing Segment to targets G or U
I -> F -> E : A forward Protection Path to targets T1, T2, and T3
I, a, b, C, F, G, h, E : a path to T1, T2, and/or T3
I, p, q, R, o, F, G, h, E : segment-crossing protection path
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Figure 2: A Recovery Graph and its Components
3.3.3. Forward and Crossing
Forward refers to progress towards the recovery graph Egress.
Forward links are directional, and packets that are forwarded along
the recovery graph can only be transmitted along the link direction.
Crossing links are bidirectional, meaning that they can be used in
both directions, though a given packet may use the link in one
direction only. A Segment can be forward, in which case it is
composed of forward links only, or crossing, in which case it is
composed of crossing links only. A Protection Path is always
forward, meaning that it is composed of forward links and Segments.
3.3.4. Protection Path
An end-to-end forward path between the Ingress and Egress Nodes of a
recovery graph. A protection path in a recovery graph is expressed
as a strict sequence of DetNet Relay Nodes or as a loose sequence of
DetNet Relay Nodes that are joined by recovery graph Segments.
Background information on the concepts related to protection paths
can be found in [RFC4427] and [RFC6378]
3.3.5. Segment
A strict sequence of DetNet Transit nodes between 2 DetNet Relay
Nodes; a Segment of a recovery graph is composed topologically of two
vertices of the recovery graph and one edge of the recovery graph
between those vertices.
3.4. Deterministic Networking
This document reuses the terminology in section 2 of [RFC8557] and
section 4.1.2 of [DetNet-ARCHI] for deterministic networking and
deterministic networks.
3.4.1. The DetNet Planes
[DetNet-ARCHI] defines three planes: the Application (User) Plane,
the Controller Plane, and the Network Plane. The DetNet Network
Plane is composed of a Data Plane (packet forwarding) and an
Operational Plane where OAM operations take place. In the Network
Plane, the DetNet Service sub-layer focuses on flow protection (e.g.,
using redundancy) and can be fully operated at Layer-3, while the
DetNet forwarding sub-layer establishes the paths, associates the
flows to the paths, and ensures the availability of the necessary
resources, leverages Layer-2 functionalities for timely delivery to
the next DetNet system, more in Section 2.
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3.4.2. Flow
A collection of consecutive IP packets defined by the upper layers
and signaled by the same 5 or 6-tuple (see section 5.1 of [RFC8939]).
Packets of the same flow must be placed on the same recovery graph to
receive an equivalent treatment from Ingress to Egress within the
recovery graph. Multiple flows may be transported along the same
recovery graph. The DetNet Path that is selected for the flow may
change over time under the control of the PLR.
3.4.3. Residence Time
A residence time (RT) is defined as the time interval between when
the reception of a packet starts and the transmission of the packet
begins. In the context of RAW, RT is useful for a transit node, not
ingress or egress.
3.4.4. L3 Deterministic Flow Identifier
See section 3.3 of [DetNet-DP]. The classic IP 5-tuple that
identifies a flow comprises the source IP, destination IP, source
port, destination port, and the upper layer protocol (ULP). DetNet
uses a 6-tuple where the extra field is the DSCP field in the packet.
The IPv6 flow label is not used for that purpose.
3.4.5. TSN
TSN stands for Time-Sensitive Networking and denotes the efforts at
IEEE 802 for deterministic networking, originally for use on
Ethernet. Wireless TSN (WTSN) denotes extensions of the TSN work on
wireless media such as the selected RAW technologies [RAW-TECHNOS].
3.4.6. Lower-Layer API
In addition, RAW includes the concept of a lower-layer API (LL API),
that provides an interface between the lower layer (e.g., wireless)
technology and the DetNet layers. The LL API is technology dependent
as what the lower layers expose towards the DetNet layers may vary.
Furthermore, the different RAW technologies are equipped with
different reliability features, e.g., short range broadcast,
Multiple-User, Multiple-Input, and Multiple-Output (MUMIMO), PHY rate
and other Modulation Coding Scheme (MCS) adaptation, coding and
retransmissions methods, constructive interference and overhearing,
see [RAW-TECHNOS] for details. The LL API enables interactions
between the reliability functions provided by the lower layer and the
reliability functions provided by DetNet. That is, the LL API makes
cross-layer optimization possible for the reliability functions of
different layers depending on the actual exposure provided via the LL
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API by the given RAW technology. The Dynamic Link Exchange Protocol
(DLEP) [DLEP] is an example protocol that can be used to implement
the LL API.
3.5. Reliability and Availability
In the context of the RAW work, Reliability and Availability are
defined as follows:
3.5.1. Service Level Agreement
In the context of RAW, an SLA (service level agreement) is a contract
between a provider (the network) and a client, the application flow,
defining measurable metrics such as latency boundaries, consecutive
losses, and packet delivery ratio (PDR).
3.5.2. Service Level Objective
A service level objective (SLO) is one term in the SLA, for which
specific network setting and operations are implemented. For
instance, a dynamic tuning of the packet redundancy addresses an SLO
of consecutive losses in a row by augmenting the chances of delivery
of a packet that follows a loss.
3.5.3. Service Level Indicator
A service level indicator (SLI) measures the compliance of an SLO to
the terms of the contract. It can be for instance, the statistics of
individual losses and losses in a row as time series.
3.5.4. Precision Availability Metrics
Precision Availability Metrics (PAMs) [RFC9544] aim at capturing
service levels for a flow, specifically the degree to which the flow
complies with the SLOs that are in effect.
3.5.5. Reliability
Reliability is a measure of the probability that an item (e.g.,
system, network) will perform its intended function with no failure
for a stated period of time (or a stated number of demands or load)
under stated environmental conditions. In other words, reliability
is the probability that an item will be in an uptime state (i.e.,
fully operational or ready to perform) for a stated mission, e.g., to
provide an SLA. See more in [NASA1].
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3.5.6. Availability
Availability is the probability of an item’s (e.g., a network’s)
mission readiness (e.g., to provide an SLA), an uptime state with the
likelihood of a recoverable downtime state. Availability is
expressed as (uptime)/(uptime+downtime). Note that it is
availability that addresses downtime (including time for maintenance,
repair, and replacement activities) and not reliability. See more in
[NASA2].
4. Reliable and Available Wireless
4.1. High Availability Engineering Principles
The reliability criteria of a critical system pervade through its
elements, and if the system comprises a data network and then the
data network is also subject to the inherited reliability and
availability criteria. It is only natural to consider the art of
high availability engineering and apply it to wireless communications
in the context of RAW.
There are three principles (pillars) of high availability
engineering:
1. elimination of each single point of failure
2. reliable crossover
3. prompt detection of failures as they occur
These principles are common to all high availability systems, not
just ones with Internet technology at the center. Examples of both
non-Internet and Internet are included.
4.1.1. Elimination of Single Points of Failure
Physical and logical components in a system happen to fail, either as
the effect of wear and tear, when used beyond acceptable limits, or
due to a software bug. It is necessary to decouple component failure
from system failure to avoid the latter. This allows failed
components to be restored while the rest of the system continues to
function.
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IP Routers leverage routing protocols to reroute to alternate routes
in case of a failure. When links are cabled through the same
conduit, they form a shared risk link group (SRLG), and share the
same fate if the conduit is cut, making the reroute operation
ineffective. The same effect can happen with virtual links that end
up in a same physical transport through the intricacies of nested
encapsulation. In a same fashion, an interferer or an obstacle may
affect multiple wireless transmissions at the same time, even between
different sets of peers.
Intermediate network Nodes such as routers, switches and APs, wire
bundles, and the air medium itself can become single points of
failure. For High Availability, it is thus required to use
physically link-disjoint and Node-disjoint paths; in the wireless
space, it is also required to use the highest possible degree of
diversity (time, space, code, frequency, channel width) in the
transmissions over the air to combat the additional causes of
transmission loss.
From an economics standpoint, executing this principle properly
generally increases capital expense because of the redundant
equipment. In a constrained network where the waste of energy and
bandwidth should be minimized, an excessive use of redundant links
must be avoided; for RAW this means that the extra bandwidth must be
used wisely and efficiently.
4.1.2. Reliable Crossover
Having backup equipment has a limited value unless it can be reliably
switched into use within the down-time parameters. IP Routers
execute reliable crossover continuously because the routers use any
alternate routes that are available [RFC0791]. This is due to the
stateless nature of IP datagrams and the dissociation of the
datagrams from the forwarding routes they take. The "IP Fast Reroute
Framework" [FRR] analyzes mechanisms for fast failure detection and
path repair for IP Fast-Reroute (FRR), and discusses the case of
multiple failures and SRLG. Examples of FRR techniques include
Remote Loop-Free Alternate [RLFA-FRR] and backup label-switched path
(LSP) tunnels for the local repair of LSP tunnels using RSVP-TE
[RFC4090].
Deterministic flows, on the contrary, are attached to specific paths
where dedicated resources are reserved for each flow. Therefore,
each DetNet path must inherently provide sufficient redundancy to
provide the assured SLOs at all times. The DetNet PREOF typically
leverages 1+1 redundancy whereby a packet is sent twice, over non-
congruent paths. This avoids the gap during the fast reroute
operation, but doubles the traffic in the network.
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In the case of RAW, the expectation is that multiple transient faults
may happen in overlapping time windows, in which case the 1+1
redundancy with delayed reestablishment of the second path does not
provide the required guarantees. The Data Plane must be configured
with a sufficient degree of redundancy to select an alternate
redundant path immediately upon a fault, without the need for a slow
intervention from the Controller Plane.
4.1.3. Prompt Notification of Failures
The execution of the two above principles is likely to render a
system where the end user rarely sees a failure. But a failure that
occurs must still be detected in order to direct maintenance.
There are many reasons for system monitoring (FCAPS for fault,
configuration, accounting, performance, security is a handy mental
checklist) but fault monitoring is sufficient reason.
"Overview and Principles of Internet Traffic Engineering" [TE]
discusses the importance of measurement for network protection, and
provides an abstract method for network survivability with the
analysis of a traffic matrix as observed via a network management
YANG data model, probing techniques, file transfers, IGP link state
advertisements, and more.
Those measurements are needed in the context of RAW to inform the
controller and make the long-term reactive decision to rebuild a
recovery graph based on statistical and aggregated information. RAW
itself operates in the DetNet Network Plane at a faster time-scale
with live information on speed, state, etc. This live information
can be obtained directly from the lower layer, e.g., using L2
triggers, read from a protocol such as DLEP, or transported over
multiple hops using OAM and reverse OAM, as illustrated in Figure 11.
4.2. Applying Reliability Concepts to Networking
The terms Reliability and Availability are defined for use in RAW in
Section 3 and the reader is invited to read [NASA1] and [NASA2] for
more details on the general definition of Reliability. Practically
speaking, a number of nines is often used to indicate the reliability
of a data link, e.g., 5 nines indicate a Packet Delivery Ratio (PDR)
of 99.999%.
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This number is typical in a wired environment where the loss is due
to a random event such as a solar particle that affects the
transmission of a particular packet, but does not affect the previous
or next packet, nor packets transmitted on other links. Note that
the QoS requirements in RAW may include a bounded latency, and a
packet that arrives too late is a fault and not considered as
delivered.
For a periodic networking pattern such as an automation control loop,
this number is proportional to the Mean Time Between Failures (MTBF).
When a single fault can have dramatic consequences, the MTBF
expresses the chances that the unwanted fault event occurs. In data
networks, this is rarely the case. Packet loss cannot be fully
avoided and the systems are built to resist some loss, e.g., using
redundancy with Retries (as in HARQ), Packet Replication and
Elimination (PRE) FEC, Network Coding (e.g., using FEC with SCHC
[RFC8724] fragments), or, in a typical control loop, by linear
interpolation from the previous measurements.
But the linear interpolation method cannot resist multiple
consecutive losses, and a high MTBF is desired as a guarantee that
this does not happen, in other words that the number of losses-in-
a-row can be bounded. In that case, what is really desired is a
Maximum Consecutive Loss (MCL). (See also section 5.9.5 in [DLEP].)
If the number of losses in a row passes the MCL, the control loop has
to abort and the system, e.g., the production line, may need to enter
an emergency stop condition.
Engineers that build automated processes may use the network
reliability expressed in nines as an MTBF as a proxy to indicate an
MCL, e.g., as described in section 7.4 of the "Deterministic
Networking Use Cases" [RFC8578].
4.3. Wireless Effects Affecting Reliability
In contrast with wired networks, errors in transmission are the
predominant source of packet loss in wireless networks.
The root cause for the loss may be of multiple origins, calling for
the use of different forms of diversity:
Multipath Fading: A destructive interference by a reflection of the
original signal.
A radio signal may be received directly (line-of-sight) and/or as
a reflection on a physical structure (echo). The reflections take
a longer path and are delayed by the extra distance divided by the
speed of light in the medium. Depending on the frequency, the
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echo lands with a different phase which may add up to
(constructive interference) or cancel (destructive interference)
the direct signal.
The affected frequencies depend on the relative position of the
sender, the receiver, and all the reflecting objects in the
environment. A given hop suffers from multipath fading for
multiple packets in a row till a physical movement changes the
reflection patterns.
Co-channel Interference: Energy in the spectrum used for the
transmission confuses the receiver.
The wireless medium itself is a Shared Risk Link Group (SRLG) for
nearby users of the same spectrum, as an interference may affect
multiple co-channel transmissions between different peers within
the interference domain of the interferer, possibly even when they
use different technologies.
Obstacle in Fresnel Zone: The Fresnel zone is an elliptical region
of space between and around the transmit and receive antennas in a
point-to-point wireless communication. The optimal transmission
happens when it is free of obstacles.
In an environment that is rich in metallic structures and mobile
objects, a single radio link provides a fuzzy service, meaning that
it cannot be trusted to transport the traffic reliably over a long
period of time.
Transmission losses are typically not independent, and their nature
and duration are unpredictable; as long as a physical object (e.g., a
metallic trolley between peers) that affects the transmission is not
removed, or as long as the interferer (e.g., a radar in the ISM band)
keeps transmitting, a continuous stream of packets are affected.
The key technique to combat those unpredictable losses is diversity.
Different forms of diversity are necessary to combat different causes
of loss and the use of diversity must be maximized to optimize the
PDR.
A single packet may be sent at different times (time diversity) over
diverse paths (spatial diversity) that rely on diverse radio channels
(frequency diversity) and diverse PHY technologies, e.g., narrowband
vs. spread spectrum, or diverse codes. Using time diversity defeats
short-term interferences; spatial diversity combats very local causes
of interference such as multipath fading; narrowband and spread
spectrum are relatively innocuous to one another and can be used for
diversity in the presence of the other.
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5. The RAW Conceptual Model
RAW extends the conceptual model described in section 4 of the DetNet
Architecture [DetNet-ARCHI] with the PLR at the Service sub-layer, as
illustrated in Figure 3. The PLR (see Section 6.5) is a point of
local reaction to provide additional agility against transmission
loss. The PLR can act, e.g., based on indications from the lower
layer or based on OAM.
| packets going | ^ packets coming ^
v down the stack v | up the stack |
+-----------------------+ +-----------------------+
| Source | | Destination |
+-----------------------+ +-----------------------+
| Service sub-layer: | | Service sub-layer: |
| Packet sequencing | | Duplicate elimination |
| Flow replication | | Flow merging |
| Packet encoding | | Packet decoding |
| Point of Local Repair | | |
+-----------------------+ +-----------------------+
| Forwarding sub-layer: | | Forwarding sub-layer: |
| Resource allocation | | Resource allocation |
| Explicit routes | | Explicit routes |
+-----------------------+ +-----------------------+
| Lower layers | | Lower layers |
+-----------------------+ +-----------------------+
v ^
\_________________________/
Figure 3: Extended DetNet Data-Plane Protocol Stack
5.1. The RAW Planes
The RAW Nodes are DetNet Relay Nodes that operate in the RAW Network
Plane and are capable of additional diversity mechanisms and
measurement functions related to the radio interface. RAW leverages
an Operational Plane orientation function (that typically operates
inside the Ingress Edge Nodes) to dynamically adapt the path of the
packets and optimizes the resource usage.
In the case of centralized routing operations, the RAW Controller
Plane Function (CPF) interacts with RAW Nodes over a Southbound API.
It consumes data and information from the network and generates
knowledge and wisdom to help steer the traffic optimally inside a
recovery graph.
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DetNet Routing
CPF CPF CPF CPF
Southbound API
_-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-
_-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-
___ RAW ___ RAW ___ RAW ___ RAW __
/ Node Node Node Node \
Ingress __/ / \ / \ \____Egress
End __ / \ / .- -- . \ ___ End
Node \ / \ / .-( ). \ / Node
\_ RAW ___ RAW ___(Non-RAW Nodes)__ RAW _/
Node Node (___.______.____) Node
Figure 4: RAW Nodes (Centralized Routing Case)
When a new flow is defined, the routing function uses its current
knowledge of the network to build a new recovery graph between an
Ingress End System and an Egress End System for that flow; it
indicates to the RAW Nodes where the PREOF and/or radio diversity and
reliability operations may be actioned in the Network Plane.
* The recovery graph may be strict, meaning that the DetNet
forwarding sub-layer operations are enforced end-to-end
* The recovery graph may be expressed loosely to enable traversing a
non-RAW subnetwork as in Figure 7. In that case, RAW cannot
leverage end-to-end DetNet and cannot provide latency guarantees.
The information that the orientation function reports to the routing
function includes may be a time-aggregated, e.g., statistical
fashion, to match the longer-term operation of the routing function.
Example information includes Link-Layer metrics such as Link
bandwidth (the medium speed depends dynamically on the mode of the
physical (PHY) layer), number of flows (bandwidth that can be
reserved for a flow depends on the number and size of flows sharing
the spectrum) and average and mean squared deviation of availability
and reliability metrics, such as Packet Delivery Ratio (PDR) over
long periods of time. It may also report an aggregated expected
transmission count (ETX), or a variation of it.
Based on those metrics, the routing function installs the recovery
graph with enough redundant forwarding solutions to ensure that the
Network Plane can reliably deliver the packets within an SLA
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associated with the flows that it transports. The SLA defines end-
to-end reliability and availability requirements, in which
reliability may be expressed as a successful delivery in-order and
within a bounded delay of at least one copy of a packet.
Depending on the use case and the SLA, the recovery graph may
comprise non-RAW segments, either interleaved inside the recovery
graph (e.g. over tunnels), or all the way to the Egress End Node
(e.g., a server in the local wired domain). RAW observes the Lower-
Layer Links between RAW nodes (typically, radio links) and the end-
to-end Network Layer operation to decide at all times which of the
diversity schemes is actioned by which RAW Nodes.
Once a recovery graph is established, per-segment and end-to-end
reliability and availability statistics are periodically reported to
the routing function to ensure that the SLA can be met or if not,
then have the recovery graph recomputed.
5.2. RAW vs. Upper and Lower Layers
RAW builds on DetNet-provided features such as scheduling and
shaping. In particular, RAW inherits the DetNet guarantees on end-
to-end latency, which can be tuned to ensure that DetNet and RAW
reliability mechanisms have no side effect on upper layers, e.g., on
transport-layer packet recovery. RAW operations include possible
rerouting, which in turn may affect the ordering of a burst of
packets. RAW also inherits PREOF from DetNet, which can be used to
reorder packets before delivery to the upper layers. As a result,
DetNet in general and RAW in particular offer a smoother transport
experience for the upper layers than the Internet at large with
ultra-low jitter and loss.
RAW improves the reliability of transmissions and the availability of
the communication resources, and should be seen as a dynamic
optimization of the use of redundancy to maintain it within certain
boundaries. For instance, ARQ, which provides 1-hop reliability
through acknowledgements and retries, and FEC codes such as turbo
codes which reduce the PER, are typically operated at Layer-2 and
Layer-1 respectively. In both cases, redundant transmissions improve
the 1-hop reliability at the expense of energy and latency, which are
the resources that RAW must control. In order to achieve its goals,
RAW may leverage the lower-layer operations by abstracting the
concept and providing hints to the lower layers on the desired
outcome, e.g., in terms of reliability and timeliness, as opposed to
performing the actual operations at Layer-3.
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Guarantees such as bounded latency depend on the upper layers
(Transport or Application) to provide the payload in volumes and at
times that match the contract with the DetNet sub-layers and the
layers below. Excess of incoming traffic at the DetNet Ingress may
result in dropping or queueing of packets, and can entail loss,
latency, or jitter, and therefore, violate the guarantees that are
provided inside the DetNet Network.
When the traffic from upper layers matches the expectation of the
lower layers, RAW still depends on DetNet mechanisms and the lower
layers to provide the timing and physical resource guarantees that
are needed to match the traffic SLA. When the availability of the
physical resource varies, RAW acts on the distribution of the traffic
to leverage alternates within a finite set of potential resources.
The Operational Plane elements (Routing and OAM control) may gather
aggregated information from lower layers about e.g., link quality,
either via measurement or communication with the lower layer. This
information may be obtained from inside the device using specialized
APIs (e.g., L2 triggers), via monitoring and measurement protocols
such as BFD [RFC5880] and STAMP [RFC8762], respectively, or via a
control protocol exchange with the lower layer via, e.g., DLEP
[DLEP]. It may then be processed and exported through OAM messaging
or via a YANG data model, and exposed to the Controller Plane.
5.3. RAW and DetNet
RAW leverages the DetNet Forwarding sub-layer and requires the
support of OAM in DetNet Transit Nodes (see Figure 3 of
[DetNet-ARCHI]) for the dynamic acquisition of link capacity and
state to maintain a strict RAW service, end-to-end, over a DetNet
Network. In turn, DetNet and thus RAW may benefit from / leverage
functionality such as provided by TSN at the lower layers.
RAW extends DetNet to improve the protection against link errors such
as transient flapping that are far more common in wireless links.
Nevertheless, the RAW methods are for the most part applicable to
wired links as well, e.g., when energy savings are desirable and the
available path diversity exceeds 1+1 linear redundancy.
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RAW adds sub-layer functions that operate in the DetNet Operational
Plane, which is part of the Network Plane. The RAW orientation
function may run only in the DetNet Edge Nodes (Ingress Edge Node or
End System), or it also run in DetNet Relay Nodes when the RAW
operations are distributed along the recovery graph. The RAW Service
sub-layer includes the PLR, which decides the DetNet Path for the
future packets of a flow along the DetNet Path, Maintenance End
Points (MEPs) on edge nodes, and Maintenance Intermediate Points
(MIPs) within. The MEPs trigger, and learn from, OAM observations,
and feed the PLR for its next decision.
As illustrated in Figure 5, RAW extends the DetNet Stack (see
Figure 4 of [DetNet-ARCHI] and Figure 3) with additional
functionality at the DetNet Service sub-layer for the actuation of
PREOF based on the PLR decision. DetNet operates at Layer-3,
leveraging abstractions of the lower layers and APIs that control
those abstractions. For instance, DetNet already leverages lower
layers for time-sensitive operations such as time synchronization and
traffic shapers. As the performances of the radio layers are subject
to rapid changes, RAW needs more dynamic gauges and knobs. To that
effect, the LL API provides an abstraction to the DetNet layer that
can be used to push reliability and timing hints like suggest X
retries (min, max) within a time window, or send unicast (one next
hop) or multicast (for overhearing). In the other direction up the
stack, the RAW PLR needs hints about the radio conditions such as L2
triggers (e.g., RSSI, LQI, or ETX) over all the wireless hops.
RAW uses various OAM functionalities at the different layers. For
instance, the OAM function in the DetNet Service sub-layer may
perform Active and/or Hybrid OAM to estimate the link and path
availability, end-to-end or limited to a Segment. The RAW functions
may be present in the Service sub-layer in DetNet Edge and Relay
Nodes.
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+-----------------+ +-------------------+
| Routing | | OAM Control |
+-----------------+ +-------------------+
Controller Plane
+-+-+-+-+-+-+-+-+ Southbound Interface -+-+-+-+-+-+-+-+-+-+-+-+
Network Plane
|
Operational Plane . Data Plane
|
+-----------------+ .
| Orientation | |
+-----------------+ .
|
+-----------------+ +-------------------+ .
| Point of | | OAM Maintenance | |
| local Repair | | End Point (MEP) | .
+-----------------+ +-------------------+ |
.
|
Figure 5: RAW function placement (Centralized Routing Case)
There are two main proposed models to deploy RAW and DetNet. In the
first model (strict) (illustrated in Figure 6), RAW operates over a
continuous DetNet Service end-to-end between the Ingress and the
Egress Edge Nodes or End Systems.
sIn the second model (loose), RAW may traverse a section of the
network that is not serviced by DetNet. RAW / OAM may observe the
end-to-end traffic and make the best of the available resources, but
it may not expect the DetNet guarantees over all paths. For
instance, the packets between two wireless entities may be relayed
over a wired infrastructure, in which case RAW observes and controls
the transmission over the wireless first and last hops, as well as
end-to-end metrics such as latency, jitter, and delivery ratio. This
operation is loose since the structure and properties of the wired
infrastructure are ignored, and may be either controlled by other
means such as DetNet/TSN, or neglected in the face of the wireless
hops.
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A minimal Forwarding sub-layer service is provided at all DetNet
Nodes to ensure that the OAM information flows. DetNet Relay Nodes
may or may not support RAW services, whereas the DetNet Edge Nodes
are required to support RAW in any case. DetNet guarantees, such as
bounded latency, are provided end-to-end. RAW extends the DetNet
Service sub-layer to optimize the use of resources.
--------------------Flow Direction---------------------------------->
+---------+
| RAW |
| Control |
+---------+ +---------+ +---------+
| RAW + | | RAW + | | RAW + |
| DetNet | | DetNet | | DetNet |
| Service | | Service | | Service |
+---------+---------------------------+---------+--------+---------+
| DetNet |
| Forwarding |
+------------------------------------------------------------------+
Ingress Transit Relay Egress
Edge ... Nodes ... Nodes ... Edge
Node Node
<------------------End-to-End DetNet Service----------------------->
Figure 6: (Strict) RAW over DetNet
In the second model (loose), illustrated in Figure 7, RAW operates
over a partial DetNet Service where typically only the Ingress and
the Egress End Systems support RAW. The DetNet Domain may extend
beyond the Ingress Node, or there may be a DetNet domain starting at
an Ingress Edge Node at the first hop after the End System.
In the loose model, RAW cannot observe the hops in the network, and
the path beyond the first hop is opaque; RAW can still observe the
end-to-end behavior and use Layer-3 measurements to decide whether to
replicate a packet and select the first-hop interface(s).
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--------------------Flow Direction---------------------------------->
+---------+
| RAW |
| Control |
+---------+ +---------+ +---------+
| RAW + | | DetNet | | RAW + |
| DetNet | | Only | | DetNet |
| Service | | Service | | Service |
+---------+----------------------+---+ +---+---------+
| DetNet |_______________| DetNet |
| Forwarding _______________ Forwarding |
+------------------------------------+ +-------------+
Ingress Transit Relay Tunnel Egress
End ... Nodes ... Nodes ... ... End
System System
<---------------Partitioned DetNet Service------------------------->
Figure 7: Loose RAW
6. The RAW Control Loop
The RAW Architecture is based on an abstract OODA Loop that controls
the operation of a Recovery Graph. The generic concept involves:
1. Operational Plane measurement protocols for OAM to observe (like
the first O in OODA) some or all hops along a recovery graph as
well as the end-to-end packet delivery.
2. The DetNet Controller Plane establish primary and protection
paths for use by the RAW Network Plane. The orientation function
reports data and information such as link statistics to be used
by the routing function to compute, install, and maintain the
recovery graphs. The routing function may also generate
intelligence such as a trained model for link quality prediction,
which in turn can be used by the orientation function (like the
second O in OODA) to influence the Path selection by the PLR
within the RAW OODA loop.
3. A PLR operates at the DetNet Service sub-layer and hosts the
decision function (like the D in OODA) of which DetNet Paths to
use for the future packets that are routed within the recovery
graph.
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4. Service protection actions that are actuated or triggered over
the LL API by the PLR to increase the reliability of the end-to-
end transmissions. The RAW architecture also covers in-situ
signaling that is embedded within live user traffic [RFC9378],
e.g., via OAM, when the decision is acted (like the A in OODA)
upon by a node that is downstream in the recovery graph from the
PLR.
The overall OODA Loop optimizes the use of redundancy to achieve the
required reliability and availability SLO(s) while minimizing the use
of constrained resources such as spectrum and battery.
6.1. Routing Time-Scale vs. Forwarding Time-Scale
With DetNet, the Controller Plane Function handles the routing
computation and maintenance. With RAW, the routing operation is
segregated from the RAW Control Loop, so it may reside in the
Controller Plane whereas the control loop itself happens in the
Network Plane. To achieve RAW capabilities, the routing operation is
extended to generate the information required by the orientation
function in the loop. The routing function may, e.g., propose DetNet
Paths to be used as a reflex action in response to network events, or
provide an aggregated history that the orientation function can use
to make a decision.
In a wireless mesh, the path to a routing function located in the
controller plane can be expensive and slow, possibly going across the
whole mesh and back. Reaching to the Controller Plane can also be
slow in regards to the speed of events that affect the forwarding
operation in the Network Plane at the radio layer. Note that a
distributed routing protocol may also take time and consume excessive
wireless resources to reconverge to a new optimized state.
As a result, the DetNet routing function is not expected to be aware
of and to react to very transient changes. The abstraction of a link
at the routing level is expected to use statistical metrics that
aggregate the behavior of a link over long periods of time, and
represent its properties as shades of gray as opposed to numerical
values such as a link quality indicator, or a Boolean value for
either up or down.
The interaction between the network nodes and the routing function is
handled by the orientation function, which builds reports to the
routing function and sends control information in a digested form
back to the RAW node, to be used inside a forwarding control loop for
traffic steering.
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Figure 8 illustrates a Network Plane recovery graph with links P-Q
and N-E flapping, possibly in a transient fashion due to a short-term
interferences, and possibly for a longer time, e.g., due to obstacles
between the sender and the receiver or hardware failures. In order
to maintain a received redundancy around a value of, say, 2, RAW may
leverage a higher ARQ on these hops if the overall latency permits
the extra delay, or enable alternate paths between ingress I and
egress E. For instance, RAW may enable protection path I ==> F ==> N
==> Q ==> M ==> R ==> E that routes around both issues and provides
some degree of spatial diversity with protection path I ==> A ==> B
==> C ==> D ==> E.
+----------------+
| DetNet |
| Routing |
+----------------+
^
|
Slow
| Controller Plane
_-._-._-._-._-._-. | ._-._-._-._-._-._-._-._-._-._-._-._-
_-._-._-._-._-._-._-. | _-._-._-._-._-._-._-._-._-._-._-._-
| Network Plane
Expensive
|
__...--- | ----.._.
.( | )-._
( v ).
( A--------B---C----D )
_ - / \ / \ --._
( I---F--------N--***-- E -
-_ \ / / )
( P--***---Q----M---R .
_ )- ._
- <------ Fast -------> )
( -._ .-
(_.___.._____________.____.._ __-____)
*** = flapping at this time
Figure 8: Time-Scales
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In the case of wireless, the changes that affect the forwarding
decision can happen frequently and often for short durations, e.g., a
mobile object moves between a transmitter and a receiver, and cancels
the line of sight transmission for a few seconds, or, a radar
measures the depth of a pool using the ISM band, and interferes on a
particular channel for a split second.
There is thus a desire to separate the long-term computation of the
route and the short-term forwarding decision. In that model, the
routing operation computes a recovery graph that enables multiple
Unequal Cost Multi-Path (UCMP) forwarding solutions along so-called
protection paths, and leaves it to the Network Plane to make the
short-term decision of which of these possibilities should be used
for which upcoming packets / flows.
In the context of Traffic Engineering (TE), an alternate path can be
used upon the detection of a failure in the main path, e.g., using
OAM in Multiprotocol Label Switching - Transport Profile (MPLS-TP) or
BFD over a collection of Software-Defined Wide Area Network (SD-WAN)
tunnels.
RAW formalizes a forwarding time-scale that may be order(s) of
magnitude shorter than the Controller Plane routing time-scale, and
separates the protocols and metrics that are used at both scales.
Routing can operate on long-term statistics such as delivery ratio
over minutes to hours, but as a first approximation can ignore the
cause of transient losses. On the other hand, the RAW forwarding
decision is made at the scale of a burst of packets, and uses
information that must be pertinent at the present time for the
current transmission(s).
6.2. OODA Loop
The RAW Architecture applies the generic OODA model to continuously
optimize the spectrum and energy used to forward packets within a
recovery graph, instantiating the OODA steps as follows:
Observe: Network Plane measurements, including protocols for OAM, to
Observe the local state of the links and some or all hops along a
recovery graph as well as the end-to-end packet delivery (see more
in Section 6.3). Information can also be provided by lower-layer
interfaces such as DLEP;
Orient: The orientation function, which reports data and information
such as the link statistics, and leverages offline-computed wisdom
and knowledge to Orient the PLR for its forwarding decision (see
more in Section 6.4);
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Decide: A local PLR that decides which DetNet Path to use for the
future packet(s) that are routed along the recovery graph (see
more in Section 6.5);
Act: PREOF Data Plane actions are controlled by the PLR over the LL
API to increase the reliability of the end-to-end transmission.
The RAW architecture also covers in-situ signaling when the
decision is Acted by a node that is down the recovery graph from
the PLR (see more in Section 6.6).
+-------> Orientation ---------+
| reflex actions |
| pre-trained model |
| |
......................................
| |
| Service sub-layer |
| v
Observe (OAM) Decide (PLR)
^ |
| |
| |
+------- Act (LL API) <--------+
Figure 9: The RAW OODA Loop
The overall OODA Loop optimizes the use of redundancy to achieve the
required reliability and availability Service Level Agreement (SLA)
while minimizing the use of constrained resources such as spectrum
and battery.
6.3. Observe: The RAW OAM
RAW In-situ OAM operation in the Network Plane may observe either a
full recovery graph or the DetNet Path that is being used at this
time. As packets may be load balanced, replicated, eliminated, and /
or fragmented for Network Coding FEC, the RAW In-situ operation needs
to be able to signal which operation occurred to an individual
packet.
Active RAW OAM may be needed to observe the unused segments and
evaluate the desirability of a rerouting decision.
Finally, the RAW Service sub-layer Assurance may observe the
individual PREOF operation of a DetNet Relay Node to ensure that it
is conforming; this might require injecting an OAM packet at an
upstream point inside the recovery graph and extracting that packet
at another point downstream before it reaches the egress.
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This observation feeds the RAW PLR that makes the decision on which
path is used at which RAW Node, for one packet or a small continuous
series of packets.
In the case of End-to-End Protection in a Wireless Mesh, the recovery
graph is strict and congruent with the path so all links are
observed.
Conversely, in the case of Radio Access Protection, illustrated in
Figure 10, the recovery graph is Loose and only the first hop is
observed; the rest of the path is abstracted and considered
infinitely reliable. The loss of a packet is attributed to the
first-hop Radio Access Network (RAN), even if a particular loss
effectively happens farther down the path. In that case, RAW enables
technology diversity (e.g., Wi-Fi and 5G), which in turn improves the
diversity in spectrum usage.
Opaque to OAM
<---------------------------->
.- .. - ..
RAN 1 --------( ).__
+-------+ / ( ). +------+
|Ingress|- __________Tunnel_______________|Egress|
| End |------ RAN 2 --_______________________________ End |
|System |- ( ) |System|
+-------+ \ ( ). +------+
RAN n ----( )
(_______...___.__...____....__..)
<-------L2------>
Observed by OAM
<----------------------L3----------------------->
Figure 10: Observed Links in Radio Access Protection
The Links that are not observed by OAM are opaque to it, meaning that
the OAM information is carried across and possibly echoed as data,
but there is no information captured in intermediate nodes. In the
example above, the Tunnel underlay is opaque and not controlled by
RAW; still the RAW OAM measures the end-to-end latency and delivery
ratio for packets sent via RAN 1, RAN 2, and RAN 3, and determines
whether a packet should be sent over either or a collection of those
access links.
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6.4. Orient: The RAW-extended DetNet Operational Plane
RAW separates the long time-scale at which a recovery graph is
computed and installed, from the short time-scale at which the
forwarding decision is taken for one or for a few packets (see
Section 6.1) that experience the same path until the network
conditions evolve and another path is selected within the same
recovery graph.
The recovery graph computation is out of scope, but RAW expects that
the CPF that installs the recovery graph also provides related
knowledge in the form of metadata about the links, segments, and
possible DetNet Paths. That metadata can be a pre-digested
statistical model, and may include prediction of future flaps and
packet loss, as well as recommended actions when that happens.
The metadata may include:
* A set of Pre-Determined DetNet Paths that are prepared to match
expected link-degradation profiles, so the DetNet Relay Nodes can
take reflex rerouting actions when facing a degradation that
matches one such profile;
* Link-Quality Statistics history and pre-trained models, e.g., to
predict the short-term variation of quality of the links in a
recovery graph.
The recovery graph is installed with measurable objectives that are
computed by the CPF to achieve the RAW SLA. The objectives can be
expressed as any of the maximum number of packets lost in a row,
bounded latency, maximal jitter, maximum number of interleaved out-
of-order packets, average number of copies received at the
elimination point, and maximal delay between the first and the last
received copy of the same packet.
6.5. Decide: The Point of Local Repair
The RAW OODA Loop operates at the path selection time-scale to
provide agility vs. the brute-force approach of flooding the whole
recovery graph. The OODA Loop controls, within the redundant
solutions that are proposed by the routing function, which is used
for each packet to provide a Reliable and Available service while
minimizing the waste of constrained resources.
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To that effect, RAW defines the Point of Local Repair (PLR), which
performs rapid local adjustments of the forwarding tables within the
path diversity that is available in that in the recovery graph. The
PLR enables exploitation of the richer forwarding capabilities at a
faster time-scale over a portion of the recovery graph, in either a
loose or a strict fashion.
The PLR operates on metrics that evolve faster, but that need to be
advertised at a fast rate but only locally, within the recovery
graph, and reacts on the metric updates by changing the DetNet path
in use for the affected flows.
The rapid changes in the forwarding decisions are made and contained
within the scope of a recovery graph and the actions of the PLR are
not signaled outside the recovery graph. This is as opposed to the
routing function that must observe the whole network and optimize all
the recovery graphs globally, which can only be done at a slow pace
and using long-term statistical metrics, as presented in Table 1.
+===============+=========================+=====================+
| | Controller Plane | PLR |
+===============+=========================+=====================+
| Communication | Slow, distributed | Fast, local |
+---------------+-------------------------+---------------------+
| Time-Scale | Path computation + | Lookup + protection |
| (order) | round trip, | switch, micro to |
| | milliseconds to seconds | milliseconds |
+---------------+-------------------------+---------------------+
| Network Size | Large, many recovery | Small, limited set |
| | graphs to optimize | of protection paths |
| | globally | |
+---------------+-------------------------+---------------------+
| Considered | Averaged, statistical, | Instantaneous |
| Metrics | shade of grey | values / boolean |
| | | condition |
+---------------+-------------------------+---------------------+
Table 1: Centralized Decision vs. PLR
The PLR sits in the DetNet Forwarding sub-layer of Edge and Relay
Nodes. The PLR operates on the packet flow, learning the recovery
graph and path-selection information from the packet, possibly making
a local decision and retagging the packet to indicate so. On the
other hand, the PLR interacts with the lower layers (through triggers
and DLEP) and with its peers (through OAM) to obtain up-to-date
information about its links and the quality of the overall recovery
graph, respectively, as illustrated in Figure 11.
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|
packet | going
down the | stack
+==========v==========+=====================+===================+
|(In-situ OAM + iCTRL)| (L2 Triggers, DLEP) | (Hybrid OAM) |
+==========v==========+=====================+===================+
| Learn from | | Learn from |
| packet tagging > Maintain < end-to-end |
+----------v----------+ Forwarding | OAM packets |
| Forwarding decision < State +---------^---------|
+----------v----------+ | Enrich or |
+ Retag Packet | Learn abstracted > Regenerate |
| and Forward | metrics about Links | OAM packets |
+..........v..........+..........^..........+........^.v........+
| Lower layers |
+..........v.....................^...................^.v........+
frame | sent Frame | L2 Ack Active | | OAM
over | wireless In | In and | | out
v | | v
Figure 11: PLR Conceptual Interfaces
6.6. Act: DetNet Path Selection and Reliability Functions
The main action by the PLR is the swapping of the DetNet Path within
the recovery graph for the future packets. The candidate DetNet
Paths represent different energy and spectrum profiles, and provide
protection against different failures.
The LL API enriches the DetNet protection services (PREOF) with
potential possibility to interact with lower-layer one-hop
reliability functions that are more typical to wireless than wired,
including ARQ, FEC, and other techniques such as overhearing and
constructive interferences. Because RAW may be leveraged on wired
links, e.g., to save power, it is not expected that all lower layers
support all those capabilities.
RAW provides hints to the lower-layer services on the desired
outcome, and the lower layer acts on those hints to provide the best
approximation of that outcome, e.g., a level of reliability for one-
hop transmission within a bounded budget of time and/or energy.
Thus, the LL API makes possible cross-layer optimization for
reliability depending on the actual abstraction provided. That is,
some reliability functions are controlled from Layer-3 using an
abstract interface, while they are really operated at the lower
layers.
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The RAW Path Selection can be implemented in both centralized and
distributed approaches. In the centralized approach, the PLR may
obtain a set of pre-computed DetNet paths matching a set of expected
failures, and apply the appropriate DetNet paths for the current
state of the wireless links. In the distributed approach, the
signaling in the packet may be more abstract than an explicit Path,
and the PLR decision might be revised along the selected DetNet Path
based on a better knowledge of the rest of the way.
The dynamic DetNet Path selection in RAW avoids the waste of critical
resources such as spectrum and energy while providing for the assured
SLA, e.g., by rerouting and/or adding redundancy only when a loss
spike is observed.
7. Security Considerations
7.1. Collocated Denial of Service Attacks
RAW leverages diversity (e.g., spatial and time diversity, coding
diversity, and frequency diversity), possibly using heterogeneous
wired and wireless networking technologies over different physical
paths, to increase the reliability and availability in the face of
unpredictable conditions. While this is not done specifically to
defeat an attacker, the amount of diversity used in RAW defeats
possible attacks that would impact a particular technology or a
specific path.
Physical actions by a collocated attacker such as a radio
interference may still lower the reliability of an end-to-end RAW
transmission by blocking one segment or one possible path. But if an
alternate path with diverse frequency, location, and/or technology,
is available, then RAW adapts by rerouting the impacted traffic over
the preferred alternates, which defeats the attack after a limited
period of lower reliability. Then again, the security benefit is a
side-effect of an action that is taken regardless of whether the
source of the issue is voluntary (an attack) or not.
7.2. Layer-2 encryption
Radio networks typically encrypt at the MAC layer to protect the
transmission. If the encryption is per-pair of peers, then certain
RAW operations like promiscuous overhearing become impractical.
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7.3. Forced Access
A RAW policy may typically select the cheapest collection of links
that matches the requested SLA, e.g., use free Wi-Fi vs. paid 3GPP
access. By defeating the cheap connectivity (e.g., PHY-layer
interference) the attacker can force an End System to use the paid
access and increase the cost of the transmission for the user.
Similar attacks may also be used to deplete resources in lower-power
nodes by forcing additional transmissions for FEC and ARQ, and attack
metrics such as battery life of the nodes. By affecting the
transmissions and the associated routing metrics in one area, an
attacker may force the traffic and cause congestion along a remote
path, thus reducing the overall throughput of the network.
8. IANA Considerations
This document has no IANA actions.
9. Contributors
The editor wishes to thank the following individuals for their
contributions to the text and ideas exposed in this document:
Lou Berger: LabN Consulting, L.L.C, lberger@labn.net
Xavi Vilajosana: Wireless Networks Research Lab, Universitat Oberta
de Catalunya, xvilajosana@gmail.com
Geogios Papadopolous: IMT Atlantique , georgios.papadopoulos@imt-
atlantique.fr
Remous-Aris Koutsiamanis: IMT Atlantique, remous-
aris.koutsiamanis@imt-atlantique.fr
Rex Buddenberg: retired, buddenbergr@gmail.com
Greg Mirsky: Ericsson, gregimirsky@gmail.com
10. Acknowledgments
This architecture could never have been completed without the support
and recommendations from the DetNet Chairs Janos Farkas and Lou
Berger, and Dave Black, the DetNet Tech Advisor. Many thanks to all
of you.
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The authors wish to thank Ketan Talaulikar, as well as Balazs Varga,
Dave Cavalcanti, Don Fedyk, Nicolas Montavont, and Fabrice Theoleyre
for their in-depth reviews during the development of this document.
The authors wish to thank Acee Lindem, Eva Schooler, Rich Salz,
Wesley Eddy, Behcet Sarikaya, Brian Haberman, Gorry Fairhurst, Eric
Vyncke, Erik Kline, Roman Danyliw, and Dave Thaler, for their reviews
and comments during the IETF Last Call / IESG review cycle.
Special thanks for Mohamed Boucadair, Giuseppe Fioccola, and Benoit
Claise, for their help dealing with OAM technologies.
11. References
11.1. Normative References
[RAW-TECHNOS]
Thubert, P., Cavalcanti, D., Vilajosana, X., Schmitt, C.,
and J. Farkas, "Reliable and Available Wireless (RAW)
Technologies", Work in Progress, Internet-Draft, draft-
ietf-raw-technologies-17, 15 April 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-raw-
technologies-17>.
[TSN] IEEE, "Time-Sensitive Networking (TSN)",
<https://1.ieee802.org/tsn/>.
[6TiSCH-ARCHI]
Thubert, P., Ed., "An Architecture for IPv6 over the Time-
Slotted Channel Hopping Mode of IEEE 802.15.4 (6TiSCH)",
RFC 9030, DOI 10.17487/RFC9030, May 2021,
<https://www.rfc-editor.org/info/rfc9030>.
[RFC4427] Mannie, E., Ed. and D. Papadimitriou, Ed., "Recovery
(Protection and Restoration) Terminology for Generalized
Multi-Protocol Label Switching (GMPLS)", RFC 4427,
DOI 10.17487/RFC4427, March 2006,
<https://www.rfc-editor.org/info/rfc4427>.
[RFC6291] Andersson, L., van Helvoort, H., Bonica, R., Romascanu,
D., and S. Mansfield, "Guidelines for the Use of the "OAM"
Acronym in the IETF", BCP 161, RFC 6291,
DOI 10.17487/RFC6291, June 2011,
<https://www.rfc-editor.org/info/rfc6291>.
[RFC7799] Morton, A., "Active and Passive Metrics and Methods (with
Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799,
May 2016, <https://www.rfc-editor.org/info/rfc7799>.
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[RFC8557] Finn, N. and P. Thubert, "Deterministic Networking Problem
Statement", RFC 8557, DOI 10.17487/RFC8557, May 2019,
<https://www.rfc-editor.org/info/rfc8557>.
[DetNet-ARCHI]
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>.
[DetNet-OAM]
Mirsky, G., Theoleyre, F., Papadopoulos, G., Bernardos,
CJ., Varga, B., and J. Farkas, "Framework of Operations,
Administration, and Maintenance (OAM) for Deterministic
Networking (DetNet)", RFC 9551, DOI 10.17487/RFC9551,
March 2024, <https://www.rfc-editor.org/info/rfc9551>.
11.2. Informative References
[RFC9049] Dawkins, S., Ed., "Path Aware Networking: Obstacles to
Deployment (A Bestiary of Roads Not Taken)", RFC 9049,
DOI 10.17487/RFC9049, June 2021,
<https://www.rfc-editor.org/info/rfc9049>.
[INT-ARCHI]
Braden, R., Ed., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122,
DOI 10.17487/RFC1122, October 1989,
<https://www.rfc-editor.org/info/rfc1122>.
[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>.
[RFC8578] Grossman, E., Ed., "Deterministic Networking Use Cases",
RFC 8578, DOI 10.17487/RFC8578, May 2019,
<https://www.rfc-editor.org/info/rfc8578>.
[RAW-USE-CASES]
Bernardos, C. J., Papadopoulos, G. Z., Thubert, P., and F.
Theoleyre, "RAW Use-Cases", Work in Progress, Internet-
Draft, draft-ietf-raw-use-cases-11, 17 April 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-raw-use-
cases-11>.
Thubert Expires 26 January 2026 [Page 42]
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[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981,
<https://www.rfc-editor.org/info/rfc791>.
[RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, DOI 10.17487/RFC2205,
September 1997, <https://www.rfc-editor.org/info/rfc2205>.
[TE] Farrel, A., Ed., "Overview and Principles of Internet
Traffic Engineering", RFC 9522, DOI 10.17487/RFC9522,
January 2024, <https://www.rfc-editor.org/info/rfc9522>.
[RFC9544] Mirsky, G., Halpern, J., Min, X., Clemm, A., Strassner,
J., and J. François, "Precision Availability Metrics
(PAMs) for Services Governed by Service Level Objectives
(SLOs)", RFC 9544, DOI 10.17487/RFC9544, March 2024,
<https://www.rfc-editor.org/info/rfc9544>.
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC3366] Fairhurst, G. and L. Wood, "Advice to link designers on
link Automatic Repeat reQuest (ARQ)", BCP 62, RFC 3366,
DOI 10.17487/RFC3366, August 2002,
<https://www.rfc-editor.org/info/rfc3366>.
[RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast
Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
DOI 10.17487/RFC4090, May 2005,
<https://www.rfc-editor.org/info/rfc4090>.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<https://www.rfc-editor.org/info/rfc5880>.
[FRR] Shand, M. and S. Bryant, "IP Fast Reroute Framework",
RFC 5714, DOI 10.17487/RFC5714, January 2010,
<https://www.rfc-editor.org/info/rfc5714>.
[RFC6378] Weingarten, Y., Ed., Bryant, S., Osborne, E., Sprecher,
N., and A. Fulignoli, Ed., "MPLS Transport Profile (MPLS-
TP) Linear Protection", RFC 6378, DOI 10.17487/RFC6378,
October 2011, <https://www.rfc-editor.org/info/rfc6378>.
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[RFC6551] Vasseur, JP., Ed., Kim, M., Ed., Pister, K., Dejean, N.,
and D. Barthel, "Routing Metrics Used for Path Calculation
in Low-Power and Lossy Networks", RFC 6551,
DOI 10.17487/RFC6551, March 2012,
<https://www.rfc-editor.org/info/rfc6551>.
[RLFA-FRR] Bryant, S., Filsfils, C., Previdi, S., Shand, M., and N.
So, "Remote Loop-Free Alternate (LFA) Fast Reroute (FRR)",
RFC 7490, DOI 10.17487/RFC7490, April 2015,
<https://www.rfc-editor.org/info/rfc7490>.
[RFC8724] Minaburo, A., Toutain, L., Gomez, C., Barthel, D., and JC.
Zuniga, "SCHC: Generic Framework for Static Context Header
Compression and Fragmentation", RFC 8724,
DOI 10.17487/RFC8724, April 2020,
<https://www.rfc-editor.org/info/rfc8724>.
[DetNet-DP]
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>.
[DLEP] Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and B.
Berry, "Dynamic Link Exchange Protocol (DLEP)", RFC 8175,
DOI 10.17487/RFC8175, June 2017,
<https://www.rfc-editor.org/info/rfc8175>.
[RFC9378] Brockners, F., Ed., Bhandari, S., Ed., Bernier, D., and T.
Mizrahi, Ed., "In Situ Operations, Administration, and
Maintenance (IOAM) Deployment", RFC 9378,
DOI 10.17487/RFC9378, April 2023,
<https://www.rfc-editor.org/info/rfc9378>.
[RFC8762] Mirsky, G., Jun, G., Nydell, H., and R. Foote, "Simple
Two-Way Active Measurement Protocol", RFC 8762,
DOI 10.17487/RFC8762, March 2020,
<https://www.rfc-editor.org/info/rfc8762>.
[RFC9473] Enghardt, R. and C. Krähenbühl, "A Vocabulary of Path
Properties", RFC 9473, DOI 10.17487/RFC9473, September
2023, <https://www.rfc-editor.org/info/rfc9473>.
[RFC9633] Geng, X., Ryoo, Y., Fedyk, D., Rahman, R., and Z. Li,
"Deterministic Networking (DetNet) YANG Data Model",
RFC 9633, DOI 10.17487/RFC9633, October 2024,
<https://www.rfc-editor.org/info/rfc9633>.
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[I-D.ietf-detnet-controller-plane-framework]
Malis, A. G., Geng, X., Chen, M., Varga, B., and C. J.
Bernardos, "Deterministic Networking (DetNet) Controller
Plane Framework", Work in Progress, Internet-Draft, draft-
ietf-detnet-controller-plane-framework-12, 27 June 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-detnet-
controller-plane-framework-12>.
[NASA1] Adams, T., "RELIABILITY: Definition & Quantitative
Illustration", <https://extapps.ksc.nasa.gov/Reliability/
Documents/150814-3bWhatIsReliability.pdf>.
[NASA2] Adams, T., "Availability",
<https://extapps.ksc.nasa.gov/Reliability/
Documents/160727.1_Availability_What_is_it.pdf>.
Author's Address
Pascal Thubert (editor)
Without Affiliation
06330 Roquefort-les-Pins
France
Email: pascal.thubert@gmail.com
Thubert Expires 26 January 2026 [Page 45]
