< draft-ietf-raw-architecture-02.txt   draft-ietf-raw-architecture-03.txt >
RAW P. Thubert, Ed. RAW P. Thubert, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Intended status: Informational G.Z. Papadopoulos Intended status: Informational G.Z. Papadopoulos
Expires: 2 June 2022 IMT Atlantique Expires: 18 July 2022 IMT Atlantique
29 November 2021 14 January 2022
Reliable and Available Wireless Architecture Reliable and Available Wireless Architecture
draft-ietf-raw-architecture-02 draft-ietf-raw-architecture-03
Abstract Abstract
Reliable and Available Wireless (RAW) provides for high reliability Reliable and Available Wireless (RAW) provides for high reliability
and availability for IP connectivity over a wireless medium. The and availability for IP connectivity over a wireless medium. The
wireless medium presents significant challenges to achieve wireless medium presents significant challenges to achieve
deterministic properties such as low packet error rate, bounded deterministic properties such as low packet error rate, bounded
consecutive losses, and bounded latency. This document defines the consecutive losses, and bounded latency. This document defines the
RAW Architecture following an OODA loop that involves OAM, PCE, PSE RAW Architecture following an OODA loop that involves OAM, PCE, PSE
and PAREO functions. It builds on the DetNet Architecture and and PAREO functions. It builds on the DetNet Architecture and
skipping to change at page 1, line 41 skipping to change at page 1, line 41
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This Internet-Draft will expire on 2 June 2022. This Internet-Draft will expire on 18 July 2022.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. The RAW problem . . . . . . . . . . . . . . . . . . . . . . . 5 2. The RAW problem . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2.1.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . 6 2.1.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . 6
2.1.2. Link and Direction . . . . . . . . . . . . . . . . . 6 2.1.2. Link and Direction . . . . . . . . . . . . . . . . . 7
2.1.3. Path and Tracks . . . . . . . . . . . . . . . . . . . 7 2.1.3. Path and Tracks . . . . . . . . . . . . . . . . . . . 7
2.1.4. Deterministic Networking . . . . . . . . . . . . . . 8 2.1.4. Deterministic Networking . . . . . . . . . . . . . . 8
2.1.5. Reliability and Availability . . . . . . . . . . . . 9 2.1.5. Reliability and Availability . . . . . . . . . . . . 9
2.1.6. OAM variations . . . . . . . . . . . . . . . . . . . 10 2.1.6. OAM variations . . . . . . . . . . . . . . . . . . . 10
2.2. Reliability and Availability . . . . . . . . . . . . . . 11 2.2. Reliability and Availability . . . . . . . . . . . . . . 11
2.2.1. High Availability Engineering Principles . . . . . . 11 2.2.1. High Availability Engineering Principles . . . . . . 12
2.2.2. Applying Reliability Concepts to Networking . . . . . 14 2.2.2. Applying Reliability Concepts to Networking . . . . . 14
2.2.3. Reliability in the Context of RAW . . . . . . . . . . 15 2.2.3. Reliability in the Context of RAW . . . . . . . . . . 15
2.3. Routing Time Scale vs. Forwarding Time Scale . . . . . . 16 2.3. Routing Time Scale vs. Forwarding Time Scale . . . . . . 16
3. The RAW Conceptual Model . . . . . . . . . . . . . . . . . . 18 3. The RAW Conceptual Model . . . . . . . . . . . . . . . . . . 18
4. The OODA Loop . . . . . . . . . . . . . . . . . . . . . . . . 20 4. The OODA Loop . . . . . . . . . . . . . . . . . . . . . . . . 20
5. Observe: The RAW OAM . . . . . . . . . . . . . . . . . . . . 21 4.1. Observe: The RAW OAM . . . . . . . . . . . . . . . . . . 21
6. Orient: The Path Computation Engine . . . . . . . . . . . . . 22 4.2. Orient: The Path Computation Engine . . . . . . . . . . . 22
7. Decide: The Path Selection Engine . . . . . . . . . . . . . . 22 4.3. Decide: The Path Selection Engine . . . . . . . . . . . . 22
8. Act: The PAREO Functions . . . . . . . . . . . . . . . . . . 24 4.4. Act: The PAREO Functions . . . . . . . . . . . . . . . . 24
8.1. Packet Replication . . . . . . . . . . . . . . . . . . . 25 4.4.1. Packet Replication . . . . . . . . . . . . . . . . . 25
8.2. Packet Elimination . . . . . . . . . . . . . . . . . . . 26 4.4.2. Packet Elimination . . . . . . . . . . . . . . . . . 26
8.3. Promiscuous Overhearing . . . . . . . . . . . . . . . . . 26 4.4.3. Promiscuous Overhearing . . . . . . . . . . . . . . . 26
8.4. Constructive Interference . . . . . . . . . . . . . . . . 27 4.4.4. Constructive Interference . . . . . . . . . . . . . . 27
9. Security Considerations . . . . . . . . . . . . . . . . . . . 27 5. Security Considerations . . . . . . . . . . . . . . . . . . . 27
9.1. Forced Access . . . . . . . . . . . . . . . . . . . . . . 27 5.1. Forced Access . . . . . . . . . . . . . . . . . . . . . . 27
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 27 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 28
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 28 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 28
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 28 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 28
13.1. Normative References . . . . . . . . . . . . . . . . . . 28 9.1. Normative References . . . . . . . . . . . . . . . . . . 28
13.2. Informative References . . . . . . . . . . . . . . . . . 29 9.2. Informative References . . . . . . . . . . . . . . . . . 30
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31
1. Introduction 1. Introduction
Deterministic Networking is an attempt to emulate the properties of a Deterministic Networking is an attempt to emulate the properties of a
serial link over a switched fabric, by providing a bounded latency serial link over a switched fabric, by providing a bounded latency
and eliminating congestion loss, even when co-existing with best- and eliminating congestion loss, even when co-existing with best-
effort traffic. It is getting traction in various industries effort traffic. It is getting traction in various industries
including professional A/V, manufacturing, online gaming, and including professional A/V, manufacturing, online gaming, and
smartgrid automation, enabling cost and performance optimizations smartgrid automation, enabling cost and performance optimizations
(e.g., vs. loads of P2P cables). (e.g., vs. loads of P2P cables).
Bringing determinism in a packet network means eliminating the Bringing determinism in a packet network means eliminating the
statistical effects of multiplexing that result in probabilistic statistical effects of multiplexing that result in probabilistic
jitter and loss. This can be approached with a tight control of the jitter and loss. This can be approached with a tight control of the
physical resources to maintain the amount of traffic within a physical resources to maintain the amount of traffic within a
budgetted volume of data per unit of time that fits the physical budgeted volume of data per unit of time that fits the physical
capabilities of the underlying network, and the use of time-shared capabilities of the underlying network, and the use of time-shared
resources (bandwidth and buffers) per circuit, and/or by shaping and/ resources (bandwidth and buffers) per circuit, and/or by shaping and/
or scheduling the packets at every hop. or scheduling the packets at every hop.
This innovation was initially introduced on wired networks, with IEEE This innovation was initially introduced on wired networks, with IEEE
802.1 Time Sensitive networking (TSN) - for Ethernet LANs - and IETF 802.1 Time Sensitive networking (TSN) - for Ethernet LANs - and IETF
DetNet. But the wired and the wireless media are fundamentally DetNet. But the wired and the wireless media are fundamentally
different at the physical level and in the possible abstractions that different at the physical level and in the possible abstractions that
can be built for IPv6 [IPoWIRELESS]. Nevertheless, deterministic can be built for IPv6 [IPoWIRELESS]. Nevertheless, deterministic
capabilities are required in a number of wireless use cases as well capabilities are required in a number of wireless use cases as well
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layer-3. layer-3.
While the generic "Deterministic Networking Problem Statement" While the generic "Deterministic Networking Problem Statement"
[RFC8557] applies to both the wired and the wireless media, the [RFC8557] applies to both the wired and the wireless media, the
methods to achieve RAW must extend those used to support time- methods to achieve RAW must extend those used to support time-
sensitive networking over wires, as a RAW solution has to address sensitive networking over wires, as a RAW solution has to address
less consistent transmissions, energy conservation and shared less consistent transmissions, energy conservation and shared
spectrum efficiency. spectrum efficiency.
RAW provides DetNet elements that are specialized for IPv6 flows RAW provides DetNet elements that are specialized for IPv6 flows
[IPv6] over deterministic short range radios [RAW-TECHNOS]. [IPv6] over selected deterministic radios technologies [RAW-TECHNOS].
Conceptually, RAW is agnostic to the radio layer underneath though Conceptually, RAW is agnostic to the radio layer underneath though
the capability to schedule transmissions is assumed. How the PHY is the capability to schedule transmissions is assumed. How the PHY is
programmed to do so, and whether the radio is single-hop or meshed, programmed to do so, and whether the radio is single-hop or meshed,
are unknown at the IP layer and not part of the RAW abstraction. are unknown at the IP layer and not part of the RAW abstraction.
Nevertheless, cross-layer optimizations may take place to ensure Nevertheless, cross-layer optimizations may take place to ensure
proper link awareness (think, link quality) and packet handling proper link awareness (think, link quality) and packet handling
(think, scheduling). (think, scheduling).
The "Deterministic Networking Architecture" [RFC8655] is composed of The "Deterministic Networking Architecture" [RFC8655] is composed of
three planes: the Application (User) Plane, the Controller Plane, and three planes: the Application (User) Plane, the Controller Plane, and
the Network Plane. The RAW Architecture extends the DetNet Network the Network Plane. The RAW Architecture extends the DetNet Network
Plane, to accommodate one or multiple hops of homogeneous or Plane, to accommodate one or multiple hops of homogeneous or
heterogeneous wireless technologies, e.g. a Wi-Fi6 Mesh or parallel heterogeneous wireless technologies, e.g. a Wi-Fi6 Mesh or parallel
CBRS access links federated by a 5G backhaul. CBRS access links federated by a 5G backhaul.
RAW and DetNet associate application that that require a particular RAW and DetNet route application flows that require a special
treatment to a path that was provisionned to procure that treatment. treatment along the paths that will provide that treatment. This may
This may be seen as a form of Path Aware Networking and may be be seen as a form of Path Aware Networking and may be subject to
subject to impediments documented in [RFC9049]. impediments documented in [RFC9049].
The establishment of a path is not in-scope for RAW. It may be the The establishment of a path is not in-scope for RAW. It may be the
product of a centralized Controller Plane as described for DetNet. product of a centralized Controller Plane as described for DetNet.
As opposed to wired networks, the action of installing a path over a 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 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 the radio conditions vary, and it makes sense in the wireless case to
provide redundant forwarding solutions along a complex path and to provide redundant forwarding solutions along a complex path and to
leave it to the Network Plane to select which of those forwarding 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 solutions are to be used for a given packet based on the current
conditions. conditions.
RAW distinguishes the longer time scale at which routes are computed RAW distinguishes the longer time scale at which routes are computed
from the the shorter forwarding time scale where per-packet decisions from the the shorter forwarding time scale where per-packet decisions
are made. RAW operates within the Network Plane at the forwarding are made. RAW operates within the Network Plane at the forwarding
time scale on one DetNet flow over a complex path called a Track. time scale on one DetNet flow over a complex path called a Track.
The Track is preestablished and installed by means outside of the The Track is preestablished and installed by means outside of the
scope of RAW; it may be strict or loose depending on whether each or scope of RAW; it may be strict or loose depending on whether each or
just a subset of the hops are observed and controlled by RAW. just a subset of the hops are observed and controlled by RAW.
The RAW Architecture is structured as an OODA Loop (Observe, Orient, The RAW Architecture is based on an abstract OODA Loop (Observe,
Decide, Act). It involves: Orient, Decide, Act). The generic concept involves:
1. Network Plane measurement protocols for Operations, 1. Network Plane measurement protocols for Operations,
Administration and Maintenance (OAM) to Observe some or all hops Administration and Maintenance (OAM) to Observe some or all hops
along a Track as well as the end-to-end packet delivery along a Track as well as the end-to-end packet delivery
2. Controller plane elements to reports the links statistics to a 2. Controller plane elements to reports the links statistics to a
Path computation Element (PCE) in a centralized controller that Path computation Element (PCE) in a centralized controller that
computes and installs the Tracks and provides meta data to Orient computes and installs the Tracks and provides meta data to Orient
the routing decision the routing decision
3. A Runtime distributed Path Selection Engine (PSE) that Decides 3. A Runtime distributed Path Selection Engine (PSE) that Decides
which subTrack to use for the next packet(s) that are routed which subTrack to use for the next packet(s) that are routed
along the Track along the Track
4. Packet (hybrid) ARQ, Replication, Elimination and Ordering 4. Packet (hybrid) ARQ, Replication, Elimination and Ordering
Dataplane actions that operate at the DetNet Service Layer to Dataplane actions that operate at the DetNet Service Layer to
increase the reliability of the end-to-end transmission. The RAW increase the reliability of the end-to-end transmissions. The
architecture also covers in-situ signalling when the decision is RAW architecture also covers in-situ signalling when the decision
Acted by a node that down the Track from the PSE. is Acted by a node that down the Track from the PSE.
The overall OODA Loop optimizes the use of redundancy to achieve the The overall OODA Loop optimizes the use of redundancy to achieve the
required reliability and availability Service Level Agreement (SLA) required reliability and availability Service Level Agreement (SLA)
while minimizing the use of constrained resources such as spectrum while minimizing the use of constrained resources such as spectrum
and battery. and battery.
This document presents the RAW problem and associated terminology in
Section 2, and elaborates in Section 4 on the OODA loop based on the
RAW conceptual model presented in Section 3.
2. The RAW problem 2. The RAW problem
2.1. Terminology 2.1. Terminology
RAW reuses terminology defined for DetNet in the "Deterministic RAW reuses terminology defined for DetNet in the "Deterministic
Networking Architecture" [RFC8655], e.g., PREOF for Packet Networking Architecture" [RFC8655], e.g., PREOF for Packet
Replication, Elimination and Ordering Functions. Replication, Elimination and Ordering Functions.
RAW also reuses terminology defined for 6TiSCH in [6TiSCH-ARCHI] such RAW also reuses terminology defined for 6TiSCH in [6TiSCH-ARCHI] such
as the term Track. A Track as a complex path with associated PAREO as the term Track. A Track associates a complex path with PAREO and
operations. The concept is abstract to the underlaying technology shaping operations. The concept is agnostic to the underlaying
and applies to any fully or partially wireless mesh, including, e.g., technology and applies to any fully or partially wireless mesh,
a Wi-Fi mesh. RAW specifies strict and loose Tracks depending on including, e.g., a Wi-Fi mesh. RAW specifies strict and loose Tracks
whether the path is fully controlled by RAW or traverses an opaque depending on whether the path is fully controlled by RAW or traverses
network where RAW cannot observe and control the individual hops. an opaque network where RAW cannot observe and control the individual
hops.
RAW uses the following terminology and acronyms: RAW uses the following terminology and acronyms:
2.1.1. Acronyms 2.1.1. Acronyms
2.1.1.1. ARQ 2.1.1.1. ARQ
Automatic Repeat Request, enabling an acknowledged transmission and Automatic Repeat Request, enabling an acknowledged transmission and
retries. ARQ is a typical model at Layer-2 on a wireless medium. It retries. ARQ is a typical model at Layer-2 on a wireless medium.
is typically avoided end-to-end on deterministic flows because it ARQ is typically implemented hop-by-hop and not end-to-end in
introduces excessive indetermination in latency, but a limited number wireless networks. Else, it introduces excessive indetermination in
of retries within a bounded time may be used over a wireless link and latency, but a limited number of retries within a bounded time may be
yet respect end-to-end constraints. used within end-to-end constraints.
2.1.1.2. OAM 2.1.1.2. OAM
OAM stands for Operations, Administration, and Maintenance, and OAM stands for Operations, Administration, and Maintenance, and
covers the processes, activities, tools, and standards involved with covers the processes, activities, tools, and standards involved with
operating, administering, managing and maintaining any system. This operating, administering, managing and maintaining any system. This
document uses the terms Operations, Administration, and Maintenance, document uses the terms Operations, Administration, and Maintenance,
in conformance with the 'Guidelines for the Use of the "OAM" Acronym 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 in the IETF' [RFC6291] and the system observed by the RAW OAM is the
Track. Track.
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Observe, Orient, Decide, Act. The OODA Loop is a conceptual cyclic Observe, Orient, Decide, Act. The OODA Loop is a conceptual cyclic
model developed by USAF Colonel John Boyd, and that is applicable in model developed by USAF Colonel John Boyd, and that is applicable in
multiple domains where agility can provide benefits against brute multiple domains where agility can provide benefits against brute
force. force.
2.1.1.4. PAREO 2.1.1.4. PAREO
Packet (hybrid) ARQ, Replication, Elimination and Ordering. PAREO is Packet (hybrid) ARQ, Replication, Elimination and Ordering. PAREO is
a superset Of DetNet's PREOF that includes radio-specific techniques a superset Of DetNet's PREOF that includes radio-specific techniques
such as short range broadcast, MUMIMO, constructive interference and such as short range broadcast, MUMIMO, PHY rate and other Modulation
Coding Scheme (MCS) adaptation, constructive interference and
overhearing, which can be leveraged separately or combined to overhearing, which can be leveraged separately or combined to
increase the reliability. increase the reliability.
2.1.2. Link and Direction 2.1.2. Link and Direction
2.1.2.1. Flapping 2.1.2.1. Flapping
In the context of RAW, a link flaps when the reliability of the In the context of RAW, a link flaps when the reliability of the
wireless connectivity drops abruptly for a short period of time, wireless connectivity drops abruptly for a short period of time,
typically of a subsecond to seconds duration. typically of a subsecond to seconds duration.
2.1.2.2. Uplink 2.1.2.2. Uplink
Connection from end-devices to a data communication equipment. In Connection from end-devices to a data communication equipment. In
the context of wireless, uplink refers to the connection between a the context of wireless, uplink refers to the connection between a
station (STA) and a controller (AP) or a User Equipment (UE) to a station (STA) and a controller (AP) or a User Equipment (UE) to a
Base Station (BS) such as a 3GPP 5G gNodeB (gNb). Base Station (BS) such as a 3GPP 5G gNodeB (gNb).
2.1.2.3. Downlink 2.1.2.3. Downlink
The reverse direction from uplink. The reverse direction from uplink.
2.1.2.4. Downstream 2.1.2.4. Downstream
Following the the direction of the flow data path along a Track. Following the direction of the flow data path along a Track.
2.1.2.5. Upstream 2.1.2.5. Upstream
Against the direction of the flow data path along a Track. Against the direction of the flow data path along a Track.
2.1.3. Path and Tracks 2.1.3. Path and Tracks
2.1.3.1. Path 2.1.3.1. Path
Quoting section 1.1.3 of [INT-ARCHI]: Quoting section 1.1.3 of [INT-ARCHI]:
| "At a given moment, all the IP datagrams from a particular source | At a given moment, all the IP datagrams from a particular source
| host to a particular destination host will typically traverse the | host to a particular destination host will typically traverse the
| same sequence of gateways. We use the term "path" for this | same sequence of gateways. We use the term "path" for this
| sequence. Note that a path is uni-directional; it is not unusual | sequence. Note that a path is uni-directional; it is not unusual
| to have different paths in the two directions between a given host | to have different paths in the two directions between a given host
| pair.". | pair.
Section 2 of [I-D.irtf-panrg-path-properties] points to a longer, Section 2 of [I-D.irtf-panrg-path-properties] points to a longer,
more modern definition of path, which begins as follows: more modern definition of path, which begins as follows:
| A sequence of adjacent path elements over which a packet can be | A sequence of adjacent path elements over which a packet can f be
| transmitted, starting and ending with a node. A path is | transmitted, starting and ending with a node. A path is
| unidirectional. Paths are time-dependent, i.e., the sequence of | unidirectional. Paths are time-dependent, i.e., the sequence of
| path elements over which packets are sent from one node to another | path elements over which packets are sent from one node to another
| may change. A path is defined between two nodes. | may change. A path is defined between two nodes.
It follows that the general acceptance of a path is a linear sequence It follows that the general acceptance of a path is a linear sequence
of nodes, as opposed to a multi-dimensional graph. In the context of of nodes, as opposed to a multi-dimensional graph. In the context of
this document, a path is observed by following one copy of a packet this document, a path is observed by following one copy of a packet
that is injected in a Track and possibly replicated within. that is injected in a Track and possibly replicated within.
2.1.3.2. Track 2.1.3.2. Track
A networking graph that can be followed to transport packets with A networking graph that can be followed to transport packets with
equivalent treatment; as opposed to the definition of a path above, a equivalent treatment; as opposed to the definition of a path above, a
Track Track is not necessarily linear. It may contain multiple paths Track is not necessarily a linear sequence. It may contain multiple
that may fork and rejoin, for instance to enable the RAW PAREO paths that may fork and rejoin, for instance to enable the RAW PAREO
operations. operations.
In DetNet [RFC8655] terms, a Track has the following properties: In DetNet [RFC8655] terms, a Track has the following properties:
* A Track has one Ingress and one Egress nodes, which operate as * A Track has one Ingress and one Egress nodes, which operate as
DetNet Edge nodes. DetNet Edge nodes.
* A Track is reversible, meaning that packets can be routed against * A Track is reversible, meaning that packets can be routed against
the flow of data packets, e.g., to carry OAM measurements or the flow of data packets, e.g., to carry OAM measurements or
control messages back to the Ingress. control messages back to the Ingress.
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Southwards along a bidirectional Segment, but never bounces back. Southwards along a bidirectional Segment, but never bounces back.
2.1.4. Deterministic Networking 2.1.4. Deterministic Networking
This document reuses the terminology in section 2 of [RFC8557] and This document reuses the terminology in section 2 of [RFC8557] and
section 4.1.2 of [RFC8655] for deterministic networking and section 4.1.2 of [RFC8655] for deterministic networking and
deterministic networks. deterministic networks.
2.1.4.1. Flow 2.1.4.1. Flow
A collection of consecutive packets that must be placed on the same A collection of consecutive IP packets defined by the upper layers
Track to receive an equivalent treatment from Ingress to Egress and signaled by the same 5 or 6-tuple, see section 5.1 of [RFC8939].
within the Track. Multiple flows may be transported along the same Packets of the same flow must be placed on the same Track to receive
Track. The subTrack that is selected for the flow may change over an equivalent treatment from Ingress to Egress within the Track.
time under the control of the PSE. Multiple flows may be transported along the same Track. The subTrack
that is selected for the flow may change over time under the control
of the PSE.
2.1.4.2. Deterministic Flow Identifier (L2) 2.1.4.2. Deterministic Flow Identifier (L2)
A tuple identified by a stream_handle, and provided by a bridge, in A tuple identified by a stream_handle, and provided by a bridge, in
accordance with IEEE 802.1CB. The tuple comprises at least src MAC, accordance with IEEE 802.1CB. The tuple comprises at least src MAC,
dst MAC, VLAN ID, and L2 priority. Continuous streams are dst MAC, VLAN ID, and L2 priority. Continuous streams are
characterized by bandwidth and max packet size; scheduled streams are characterized by bandwidth and max packet size; scheduled streams are
characterized by a repeating pattern of timed transmissions. characterized by a repeating pattern of timed transmissions.
2.1.4.3. Deterministic Flow Identifier (L3) 2.1.4.3. Deterministic Flow Identifier (L3)
See section 3.3 of [DetNet-DP]. The classical IP 5-tuple that See section 3.3 of [DetNet-DP]. The classical IP 5-tuple that
identifies a flow comprises the src IP, dst IP, src port, dest port, identifies a flow comprises the src IP, dst IP, src port, dest port,
and the upper layer protocol (ULP). DetNet uses a 6-tuple where the 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 extra field is the DSCP field in the packet. The IPv6 flow label is
not used. for that purpose. not used for that purpose.
2.1.4.4. 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].
2.1.5. Reliability and Availability 2.1.5. Reliability and Availability
In the context of the RAW work, Reliability and Availability are In the context of the RAW work, Reliability and Availability are
defined as follows: defined as follows:
2.1.5.1. Service Level Agreement 2.1.5.1. Service Level Agreement
In the context of RAW, an SLA (service level agreement) is a contract In the context of RAW, an SLA (service level agreement) is a contract
between a provider, the network, and a client, the application flow, between a provider, the network, and a client, the application flow,
about measurable metrics such as latency boundaries, consecutive about measurable metrics such as latency boundaries, consecutive
losses, and packet delivery ratio (PDR). losses, and packet delivery ratio (PDR).
2.1.5.2. Service Level Objective 2.1.5.2. Service Level Objective
A service level objective (SLO) is one term in the SLO, for which A service level objective (SLO) is one term in the SLA, for which
specific network setting and operations are implemented. For specific network setting and operations are implemented. For
instance, a dynamic tuning of the packet redundancy will address an instance, a dynamic tuning of the packet redundancy will address an
SLO of consecutive losses in a row by augmenting the chances of SLO of consecutive losses in a row by augmenting the chances of
delivery of a packet that follows a loss.). delivery of a packet that follows a loss.).
2.1.5.3. Service Level Indicator 2.1.5.3. Service Level Indicator
A service level indicator (SLI) measures the complience of an SLO to A service level indicator (SLI) measures the compliance of an SLO to
the terms of the contrast. It can be for instance the statistics of the terms of the contrast. It can be for instance the statistics of
individual losses and losses in a row as time series.). individual losses and losses in a row as time series.).
2.1.5.4. Reliability 2.1.5.4. Reliability
Reliability is a measure of the probability that an item will perform Reliability is a measure of the probability that an item will perform
its intended function for a specified interval under stated its intended function for a specified interval under stated
conditions (SLA). RAW expresses reliability in terms of Mean Time conditions (SLA). RAW expresses reliability in terms of Mean Time
Between Failure (MTBF) and Maximum Consecutive Failures (MCF). More Between Failure (MTBF) and Maximum Consecutive Failures (MCF). More
in [NASA].). in [NASA].).
skipping to change at page 11, line 43 skipping to change at page 12, line 4
begins. In the context of RAW, RT is useful for a transit node, not begins. In the context of RAW, RT is useful for a transit node, not
ingress or egress. ingress or egress.
2.1.6.7. Additional References 2.1.6.7. Additional References
[DetNet-OAM] provides additional terminology related to OAM in the [DetNet-OAM] provides additional terminology related to OAM in the
context of DetNet and by extension of RAW, whereas [RFC7799] defines context of DetNet and by extension of RAW, whereas [RFC7799] defines
the Active, Passive, and Hybrid OAM methods. the Active, Passive, and Hybrid OAM methods.
2.2. Reliability and Availability 2.2. Reliability and Availability
2.2.1. High Availability Engineering Principles 2.2.1. High Availability Engineering Principles
The reliability criteria of a critical system pervade through its The reliability criteria of a critical system pervades through its
elements, and if the system comprises a data network then the data elements, and if the system comprises a data network then the data
network is also subject to the inherited reliability and availability network is also subject to the inherited reliability and availability
criteria. It is only natural to consider the art of high criteria. It is only natural to consider the art of high
availability engineering and apply it to wireless communications in availability engineering and apply it to wireless communications in
the context of RAW. the context of RAW.
There are three principles [pillars] of high availability There are three principles [pillars] of high availability
engineering: engineering:
1. elimination of single points of failure 1. elimination of single points of failure
skipping to change at page 12, line 39 skipping to change at page 12, line 47
the same fate if the bundle is cut. The same effect can happen with the same fate if the bundle is cut. The same effect can happen with
virtual links that end up in a same physical transport through the virtual links that end up in a same physical transport through the
games of encapsulation. In a same fashion, an interferer or an games of encapsulation. In a same fashion, an interferer or an
obstacle may affect multiple wireless transmissions at the same time, obstacle may affect multiple wireless transmissions at the same time,
even between different sets of peers. even between different sets of peers.
Intermediate network Nodes such as routers, switches and APs, wire Intermediate network Nodes such as routers, switches and APs, wire
bundles and the air medium itself can become single points of bundles and the air medium itself can become single points of
failure. For High Availability, it is thus required to use failure. For High Availability, it is thus required to use
physically link- and Node-disjoint paths; in the wireless space, it physically link- and Node-disjoint paths; in the wireless space, it
is also required to use the highest possible degree of diversity in is also required to use the highest possible degree of diversity
the transmissions over the air to combat the additional causes of (time, space, code, frequency, channel width) in the transmissions
transmission loss. over the air to combat the additional causes of transmission loss.
From an economics standpoint, executing this principle properly From an economics standpoint, executing this principle properly
generally increases capitalization expense because of the redundant generally increases capitalization expense because of the redundant
equipment. In a constrained network where the waste of energy and equipment. In a constrained network where the waste of energy and
bandwidth should be minimized, an excessive use of redundant links bandwidth should be minimized, an excessive use of redundant links
must be avoided; for RAW this means that the extra bandwidth must be must be avoided; for RAW this means that the extra bandwidth must be
used wisely and with parcimony. used wisely and with parcimony.
2.2.1.2. Reliable Crossover 2.2.1.2. Reliable Crossover
skipping to change at page 14, line 15 skipping to change at page 14, line 19
"Overview and Principles of Internet Traffic Engineering" [TE] "Overview and Principles of Internet Traffic Engineering" [TE]
discusses the importance of measurement for network protection, and discusses the importance of measurement for network protection, and
provides abstract an method for network survivability with the provides abstract an method for network survivability with the
analysis of a traffic matrix as observed by SNMP, probing techniques, analysis of a traffic matrix as observed by SNMP, probing techniques,
FTP, IGP link state advertisements, and more. FTP, IGP link state advertisements, and more.
Those measurements are needed in the context of RAW to inform the Those measurements are needed in the context of RAW to inform the
controller and make the long term reactive decision to rebuild a controller and make the long term reactive decision to rebuild a
complex path. But RAW itself operates in the Network Plane at a complex path. But RAW itself operates in the Network Plane at a
faster time scale. To act on the Data Plane, RAW needs live faster time scale. To act on the Data Plane, RAW needs live
information from the Operational Plane , e.g., using Bidirectional information from the Operational Plane , e.g., using Dynamic Link
Forwarding Detection [BFD] and its variants (bidirectional and remote Exchange Protocol (DLEP) [DLEP] to obtain timely and accurate
BFD) to protect a link, and OAM techniques to protect a path. knowledge of the characteristics of the link (speed, state, etc.).
2.2.2. Applying Reliability Concepts to Networking 2.2.2. Applying Reliability Concepts to Networking
The terms Reliability and Availability are defined for use in RAW in The terms Reliability and Availability are defined for use in RAW in
Section 2.1 and the reader is invited to read [NASA] for more details Section 2.1 and the reader is invited to read [NASA] for more details
on the general definition of Reliability. Practically speaking a on the general definition of Reliability. Practically speaking a
number of nines is often used to indicate the reliability of a data 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 link, e.g., 5 nines indicate a Packet Delivery Ratio (PDR) of
99.999%. 99.999%.
skipping to change at page 15, line 32 skipping to change at page 15, line 35
a reflection on a physical structure (echo). The reflections take a reflection on a physical structure (echo). The reflections take
a longer path and are delayed by the extra distance divided by the a longer path and are delayed by the extra distance divided by the
speed of light in the medium. Depending on the frequency, the speed of light in the medium. Depending on the frequency, the
echo lands with a different phase which may add up to echo lands with a different phase which may add up to
(constructive interference) or cancel the direct signal (constructive interference) or cancel the direct signal
(destructive interference). (destructive interference).
The affected frequencies depend on the relative position of the The affected frequencies depend on the relative position of the
sender, the receiver, and all the reflecting objects in the sender, the receiver, and all the reflecting objects in the
environment. A given hop will suffer from multipath fading for environment. A given hop will suffer from multipath fading for
multiple packets in a row till the something moves that changes multiple packets in a row till a phyqical movement changes the
the reflection patterns. reflection patterns.
Co-channel Interference Energy in the spectrum used for the Co-channel Interference Energy in the spectrum used for the
transmission confuses the receiver. transmission confuses the receiver.
The wireless medium itself is a Shared Risk Link Group (SRLG) for The wireless medium itself is a Shared Risk Link Group (SRLG) for
nearby users of the same spectrum, as an interference may affect nearby users of the same spectrum, as an interference may affect
multiple co-channel transmissions between different peers within multiple co-channel transmissions between different peers within
the interference domain of the interferer, possibly even when they the interference domain of the interferer, possibly even when they
use different technologies. use different technologies.
skipping to change at page 18, line 24 skipping to change at page 18, line 24
3. The RAW Conceptual Model 3. The RAW Conceptual Model
RAW inherits the conceptual model described in section 4 of the RAW inherits the conceptual model described in section 4 of the
DetNet Architecture [RFC8655]. RAW extends the DetNet service layer DetNet Architecture [RFC8655]. RAW extends the DetNet service layer
to provide additional agility against transmission loss. to provide additional agility against transmission loss.
A RAW Network Plane may be strict or loose, depending on whether RAW A RAW Network Plane may be strict or loose, depending on whether RAW
observes and takes actions on all hops or not. For instance, the observes and takes actions on all hops or not. For instance, the
packets between two wireless entities may be relayed over a wired packets between two wireless entities may be relayed over a wired
infrastructure such as a Wi-Fi extended service set (ESS) or a 5G infrastructure such as a Wi-Fi extended service set (ESS) or a 5G
Core; in that case, RAW observes and control the transmission over Core; in that case, RAW observes and controls the transmission over
the wireless first and last hops, as well as end-to-end metrics such the wireless first and last hops, as well as end-to-end metrics such
as latency, jitter, and delivery ratio. This operation is loose as latency, jitter, and delivery ratio. This operation is loose
since the structure and properties of the wired infrastructure are since the structure and properties of the wired infrastructure are
ignored, and may be either controlled by other means such as DetNet/ ignored, and may be either controlled by other means such as DetNet/
TSN, or neglected in the face of the wireless hops. TSN, or neglected in the face of the wireless hops.
A Controller Plane Function (CPF) called the Path Computation Element A Controller Plane Function (CPF) called the Path Computation Element
(PCE) [RFC4655] interacts with RAW Nodes over a Southbound API. The (PCE) [RFC4655] interacts with RAW Nodes over a Southbound API. The
RAW Nodes are DetNet relays that are capable of additional diversity RAW Nodes are DetNet relays that are capable of additional diversity
mechanisms and measurement functions related to the radio interface, mechanisms and measurement functions related to the radio interface,
skipping to change at page 19, line 27 skipping to change at page 19, line 27
Node z-- Node --- ( Nodes ) Node Node z-- Node --- ( Nodes ) Node
... . ... .
--z wireless wired --z wireless wired
z-- link --- link z-- link --- link
Figure 2: RAW Nodes Figure 2: RAW Nodes
The Link-Layer metrics are reported to the PCE in a time-aggregated, The Link-Layer metrics are reported to the PCE in a time-aggregated,
e.g., statistical fashion. Example Link-Layer metrics include e.g., statistical fashion. Example Link-Layer metrics include
typical Link bandwidth (the medium speed depends dynamically on the typical Link bandwidth (the medium speed depends dynamically on the
PHY mode and the number of users sharing the spectrum) and average PHY mode), number of flows (bandwidth that can be reserved for a
and mean squared deviation of availability and reliability figures flomw depends on the number and size of flows sharing the spectrum)
such as Packet Delivery Ratio (PDR) over long periods of time. and average and mean squared deviation of availability and
reliability figures such as Packet Delivery Ratio (PDR) over long
periods of time.
Based on those metrics, the PCE installs the Track with enough Based on those metrics, the PCE installs the Track with enough
redundant forwarding solutions to ensure that the Network Plane can redundant forwarding solutions to ensure that the Network Plane can
reliably deliver the packets within a System Level Agreement (SLA) reliably deliver the packets within a System Level Agreement (SLA)
associated to the flows that it transports. The SLA defines end-to- associated to the flows that it transports. The SLA defines end-to-
end reliability and availability requirements, where reliability may end reliability and availability requirements, where reliability may
be expressed as a successful delivery in order and within a bounded be expressed as a successful delivery in order and within a bounded
delay of at least one copy of a packet. delay of at least one copy of a packet.
Depending on the use case and the SLA, the Track may comprise non-RAW Depending on the use case and the SLA, the Track may comprise non-RAW
skipping to change at page 20, line 13 skipping to change at page 20, line 13
assure that the SLA can be met or have it recompute the Track if not. assure that the SLA can be met or have it recompute the Track if not.
4. The OODA Loop 4. The OODA Loop
The RAW Architecture is structured as an OODA Loop (Observe, Orient, The RAW Architecture is structured as an OODA Loop (Observe, Orient,
Decide, Act). It involves: Decide, Act). It involves:
1. Network Plane measurement protocols for Operations, 1. Network Plane measurement protocols for Operations,
Administration and Maintenance (OAM) to Observe some or all hops Administration and Maintenance (OAM) to Observe some or all hops
along a Track as well as the end-to-end packet delivery, more in along a Track as well as the end-to-end packet delivery, more in
Section 5; Section 4.1;
2. Controller plane elements to reports the links statistics to a 2. Controller plane elements to reports the links statistics to a
Path computation Element (PCE) in a centralized controller that Path computation Element (PCE) in a centralized controller that
computes and installs the Tracks and provides meta data to Orient computes and installs the Tracks and provides meta data to Orient
the routing decision, more in Section 6; the routing decision, more in Section 4.2;
3. A Runtime distributed Path Selection Engine (PSE) thar Decides 3. A Runtime distributed Path Selection Engine (PSE) thar Decides
which subTrack to use for the next packet(s) that are routed which subTrack to use for the next packet(s) that are routed
along the Track, more in Section 7; along the Track, more in Section 4.3;
4. Packet (hybrid) ARQ, Replication, Elimination and Ordering 4. Packet (hybrid) ARQ, Replication, Elimination and Ordering
Dataplane actions that operate at the DetNet Service Layer to Dataplane actions that operate at the DetNet Service Layer to
increase the reliability o fthe end-to-end transmission. The RAW increase the reliability o fthe end-to-end transmission. The RAW
architecture also covers in-situ signalling when the decision is architecture also covers in-situ signalling when the decision is
Acted by a node that down the Track from the PSE, more in Acted by a node that down the Track from the PSE, more in
Section 8. Section 4.4.
+-------> Orient (PCE) --------+ +-------> Orient (PCE) --------+
| link stats, | | link stats, |
| pre-trained model | | pre-trained model |
| ... | | ... |
| | | |
| v | v
Observe (OAM) Decide (PSE) Observe (OAM) Decide (PSE)
^ | ^ |
| | | |
skipping to change at page 21, line 5 skipping to change at page 21, line 5
At DetNet At DetNet
Service sublayer Service sublayer
Figure 3: The RAW OODA Loop Figure 3: The RAW OODA Loop
The overall OODA Loop optimizes the use of redundancy to achieve the The overall OODA Loop optimizes the use of redundancy to achieve the
required reliability and availability Service Level Agreement (SLA) required reliability and availability Service Level Agreement (SLA)
while minimizing the use of constrained resources such as spectrum while minimizing the use of constrained resources such as spectrum
and battery. and battery.
5. Observe: The RAW OAM 4.1. Observe: The RAW OAM
RAW In-situ OAM operation in the Network Plane may observe either a RAW In-situ OAM operation in the Network Plane may observe either a
full Track or subTracks that are being used at this time. Active RAW full Track or subTracks that are being used at this time. As packets
OAM may be needed to observe the unused segments and evaluate the may be load balanced, replicated, eliminated, and / or fragmented for
desirability of a rerouting decision. Finally, the RAW Service Layer Network Coding (NC) forward error correction (FEC), the RAW In-situ
Assurance may observe the individual PAREO operation of a relay node operation needs to be able to signal which operation occured to an
to ensure that it is conforming; this might require injecting an OAM individual packet.
packet at an upstream point inside the Track and extracting that
packet at another point downstream before it reaches the egress. Active RAW OAM may be needed to observe the unused segments and
evaluate the desirability of a rerouting decision.
Finally, the RAW Service Layer Assurance may observe the individual
PAREO operation of a relay node to ensure that it is conforming; this
might require injecting an OAM packet at an upstream point inside the
Track and extracting that packet at another point downstream before
it reaches the egress.
This observation feeds the RAW PSE that makes the decision on which This observation feeds the RAW PSE that makes the decision on which
PAREO function in actioned at which RAW Node, for one a small PAREO function is actioned at which RAW Node, for one a small
continuous series of packets. continuous series of packets.
... .. ... ..
RAN 1 ----- ... .. ... RAN 1 ----- ... .. ...
/ . .. .... / . .. ....
+-------+ / . .. .... +------+ +-------+ / . .. .... +------+
|Ingress|- . ..... |Egress| |Ingress|- . ..... |Egress|
| End |------ RAN 2 -- . Internet ....---| End | | End |------ RAN 2 -- . Internet ....---| End |
|System |- .. ..... |System| |System |- .. ..... |System|
+-------+ \ . ...... +------+ +-------+ \ . ...... +------+
skipping to change at page 22, line 14 skipping to change at page 22, line 14
The Links that are not observed by OAM are opaque to it, meaning that 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, the OAM information is carried across and possibly echoed as data,
but there is no information capture in intermediate nodes. In the but there is no information capture in intermediate nodes. In the
example above, the Internet is opaque and not controlled by RAW; example above, the Internet is opaque and not controlled by RAW;
still the RAW OAM measures the end-to-end latency and delivery ratio still the RAW OAM measures the end-to-end latency and delivery ratio
for packets sent via each if RAN 1, RAN 2 and RAN 3, and determines for packets sent via each if RAN 1, RAN 2 and RAN 3, and determines
whether a packet should be sent over either or a collection of those whether a packet should be sent over either or a collection of those
access links. access links.
6. Orient: The Path Computation Engine 4.2. Orient: The Path Computation Engine
RAW separates the path computation time scale at which a complex path RAW separates the path computation time scale at which a complex path
is recomputed from the path selection time scale at which the is recomputed from the path selection time scale at which the
forwarding decision is taken for one or a few packets (see in forwarding decision is taken for one or a few packets (see in
Section 2.3). Section 2.3).
The path computation is out of scope, but RAW expects that the The path computation is out of scope, but RAW expects that the
Controller plane protocol that installs the Track also provides Controller plane protocol that installs the Track also provides
related knowledge in the form of meta data about the links, segments related knowledge in the form of meta data about the links, segments
and possible subTracks. That meta data can be a pre-digested and possible subTracks. That meta data can be a pre-digested
skipping to change at page 22, line 44 skipping to change at page 22, line 44
* Link Quality Statistics and their projected evolution * Link Quality Statistics and their projected evolution
The Track is installed with measurable objectives that are computed The Track is installed with measurable objectives that are computed
by the PCE to achieve the RAW SLA. The objectives can be expressed by the PCE to achieve the RAW SLA. The objectives can be expressed
as any of maximum number of packet lost in a row, bounded latency, as any of maximum number of packet lost in a row, bounded latency,
maximal jitter, maximum nmuber of interleaved out of order packets, maximal jitter, maximum nmuber of interleaved out of order packets,
average number of copies received at the elimination point, and average number of copies received at the elimination point, and
maximal delay between the first and the last received copy of the maximal delay between the first and the last received copy of the
same packet. same packet.
7. Decide: The Path Selection Engine 4.3. Decide: The Path Selection Engine
The RAW OODA Loop operates at the path selection time scale to The RAW OODA Loop operates at the path selection time scale to
provide agility vs. the brute force approach of flooding the whole provide agility vs. the brute force approach of flooding the whole
Track. The OODA Loop controls, within the redundant solutions that Track. The OODA Loop controls, within the redundant solutions that
are proposed by the PCE, which will be used for each packet to are proposed by the PCE, which will be used for each packet to
provide a Reliable and Available service while minimizing the waste provide a Reliable and Available service while minimizing the waste
of constrained resources. of constrained resources.
To that effect, RAW defines the Path Selection Engine (PSE) that is To that effect, RAW defines the Path Selection Engine (PSE) that is
the counterpart of the PCE to perform rapid local adjustments of the the counterpart of the PCE to perform rapid local adjustments of the
forwarding tables within the diversity that the PCE has selected for forwarding tables within the diversity that the PCE has selected for
the Track. The PSE enables to exploit the richer forwarding the Track. The PSE enables to exploit the richer forwarding
capabilities with PAREO and scheduled transmissions at a faster time capabilities with PAREO and scheduled transmissions at a faster time
scale over the smaller domain that is the Track, in either a loose or scale over the smaller domain that is the Track, in either a loose or
a strict fashion. a strict fashion.
Compared to the PCE, the PSE operates on metrics that evolve faster, Compared to the PCE, the PSE operates on metrics that evolve faster,
but that needs to be advertised at a fast rate but only locally, but that need to be advertised at a fast rate but only locally,
within the Track. The forwarding decision may also change rapidly, within the Track. The forwarding decision may also change rapidly,
but with a scope that is also contained within the Track, with no but with a scope that is also contained within the Track, with no
visibility to the other Tracks and flows in the network. This is as visibility to the other Tracks and flows in the network. This is as
opposed to the PCE that needs to observe the whole network, and opposed to the PCE that must observe the whole network and optimize
optimize all the Tracks globally, which can only be done at a slow all the Tracks globally, which can only be done at a slow pace and
pace and using long-term statistical metrics, as presented in using long-term statistical metrics, as presented in Table 1.
Table 1.
+===============+========================+===================+ +===============+========================+===================+
| | PCE (Not in Scope) | PSE (In Scope) | | | PCE (Not in Scope) | PSE (In Scope) |
+===============+========================+===================+ +===============+========================+===================+
| Operation | Centralized | Source-Routed or | | Operation | Centralized | Source-Routed or |
| | | Distributed | | | | Distributed |
+---------------+------------------------+-------------------+ +---------------+------------------------+-------------------+
| Communication | Slow, expensive | Fast, local | | Communication | Slow, expensive | Fast, local |
+---------------+------------------------+-------------------+ +---------------+------------------------+-------------------+
| Time Scale | hours and above | seconds and below | | Time Scale | hours and above | seconds and below |
skipping to change at page 24, line 27 skipping to change at page 24, line 27
| and Forward | metrics about Links | OAM packets | | and Forward | metrics about Links | OAM packets |
+..........v..........+..........^..........+.........^.v.........+ +..........v..........+..........^..........+.........^.v.........+
| Lower layers | | Lower layers |
+..........v.....................^....................^.v.........+ +..........v.....................^....................^.v.........+
frame | sent Frame | L2 Ack oOAM | | packet frame | sent Frame | L2 Ack oOAM | | packet
over | wireless In | In | | and out over | wireless In | In | | and out
v | | v v | | v
Figure 5: PSE Figure 5: PSE
8. Act: The PAREO Functions 4.4. Act: The PAREO Functions
RAW may control whether and how to use packet replication and RAW may control whether and how to use packet replication and
elimination (PRE), Automatic Repeat reQuest (ARQ), Hybrid ARQ (HARQ) elimination (PRE), Automatic Repeat reQuest (ARQ), Hybrid ARQ (HARQ)
that includes Forward Error Correction (FEC) and coding, and other that includes Forward Error Correction (FEC) and coding, and other
wireless-specific techniques such as overhearing and constructive wireless-specific techniques such as overhearing and constructive
interferences, in order to increase the reliabiility and availability interferences, in order to increase the reliabiility and availability
of the end-to-end transmission. of the end-to-end transmission.
Collectively, those function are called PAREO for Packet (hybrid) Collectively, those function are called PAREO for Packet (hybrid)
ARQ, Replication, Elimination and Ordering. By tuning dynamically ARQ, Replication, Elimination and Ordering. By tuning dynamically
the use of PAREO functions, RAW avoids the waste of critical the use of PAREO functions, RAW avoids the waste of critical
resources such as spectrum and energy while providing that the resources such as spectrum and energy while providing that the
guaranteed SLA, e.g., by adding redundancy only when a spike of loss guaranteed SLA, e.g., by adding redundancy only when a spike of loss
is observed. is observed.
In a nutshell, PAREO establishes several paths in a network to In a nutshell, PAREO establishes several paths in a network to
provide redundancy and parallel transmissions to bound the end-to-end provide redundancy and parallel transmissions to bound the end-to-end
delay to traverse the network. Optionally, promiscuous listening delay to traverse the network. Optionally, promiscuous listening
between paths is possible, such that the Nodes on one path may between paths is possible, such that the Nodes on one path may
overhear transmissions along the other path. Considering the overhear transmissions along the other path. Considering the
scenario shown in Figure 6, many different paths are possible for to scenario shown in Figure 6, many different paths are possible to
traverse the network from ingress to egress. A simple way to benefit traverse the network from ingress to egress. A simple way to benefit
from this topology could be to use the two independent paths via from this topology could be to use the two independent paths via
Nodes A, C, E and via B, D, F. But more complex paths are possible Nodes A, C, E and via B, D, F. But more complex paths are possible
by interleaving transmissions from the lower level of the path to the by interleaving transmissions from the lower level of the path to the
upper level. upper level.
(A) -- (C) -- (E) (A) -- (C) -- (E)
/ \ / \
Ingress = | | | = Egress Ingress = | | | = Egress
\ / \ /
skipping to change at page 25, line 42 skipping to change at page 25, line 42
already received that particular frame at an earlier timeslot in a already received that particular frame at an earlier timeslot in a
dedicated transmission towards B. dedicated transmission towards B.
The PAREO model can be implemented in both centralized and The PAREO model can be implemented in both centralized and
distributed scheduling approaches. In the centralized approach, a distributed scheduling approaches. In the centralized approach, a
Path Computation Element (PCE) scheduler calculates a Track and Path Computation Element (PCE) scheduler calculates a Track and
schedules the communication. In the distributed approach, the Track schedules the communication. In the distributed approach, the Track
is computed within the network, and signaled in the packets, e.g., is computed within the network, and signaled in the packets, e.g.,
using BIER-TE, Segment Routing, or a Source Routing Header. using BIER-TE, Segment Routing, or a Source Routing Header.
8.1. Packet Replication 4.4.1. Packet Replication
By employing a Packet Replication procedure, a Node forwards a copy By employing a Packet Replication procedure, a Node forwards a copy
of each data packet to more than one successor. To do so, each Node of each data packet to more than one successor. To do so, each Node
(i.e., Ingress and intermediate Node) sends the data packet multiple (i.e., Ingress and intermediate Node) sends the data packet multiple
times as separate unicast transmissions. For instance, in Figure 7, times as separate unicast transmissions. For instance, in Figure 7,
the Ingress Node is transmitting the packet to both successors, nodes the Ingress Node is transmitting the packet to both successors, nodes
A and B, at two different times. A and B, at two different times.
===> (A) => (C) => (E) === ===> (A) => (C) => (E) ===
// \\// \\// \\ // \\// \\// \\
skipping to change at page 26, line 26 skipping to change at page 26, line 26
+=========+======+======+======+======+======+======+======+ +=========+======+======+======+======+======+======+======+
| Channel | 0 | 1 | 2 | 3 | 4 | 5 | 6 | | Channel | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
+=========+======+======+======+======+======+======+======+ +=========+======+======+======+======+======+======+======+
| 0 | S->A | S->B | B->C | B->D | C->F | E->R | F->R | | 0 | S->A | S->B | B->C | B->D | C->F | E->R | F->R |
+---------+------+------+------+------+------+------+------+ +---------+------+------+------+------+------+------+------+
| 1 | | A->C | A->D | C->E | D->E | D->F | | | 1 | | A->C | A->D | C->E | D->E | D->F | |
+---------+------+------+------+------+------+------+------+ +---------+------+------+------+------+------+------+------+
Table 2: Packet Replication: Sample schedule Table 2: Packet Replication: Sample schedule
8.2. Packet Elimination 4.4.2. Packet Elimination
The replication operation increases the traffic load in the network, The replication operation increases the traffic load in the network,
due to packet duplications. This may occur at several stages inside due to packet duplications. This may occur at several stages inside
the Track, and to avoid an explosion of the number of copies, a the Track, and to avoid an explosion of the number of copies, a
Packet Elimination procedure must be applied as well. To this aim, Packet Elimination procedure must be applied as well. To this aim,
once a Node receives the first copy of a data packet, it discards the once a Node receives the first copy of a data packet, it discards the
subsequent copies. subsequent copies.
The logical functions of Replication and Elimination may be The logical functions of Replication and Elimination may be
collocated in an intermediate Node, the Node first eliminating the collocated in an intermediate Node, the Node first eliminating the
redundant copies and then sending the packet exactly once to each of redundant copies and then sending the packet exactly once to each of
the selected successors. the selected successors.
8.3. Promiscuous Overhearing 4.4.3. Promiscuous Overhearing
Considering that the wireless medium is broadcast by nature, any Considering that the wireless medium is broadcast by nature, any
neighbor of a transmitter may overhear a transmission. By employing neighbor of a transmitter may overhear a transmission. By employing
the Promiscuous Overhearing operation, the next hops have additional the Promiscuous Overhearing operation, the next hops have additional
opportunities to capture the data packets. In Figure 8, when Node A opportunities to capture the data packets. In Figure 8, when Node A
is transmitting to its DP (Node C), the AP (Node D) and its sibling is transmitting to its DP (Node C), the AP (Node D) and its sibling
(Node B) may decode this data packet as well. As a result, by (Node B) may decode this data packet as well. As a result, by
employing corellated paths, a Node may have multiple opportunities to employing corellated paths, a Node may have multiple opportunities to
receive a given data packet. receive a given data packet.
===> (A) ====> (C) ====> (E) ==== ===> (A) ====> (C) ====> (E) ====
// ^ | \\ \\ // ^ | \\ \\
Ingress | | \\ Egress Ingress | | \\ Egress
\\ | v \\ // \\ | v \\ //
===> (B) ====> (D) ====> (F) ==== ===> (B) ====> (D) ====> (F) ====
Figure 8: Unicast with Overhearing Figure 8: Unicast with Overhearing
8.4. Constructive Interference Variations on the same idea such as link-layer anycast and multicast
may also be used to reach more than one next-hop with a single frame.
4.4.4. Constructive Interference
Constructive Interference can be seen as the reverse of Promiscuous Constructive Interference can be seen as the reverse of Promiscuous
Overhearing, and refers to the case where two senders transmit the Overhearing, and refers to the case where two senders transmit the
exact same signal in a fashion that the emitted symbols add up at the exact same signal in a fashion that the emitted symbols add up at the
receiver and permit a reception that would not be possible with a receiver and permit a reception that would not be possible with a
single sender at the same PHY mode and the same power level. single sender at the same PHY mode and the same power level.
Constructive Interference was proposed on 5G, Wi-Fi7 and even tested Constructive Interference was proposed on 5G, Wi-Fi7 and even tested
on IEEE Std 802.14.5. The hard piece is to synchronize the senders on IEEE Std 802.14.5. The hard piece is to synchronize the senders
to the point that the signals are emitted at slightly different time to the point that the signals are emitted at slightly different time
to offset the difference of propagation delay that corresponds to the to offset the difference of propagation delay that corresponds to the
difference of distance of the transmitters to the receiver at the difference of distance of the transmitters to the receiver at the
speed of light to the point that the symbols are superposed long speed of light to the point that the symbols are superposed long
enough to be recognizable. enough to be recognizable.
9. Security Considerations 5. Security Considerations
RAW uses all forms of diversity including radio technology and RAW uses all forms of diversity including radio technology and
physical path to increase the reliability and availability in the physical path to increase the reliability and availability in the
face of unpredictable conditions. While this is not done face of unpredictable conditions. While this is not done
specifically to defeat an attacker, the amount of diversity used in specifically to defeat an attacker, the amount of diversity used in
RAW makes an attack harder to achieve. RAW makes an attack harder to achieve.
9.1. Forced Access 5.1. Forced Access
RAW will typically select the cheapest collection of links that RAW will typically select the cheapest collection of links that
matches the requested SLA, for instance, leverage free WI-Fi vs. paid matches the requested SLA, for instance, leverage free WI-Fi vs. paid
3GPP access. By defeating the cheap connectivity (e.g., PHY-layer 3GPP access. By defeating the cheap connectivity (e.g., PHY-layer
interference) the attacker can force an End System to use the paid interference) the attacker can force an End System to use the paid
access and increase the cost of the transmission for the user. access and increase the cost of the transmission for the user.
10. IANA Considerations 6. IANA Considerations
This document has no IANA actions. This document has no IANA actions.
11. Contributors 7. Contributors
The editor wishes to thank: The editor wishes to thank:
Xavi Vilajosana: Wireless Networks Research Lab, Universitat Oberta Xavi Vilajosana: Wireless Networks Research Lab, Universitat Oberta
de Catalunya de Catalunya
Remous-Aris Koutsiamanis: IMT Atlantique Remous-Aris Koutsiamanis: IMT Atlantique
Nicolas Montavont: IMT Atlantique Nicolas Montavont: IMT Atlantique
Rex Buddenberg: Individual contributor Rex Buddenberg: Individual contributor
Greg Mirsky: ZTE Greg Mirsky: ZTE
for their contributions to the text and ideas exposed in this for their contributions to the text and ideas exposed in this
document. document.
12. Acknowledgments 8. Acknowledgments
TBD TBD
13. References 9. References
13.1. Normative References 9.1. Normative References
[6TiSCH-ARCHI] [6TiSCH-ARCHI]
Thubert, P., Ed., "An Architecture for IPv6 over the Time- Thubert, P., Ed., "An Architecture for IPv6 over the Time-
Slotted Channel Hopping Mode of IEEE 802.15.4 (6TiSCH)", Slotted Channel Hopping Mode of IEEE 802.15.4 (6TiSCH)",
RFC 9030, DOI 10.17487/RFC9030, May 2021, RFC 9030, DOI 10.17487/RFC9030, May 2021,
<https://www.rfc-editor.org/info/rfc9030>. <https://www.rfc-editor.org/info/rfc9030>.
[INT-ARCHI] [INT-ARCHI]
Braden, R., Ed., "Requirements for Internet Hosts - Braden, R., Ed., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, Communication Layers", STD 3, RFC 1122,
skipping to change at page 29, line 10 skipping to change at page 29, line 17
Bernardos, "RAW use cases", Work in Progress, Internet- Bernardos, "RAW use cases", Work in Progress, Internet-
Draft, draft-ietf-raw-use-cases-03, 20 October 2021, Draft, draft-ietf-raw-use-cases-03, 20 October 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-raw-use- <https://datatracker.ietf.org/doc/html/draft-ietf-raw-use-
cases-03>. cases-03>.
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path [RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655, Computation Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006, DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>. <https://www.rfc-editor.org/info/rfc4655>.
[BFD] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<https://www.rfc-editor.org/info/rfc5880>.
[RFC6291] Andersson, L., van Helvoort, H., Bonica, R., Romascanu, [RFC6291] Andersson, L., van Helvoort, H., Bonica, R., Romascanu,
D., and S. Mansfield, "Guidelines for the Use of the "OAM" D., and S. Mansfield, "Guidelines for the Use of the "OAM"
Acronym in the IETF", BCP 161, RFC 6291, Acronym in the IETF", BCP 161, RFC 6291,
DOI 10.17487/RFC6291, June 2011, DOI 10.17487/RFC6291, June 2011,
<https://www.rfc-editor.org/info/rfc6291>. <https://www.rfc-editor.org/info/rfc6291>.
[RFC7799] Morton, A., "Active and Passive Metrics and Methods (with [RFC7799] Morton, A., "Active and Passive Metrics and Methods (with
Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799, Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799,
May 2016, <https://www.rfc-editor.org/info/rfc7799>. May 2016, <https://www.rfc-editor.org/info/rfc7799>.
skipping to change at page 29, line 42 skipping to change at page 29, line 45
[RFC8557] Finn, N. and P. Thubert, "Deterministic Networking Problem [RFC8557] Finn, N. and P. Thubert, "Deterministic Networking Problem
Statement", RFC 8557, DOI 10.17487/RFC8557, May 2019, Statement", RFC 8557, DOI 10.17487/RFC8557, May 2019,
<https://www.rfc-editor.org/info/rfc8557>. <https://www.rfc-editor.org/info/rfc8557>.
[RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas, [RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", RFC 8655, "Deterministic Networking Architecture", RFC 8655,
DOI 10.17487/RFC8655, October 2019, DOI 10.17487/RFC8655, October 2019,
<https://www.rfc-editor.org/info/rfc8655>. <https://www.rfc-editor.org/info/rfc8655>.
[RFC8939] Varga, B., Ed., Farkas, J., Berger, L., Fedyk, D., and S.
Bryant, "Deterministic Networking (DetNet) Data Plane:
IP", RFC 8939, DOI 10.17487/RFC8939, November 2020,
<https://www.rfc-editor.org/info/rfc8939>.
[RFC9049] Dawkins, S., Ed., "Path Aware Networking: Obstacles to [RFC9049] Dawkins, S., Ed., "Path Aware Networking: Obstacles to
Deployment (A Bestiary of Roads Not Taken)", RFC 9049, Deployment (A Bestiary of Roads Not Taken)", RFC 9049,
DOI 10.17487/RFC9049, June 2021, DOI 10.17487/RFC9049, June 2021,
<https://www.rfc-editor.org/info/rfc9049>. <https://www.rfc-editor.org/info/rfc9049>.
13.2. Informative References 9.2. Informative References
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981, DOI 10.17487/RFC0791, September 1981,
<https://www.rfc-editor.org/info/rfc791>. <https://www.rfc-editor.org/info/rfc791>.
[TE] Awduche, D., Chiu, A., Elwalid, A., Widjaja, I., and X. [TE] Awduche, D., Chiu, A., Elwalid, A., Widjaja, I., and X.
Xiao, "Overview and Principles of Internet Traffic Xiao, "Overview and Principles of Internet Traffic
Engineering", RFC 3272, DOI 10.17487/RFC3272, May 2002, Engineering", RFC 3272, DOI 10.17487/RFC3272, May 2002,
<https://www.rfc-editor.org/info/rfc3272>. <https://www.rfc-editor.org/info/rfc3272>.
skipping to change at page 30, line 36 skipping to change at page 30, line 47
So, "Remote Loop-Free Alternate (LFA) Fast Reroute (FRR)", So, "Remote Loop-Free Alternate (LFA) Fast Reroute (FRR)",
RFC 7490, DOI 10.17487/RFC7490, April 2015, RFC 7490, DOI 10.17487/RFC7490, April 2015,
<https://www.rfc-editor.org/info/rfc7490>. <https://www.rfc-editor.org/info/rfc7490>.
[DetNet-DP] [DetNet-DP]
Varga, B., Ed., Farkas, J., Berger, L., Malis, A., and S. Varga, B., Ed., Farkas, J., Berger, L., Malis, A., and S.
Bryant, "Deterministic Networking (DetNet) Data Plane Bryant, "Deterministic Networking (DetNet) Data Plane
Framework", RFC 8938, DOI 10.17487/RFC8938, November 2020, Framework", RFC 8938, DOI 10.17487/RFC8938, November 2020,
<https://www.rfc-editor.org/info/rfc8938>. <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>.
[I-D.irtf-panrg-path-properties] [I-D.irtf-panrg-path-properties]
Enghardt, T. and C. Kraehenbuehl, "A Vocabulary of Path Enghardt, T. and C. Kraehenbuehl, "A Vocabulary of Path
Properties", Work in Progress, Internet-Draft, draft-irtf- Properties", Work in Progress, Internet-Draft, draft-irtf-
panrg-path-properties-04, 25 October 2021, panrg-path-properties-04, 25 October 2021,
<https://datatracker.ietf.org/doc/html/draft-irtf-panrg- <https://datatracker.ietf.org/doc/html/draft-irtf-panrg-
path-properties-04>. path-properties-04>.
[IPoWIRELESS] [IPoWIRELESS]
Thubert, P., "IPv6 Neighbor Discovery on Wireless Thubert, P., "IPv6 Neighbor Discovery on Wireless
Networks", Work in Progress, Internet-Draft, draft- Networks", Work in Progress, Internet-Draft, draft-
thubert-6man-ipv6-over-wireless-10, 18 November 2021, thubert-6man-ipv6-over-wireless-11, 15 December 2021,
<https://datatracker.ietf.org/doc/html/draft-thubert-6man- <https://datatracker.ietf.org/doc/html/draft-thubert-6man-
ipv6-over-wireless-10>. ipv6-over-wireless-11>.
[DetNet-OAM] [DetNet-OAM]
Mirsky, G., Theoleyre, F., Papadopoulos, G. Z., Bernardos, Mirsky, G., Theoleyre, F., Papadopoulos, G. Z., Bernardos,
C. J., Varga, B., and J. Farkas, "Framework of Operations, C. J., Varga, B., and J. Farkas, "Framework of Operations,
Administration and Maintenance (OAM) for Deterministic Administration and Maintenance (OAM) for Deterministic
Networking (DetNet)", Work in Progress, Internet-Draft, Networking (DetNet)", Work in Progress, Internet-Draft,
draft-ietf-detnet-oam-framework-05, 14 October 2021, draft-ietf-detnet-oam-framework-05, 14 October 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-detnet- <https://datatracker.ietf.org/doc/html/draft-ietf-detnet-
oam-framework-05>. oam-framework-05>.
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