text:
Der Wachsblumenstrauß (Originaltitel: Murder at the Gallop) ist ein englischer Kriminalfilm aus dem Jahr 1963, der lose auf dem Kriminalroman Der Wachsblumenstrauß (After the Funeral) von Agatha Christie basiert.

Handlung
Als sie Geld für einen guten Zweck sammeln wollen, kommen Miss Marple und der Bibliothekar Mr. Stringer beim Herrenhaus Hilfield Castle des schwerreichen Einsiedlers Mr. Enderby vorbei, nur um mitzuerleben, wie dieser die Treppe hinunterstürzt und verstirbt. Als Miss Marple sich daraufhin umsehen will, findet sie nur einen Lehmbrocken mit einem Schuhabdruck vor sowie eine Katze, vor der – wie vor allen Katzen – Mr. Enderby, wie allseits bekannt war, eine Todesangst hatte. Sie vermutet, dass diese absichtlich dort platziert wurde und es sich dementsprechend um Mord handelt, doch der Arzt stellt einen natürlichen Tod fest, und so schenkt Inspektor Craddock ihren Vermutungen keinen Glauben.

Unterstützt durch Mr. Stringer nimmt Miss Marple daher selbst Ermittlungen auf und belauscht heimlich die Testamentseröffnung, bei der das große Erbe des alten Enderby von über 100.000 Pfund auf seine Erben aufgeteilt werden soll. Überraschend bestätigt dessen Schwester, Cora Lansquenet, ihren Verdacht, indem sie ebenfalls einen Mord an dem Erblasser vermutet. Als Miss Marple ihr wenig später einen Besuch abstatten will, kommt sie allerdings schon zu spät und findet sie tot vor, erstochen mit einer Hutnadel durch die Rückenlehne ihres Stuhls.

Diesmal war es einwandfrei Mord, sodass auch Inspektor Craddock beginnt, Nachforschungen anzustellen, nicht ohne sich über Miss Marples Einmischung zu ärgern. Eine Familienzusammenkunft im Reiterhotel Gallop, das einem der Erben gehört, stellt sich als ideale Gelegenheit heraus, um die Verdächtigen festzusetzen und zu befragen. Auch Miss Marple, die als exzellente Reiterin und Eigentümerin eines seltenen Broadbeech-Damensattels von 1885 ein perfektes Alibi hat, quartiert sich ein und wird sogar vom Eigentümer Hector Enderby auf einen Reitausflug eingeladen. Immer wieder versucht sie, den gefundenen Lehmbrocken mit den Stiefeln der Verdächtigen abzugleichen, um herauszufinden, wer kurz vor dem Tod des alten Enderby noch bei diesem war. Als sie ein Gespräch der Erben belauschen kann, findet sie heraus, dass diese sich um ein potenziell wertvolles Gemälde aus dem Nachlass des Toten streiten und jeder dem anderen die Morde zutraut. Daher schrecken sie auch nicht davor zurück, die Gesellschafterin Lansquenets, Miss Milchrest, zu bedrängen, da sie sie bezichtigen, von ihrer Herrin die Identität des Mörders erfahren zu haben, was diese bestreitet. Miss Marple findet zwar heraus, dass der gefundene Lehmabdruck zum Stiefel von George Crossfield gehört, einem der Erben, dieser scheidet jedoch sofort wieder als Verdächtiger aus, da er sich mit dem tatsächlichen Mörder unterhält, der allerdings stumm bleibt. Kurz darauf wird auch er ermordet, als er sich in den Stall begibt und der Mörder von außen die Pferde aufscheucht, die Crossfield daraufhin tottrampeln. Trotz dieser Tragödie ist sich Miss Marple sicher, den Mörder ermittelt zu haben, und stellt ihm eine Falle, indem sie beim Tanzabend einen Schwächeanfall vortäuscht und sich auf ihr Zimmer zurückzieht. Ein herbeigerufener Polizeiarzt teilt den anwesenden Enderbys sowie dem Inspektor und Mr. Stringer (die beide in den Plan eingeweiht sind) mit, dass jeder Schock sich nun tödlich auswirken könnte, wodurch der anwesende Mörder gereizt wird, sie auf eine ähnliche Weise anzugreifen wie den alten Enderby. In der Nacht stattet ihr der Mörder einen Besuch ab, verkleidet als die verstorbene Cora Lansquenet, doch es handelt sich in Wahrheit um deren Bedienstete Miss Milchrest, die die beiden ersten Morde nur begangen hatte, um das wertvolle Gemälde von ihrer Herrin zu erben. Bevor sie auch Miss Marple mit einer Hutnadel erstechen kann, eilen Polizisten herein, um die Falle zuschnappen zu lassen.

Nachdem die Mörderin festgenommen und wieder Frieden eingekehrt ist, bittet Hector Enderby Miss Marple noch einmal zu sich, um ihr einen Heiratsantrag zu machen. Sie ist geschmeichelt, macht jedoch verständlich, dass sie beide zu unterschiedlich sind, woraufhin er erleichtert einsieht, dass er mit ihrer Absage noch einmal Glück hatte.

Trivia
 Der Wachsblumenstrauß ist die zweite von insgesamt vier Miss-Marple-Verfilmungen mit Margaret Rutherford in der Hauptrolle.
 Im Gegensatz zur ersten Miss-Marple-Verfilmung 16 Uhr 50 ab Paddington mit Margaret Rutherford ist die Vorlage ein Hercule-Poirot-Fall, der für den Film entsprechend adaptiert wurde.
 Der Kriminalroman wurde 1953 veröffentlicht. In den USA erschien er als Funerals Are Fatal und wurde in Großbritannien später auch unter dem Filmtitel Murder at the Gallop publiziert.
 Der deutsche Titel ist irreführend, da er von der Übersetzung der Romanvorlage übernommen wurde. Hierin liefert ein Wachsblumenstrauß Hercule Poirot den entscheidenden Hinweis zur Lösung des Falles, in der Verfilmung kommt jedoch keiner vor. Deshalb sollte der deutsche Titel ursprünglich lauten "Der Mörder sitzt am Tisch" – ein Programmheft mit diesem Titel war bereits gedruckt und Kopien damit gezogen worden, bevor er in letzter Sekunde in die Buchvariante abgeändert wurde.
 In der deutschen Synchronisation äußert Miss Marple zu Beginn des Films ihre Mordtheorie gegenüber Inspektor Craddock, indem sie ihn auf Agatha Christies Roman "Der Wachsblumenstrauß" anspricht, in dem sich ein ähnlicher Mord zugetragen haben soll. Im Originalton erwähnt sie allerdings einen Roman mit dem Titel The Ninth Life von Agatha Christie, der in der Realität nicht existiert.
 Als Miss Marple den zweiten Mord melden will, spricht sie von Murder most foul, was der Originaltitel der dritten Miss-Marple-Verfilmung ist (Deutscher Titel: Vier Frauen und ein Mord). In der deutschen Synchronisation konnte diese Anspielung nicht übernommen werden.
 Die Uraufführung des Filmes fand während der Gartenparty einer Kirche im ländlichen Cheshire statt.
 Die deutsche Fernseh-Erstausstrahlung von "Der Wachsblumenstrauß" war am 14. Februar 1970 um 20:15 Uhr im ZDF.
 Stringer Davis war mit Margaret Rutherford verheiratet.
 2005 wurde das Buch in der Fernsehserie Agatha Christie's Poirot recht werkgetreu neuverfilmt mit David Suchet in der Hauptrolle.
 Im Vorspann (01:28) ist die kleine Kirche St John the Baptist aus dem 14. Jahrhundert zu sehen, die im Ort Little Marlow steht.

Synchronisation
Die deutsche Synchronbearbeitung entstand 1963 im MGM Synchronisations-Atelier, Berlin.

Auszeichnungen
 1964 – nominiert für den "Edgar" des Edgar Allan Poe Awards als "Bester ausländischer Film".

Kritiken
 "Die köstliche Margaret Rutherford und eine Reihe netter Details machen auch diesen Agatha-Christie-Krimi zu einem zwar nicht aufregenden, aber anregenden Filmvergnügen." (Wertung: 2 Sterne = durchschnittlich) –  Lexikon "Filme im Fernsehen"

 "Die zweite Miss-Marple-Verfilmung (…) ist bereits deutlich schwächer als 16 Uhr 50 ab Paddington. Doch das schauspielerische Duell zwischen dem hochnäsig-snobistischen Robert Morley und der volkstümlichen, altjüngferlichen Margaret Rutherford bleibt allemal sehenswert. Beide verstehen es, die Spielfreude, die sie trotz der doch schon reichlich angestaubten Story zeigen, dem Zuschauer zu vermitteln." – Lexikon des Kriminalfilms

 "Der Angelpunkt des Vergnügens: Die köstliche Margaret Rutherford. Durch sie erhält das Geschehen Gemütlichkeit und einen herzhaft humoristischen Akzent, den notwendigen Grundzug des intelligent Spielerischen." – Film-Echo

 "Der Film hat Atmosphäre, Charme und Spannung, er spiegelt mit angelsächsisch-trockenem Humor eine typisch englische Welt wider." – Hamburger Abendblatt

 "Einer der besten 'Miß-Marple'-Filme." – Bernd Beckmann, Gong, München

 "Ein köstlicher britischer Krimispaß, in dem die großartige Margaret Rutherford mit dem nicht minder skurrilen Robert Morley einen glänzenden Partner zur Seite gestellt bekam. Spannung und hintergründiger Humor sind gleichermaßen wohl dosiert und machen diesen Streifen zum gelungensten Film der ganzen Serie." – Das große TV Spielfilm Filmlexikon

 "Nette bis komische und oftmals auch spannende Krimi-Unterhaltung, die sich äußerst frei an Geschichten der Krimi-Autorin Agatha Christie anlehnt. 'Der Wachsblumenstrauß' zeigt das wunderbare Darstellertrio mit Margaret Rutherford als schrullig-gewitzte Altdetektivin, Stringer Davies als ihren liebenswerten Assistenten und Charles Tingwell als Inspektor am Rande des Nervenzusammenbruchs." – Prisma (Online-Filmdatenbank)

Musik
Die Filmmusik zu den Miss-Marple-Filmen stammt von Ron Goodwin. Die Titelmelodie ist auf verschiedenen LPs und CDs erschienen. Eine Suite aus den Filmen ist auf der CD The Miss Marple Films, vorhanden.

DVD
 Miss-Marple-4-DVD-Box mit allen vier Filmen mit Margaret Rutherford (mehrere Ausgaben). In einer ersten Viererbox von Warner Home Video aus dem Jahr 2003 sind die Filme jedoch alle nicht in der Original-Breitwandversion auf den DVDs. Einzig Mörder ahoi! ist annähernd im Originalformat von 1.66:1 enthalten. In einer Neuauflage der Viererbox von Warner im Jahre 2006 sind die Filme digital überarbeitet und dieses Mal – abweichend von der Angabe auf der Verpackung – im Format von 1,78:1. Der Unterschied zwischen den beiden Auflagen liegt darin, dass das Bild der Erstausgabe (und der vorangegangenen Fernsehausstrahlungen) seitlich beschnitten ist, dafür am oberen und unteren Bildrand mehr Informationen enthält (was auf eine Open-Matte-Version hinzuweisen scheint), während das Bild der Neuauflage am oberen und unteren Bildrand beschnitten ist, dafür an den Seiten mehr Bildinformationen bietet. Beide Versionen weichen also vom Originalformat ab.

Literatur
 Agatha Christie: Der Wachsblumenstrauß. Ein Hercule-Poirot-Roman (Originaltitel: After the Funeral). Deutsch von Ursula Wulfekamp. Fischer-Taschenbuchverlag, Frankfurt am Main 2004, ISBN 3-596-16539-3, 286 S.
 Georg Seeßlen: George Pollock und die britischen Miss Marple-Filme in ders.: Mord im Kino. Geschichte und Mythologie des Detektiv-Films. Rowohlt, Reinbek 1981, ISBN 3-499-17396-4
 Klaus Rödder: Die haben ihre Methoden – wir die unseren, Mr. Stringer: Dame Margaret Rutherford – Auf den Spuren von Miss Marple. Bösche Verlag, Berlin 2009, ISBN 978-3-923809-87-5

Weblinks

Einzelnachweise

Filmtitel 1963
Britischer Film
Schwarzweißfilm
Kriminalfilm
Filmkomödie
Thriller
Agatha-Christie-Verfilmung
Film über Miss Marple
Hotel im Film


text:
draft-ietf-raw-architecture-10
Reliable and Available Wireless Architecture
draft-ietf-raw-architecture-11 draft-ietf-raw-architecture-10 draft-ietf-raw-architecture-09 draft-ietf-raw-architecture-08 draft-ietf-raw-architecture-07 draft-ietf-raw-architecture-06 draft-ietf-raw-architecture-05 draft-ietf-raw-architecture-04 draft-ietf-raw-architecture-03 draft-ietf-raw-architecture-02 draft-ietf-raw-architecture-01 draft-ietf-raw-architecture-00 draft-pthubert-raw-architecture-09 draft-pthubert-raw-architecture-08 draft-pthubert-raw-architecture-07 draft-pthubert-raw-architecture-06 draft-pthubert-raw-architecture-05 draft-pthubert-raw-architecture-04 draft-pthubert-raw-architecture-03 draft-pthubert-raw-architecture-02 draft-pthubert-raw-architecture-01 draft-pthubert-raw-architecture-00 draft-ietf-raw-architecture-11 draft-ietf-raw-architecture-10 draft-ietf-raw-architecture-09 draft-ietf-raw-architecture-08 draft-ietf-raw-architecture-07 draft-ietf-raw-architecture-06 draft-ietf-raw-architecture-05 draft-ietf-raw-architecture-04 draft-ietf-raw-architecture-03 draft-ietf-raw-architecture-02 draft-ietf-raw-architecture-01 draft-ietf-raw-architecture-00 draft-pthubert-raw-architecture-09 draft-pthubert-raw-architecture-08 draft-pthubert-raw-architecture-07 draft-pthubert-raw-architecture-06 draft-pthubert-raw-architecture-05 draft-pthubert-raw-architecture-04 draft-pthubert-raw-architecture-03 draft-pthubert-raw-architecture-02 draft-pthubert-raw-architecture-01 draft-pthubert-raw-architecture-00
Pascal Thubert
draft-pthubert-raw-architecture
txt html xml pdf bibtex
Internet-Draft RAW Architecture/Framework November 2022
Thubert Expires 18 May 2023 [Page]
Workgroup:
Intended Status:
P. Thubert, Ed.
Reliable and Available Wireless (RAW) provides for high reliability and availability for IP connectivity across any combination of wired and wireless network segments. The RAW Architecture extends the DetNet Architecture and other standard IETF concepts and mechanisms to adapt to the specific challenges of the wireless medium, in particular intermittently lossy connectivity. This document defines a network control loop that optimizes the use of constrained spectrum and energy while maintaining the expected connectivity properties, typically reliability and latency. The loop involves OAM, PCE, and PREOF extensions, and a new Controller plane Function called the Path Selection Engine, that dynamically selects the DetNet path for the next packets to route around local failures.¶
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 18 May 2023.¶
Copyright (c) 2022 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. 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.¶
2. Terminology
2.1.1. ARQ
2.1.2. FEC
2.1.3. HARQ
2.1.4. OAM
2.1.5. OODA
2.1.6. PAREO
2.2. Link and Direction
2.2.1. Flapping
2.2.2. Uplink
2.2.3. Downlink
2.2.4. Downstream
2.3. Path and Tracks
2.3.1. Path
2.3.2. Track
2.3.3. Segment
2.4. Deterministic Networking
2.4.1. Flow
2.4.2. Deterministic Flow Identifier (L2)
2.4.4. TSN
2.5. Reliability and Availability
2.5.1. Service Level Agreement
2.5.2. Service Level Objective
2.5.3. Service Level Indicator
2.5.4. Reliability
2.5.5. Available
2.5.6. Availability
2.6. OAM variations
2.6.1. Active OAM
2.6.2. In-Band OAM
2.6.3. Out-of-Band OAM
2.6.4. Limited OAM
2.6.5. Upstream OAM
2.6.6. Residence Time
2.6.7. Additional References
3. Reliable and Available Wireless
3.1.1. High Availability Engineering Principles
3.1.2. Applying Reliability Concepts to Networking
3.1.3. Wireless Effects Affecting Reliability
3.2. The RAW problem
4. The RAW Conceptual Model
4.1. The RAW Planes
4.2. RAW vs. Upper and Lower Layers
4.3. RAW and DetNet
5. The RAW Control Loop
5.1. Routing Time Scale vs. Forwarding Time Scale
5.2. A OODA Loop
5.3. Observe: The RAW OAM
5.4. Orient: The Path Computation Engine
5.5. Decide: The Path Selection Engine
5.6. Act: DetNet Path Selection and PAREO functions
6. Security Considerations
6.1. Layer-2 encryption
6.2. Forced Access
7. IANA Considerations
8. Contributors
9. Acknowledgments
10.1. Normative References
10.2. Informative References
Deterministic Networking is an attempt to emulate the properties of a serial link over a switched fabric, by providing a bounded latency and eliminating congestion loss, even when co-existing with best-effort traffic. It is getting traction in various industries including professional A/V, manufacturing, online gaming, and smartgrid automation, with both cost savings and complexity benefits (e.g., vs. loads of P2P cables).¶
Bringing determinism in a packet network means eliminating the statistical effects of multiplexing that result in probabilistic jitter and loss. This can be approached with a tight control of the physical resources to maintain the amount of traffic within a budgeted volume of data per unit of time that fits the physical capabilities of the underlying network, and the use of time-shared resources (bandwidth and buffers) per circuit, and/or by shaping and/or scheduling the packets at every hop.¶
This innovation was initially introduced on wired networks, with IEEE 802.1 Time Sensitive networking (TSN) - for Ethernet LANs - and IETF DetNet. But the wired and the wireless media are fundamentally different at the physical level and in the possible abstractions that can be built for IPv6 [IPv6], more in [IPoWIRELESS]. Nevertheless, deterministic capabilities are required in a number of wireless use cases as well [RAW-USE-CASES]. With new scheduled radios such as TSCH and OFDMA [RAW-TECHNOS] being developed to provide determinism over wireless links at the lower layers, providing DetNet capabilities is now becoming possible.¶
Wireless networks operate on a shared medium where uncontrolled interference, including the self-induced multipath fading cause random transmission losses. Fixed and mobile obstacles and reflectors may block or alter the signal, causing transient and unpredictable 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.¶
Reliable and Available Wireless (RAW) takes up the challenge of providing highly available and reliable end-to-end performances in a network with scheduled wireless segments. To achieve this, RAW leverages multiple links and parallel transmissions, providing enough diversity and redundancy to ensure the timely packet delivery while preserving energy and optimizing the use of the shared spectrum.¶
RAW reuses terminology defined for DetNet in the "Deterministic Networking Architecture" [RFC8655], e.g., PREOF for Packet Replication, Elimination and Ordering Functions.¶
RAW also reuses terminology defined for 6TiSCH in [6TiSCH-ARCHI] such as the term Track. A Track associates a topological graph with usage metadata that represent how the paths within the Track are used.¶
In an quantic analogy, a Track is to a path what an atomic orbital is to a planetary orbit, in that the electron has a probability of presence within a known shape as opposed to a deterministic trajectory.¶
In a herding gnous analogy, a gnou follows its own path that it marks with its hooves as it goes; before the herd starts, any point within the Track has a statistical chance to be marked by one or more hooves, meaning on path for those gnous; once the herd has passed, the Track can be observed from above, but it was there in advance as a potential that the gnous were to follow.¶
The concept of Track is agnostic to the underlaying technology and applies but is not limited to any fully or partially wireless mesh. RAW specifies strict and loose Tracks 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:¶
Automatic Repeat Request, enabling an acknowledged transmission and retries. ARQ is a typical model at Layer-2 on a wireless medium. ARQ is typically implemented hop-by-hop and not end-to-end in wireless networks. Else, it introduces excessive indetermination in latency, but a limited number of retries within a bounded time may be used within end-to-end constraints.¶
Forward Error Correction, adding redundant data to protect against a partial loss without retries.¶
Hybrid Automatic Repeat Request, combining FEC and ARQ.¶
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 Track.¶
Observe, Orient, Decide, Act. The OODA Loop is a conceptual cyclic model developed by USAF Colonel John Boyd, and that is applicable in multiple domains where agility can provide benefits against brute force.¶
Packet (hybrid) ARQ, Replication, Elimination and Ordering. PAREO is a superset Of DetNet's PREOF that includes leveraging lower-layer (typically wireless) techniques such as short range broadcast, MUMIMO, PHY rate and other Modulation Coding Scheme (MCS) adaptation, constructive interference and overhearing, separately or in combination, to increase the end-to-end reliability. PAREO functions that are actuated at the lower layers may be controlled through abstract interfaces by the RAW extensions within the DetNet Service sublayer.¶
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.¶
Connection from end-devices to a 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).¶
The reverse direction from uplink.¶
Following the direction of the flow data path along a Track.¶
Against the direction of the flow data path along a Track.¶
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 will typically traverse the same sequence of gateways. We use the term "path" for this sequence. Note that a path is uni-directional; it is not unusual to have different paths in the two directions between a given host pair.¶
Section 2 of [I-D.irtf-panrg-path-properties] 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. A path is unidirectional. Paths are time-dependent, i.e., the sequence of path elements over which packets are sent from one node to another may change. A path is defined between two nodes.¶
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 on the way from A to B, a packet from A to B experiences 2 paths, A->C->E->D->B and A->C->F->D->B. The adjectives "serial" or "simple" are used to clarify when dealing with such path.¶
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 experience 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, that experience is subject to change from a packet to the next, but all the possible experiences are all contained within a finite set. Therefore we introduce below the term of a Track that coalesces that set and covers the overall topology where the possible DetNet paths are all contained. As such, the Track coalesces all the possible paths that a flow may experience, each with its own statistical probability to be used.¶
A networking graph that can be followed to transport packets with equivalent treatment, associated with useage metadata; as opposed to the definition of a path above, a Track 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 Track is very much like a DetNet path, aggregating multiple paths that may overlap, fork and rejoin, for instance to enable a protection service by the PREOF operations.¶
+---------+
| IoT G/W |
EGR  <=== Elimination at Egress
/------/   \-------\    Wired backbone
|                  |
+--|--+            +--|--+
|  |  | Backbone   |  |  | Backbone
|  |  | Router     |  |  | Router
o   \     o          / Track branch
o      o      o---o---o   o      o   o  o
\  o /    o          o         o
o   o   \  /       o        low power lossy network
\/ o           o        o
o  IN <=== Replication at Track Ingress
o <- source device
Figure 1: Example IoT Track to an IoT gateway with 1+1 redundancy
Refining further, a Track is defined as the coalescence of the collection of all the feasible DetNet Paths that a packet which flow is assigned to the Track may be forwarded along. A packet that is assigned to the Track will experience one of the feasible DetNet Paths based on the current selection by the PSE at the time the packet traverses the network.¶
Refining even further, the feasible DetNet Paths within the Track may or may not be computed in advance, but decided upon the detection of a change from a clean slate. Furthermore, the PSE decision may be distributed, which yields a large combination of possible and dependant decisions, with no node in the network capable of reporting which is the current DetNet Path within the Track.¶
In DetNet [RFC8655] terms, a Track has the following properties:¶
A Track is a Layer-3 abstraction built upon P2P IP links between routers. A router may form multiple P2P IP links over a single radio interface.¶
A Track has one Ingress and one Egress nodes, which operate as DetNet Edge nodes.¶
The graph of a Track 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 PAREO functions.¶
The topological edges of the graph are serial sequences of DetNet Transit nodes that operate at the DetNet Forwarding sub-layer.¶
A serial path formed by a topological edge of a Track. East-West Segments are oriented from Ingress (East) to Egress (West). North/South Segments can be bidirectional; to avoid loops, measures must be taken to ensure that a given packet flows either Northwards or Southwards along a bidirectional Segment, but never bounces back.¶
This document reuses the terminology in section 2 of [RFC8557] and section 4.1.2 of [RFC8655] for deterministic networking and deterministic networks.¶
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 Track to receive an equivalent treatment from Ingress to Egress within the Track. Multiple flows may be transported along the same Track. The DetNet Path that is selected for the flow may change over time under the control of the PSE.¶
A tuple identified by a stream_handle, and provided by a bridge, in accordance with IEEE 802.1CB. The tuple comprises at least source MAC, destination MAC, VLAN ID, and L2 priority. Continuous streams are characterized by bandwidth and max packet size; scheduled streams are characterized by a repeating pattern of timed transmissions.¶
See section 3.3 of [DetNet-DP]. The classical 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.¶
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].¶
In the context of the RAW work, Reliability and Availability are defined as follows:¶
In the context of RAW, an SLA (service level agreement) is a contract between a provider, the network, and a client, the application flow, about measurable metrics such as latency boundaries, consecutive losses, and packet delivery ratio (PDR).¶
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 will address an SLO of consecutive losses in a row by augmenting the chances of delivery of a packet that follows a loss.¶
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.).¶
Reliability is a measure of the probability that an item will perform its intended function for a specified interval under stated conditions (SLA). RAW expresses reliability in terms of Mean Time Between Failure (MTBF) and Maximum Consecutive Failures (MCF). More in [NASA].).¶
That is exempt of unscheduled outage or derivation from the terms of the SLA. A basic expectation for a RAW network is that the flow is maintained in the face of any single breakage or flapping.¶
Availability is a measure of the relative amount of time where a RAW Network operates in stated condition (SLA), expressed as (uptime)/(uptime+downtime). Because a serial wireless path may not be good enough to provide the required reliability, and even 2 parallel paths may not be over a longer period of time, the RAW availability implies a journey that is a lot more complex than following a serial path.¶
See [RFC7799]. In the context of RAW, Active OAM is used to observe a particular Track, DetNet Path, or Segment of a Track regardless of whether it is used for traffic at that time.¶
An active OAM packet is considered in-band for the monitored Track when it traverses the same set of links and interfaces and if the OAM packet receives the same QoS and PAREO treatment as the packets of the data flows that are injected in the Track.¶
Out-of-band OAM is an active OAM whose path is not topologically congruent to the Track, or its test packets receive a QoS and/or PAREO treatment that is different from that of the packets of the data flows that are injected in the Track, or both.¶
An active OAM packet is a Limited OAM packet when it observes the RAW operation over a node, a segment, or a DetNet Path of the Track, though not from Ingress to Egress. It is injected in the datapath and extracted from the datapath around the particular function or subnetwork (e.g., around a relay providing a Service sublayer replication point) that is being tested.¶
An upstream OAM packet is an Out-of-Band OAM packet that traverses the Track from egress to ingress on the reverse direction, to capture and report OAM measurements upstream. The collection may capture all information along the whole Track, or it may only learn select data across all, or only a particular DetNet Path, or Segment of a Track.¶
A residence time (RT) is defined as the time period between 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.¶
[DetNet-OAM] provides additional terminology related to OAM in the context of DetNet and by extension of RAW, whereas [RFC7799] defines the Active, Passive, and Hybrid OAM methods.¶
The reliability criteria of a critical system pervades through its elements, and if the system comprises a data network 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:¶
elimination of single points of failure¶
reliable crossover¶
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.¶
3.1.1.1. 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.¶
IP Routers leverage routing protocols to compute alternate routes in case of a failure. There is a rather open-ended issue over alternate routes -- for example, when links are cabled through the same conduit, they form a shared risk link group (SRLG), and will share 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 games of 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- 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 capitalization 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 with parsimony.¶
3.1.1.2. Reliable Crossover
Having a 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 will 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, 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 guaranteed SLA 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.¶
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 will 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.¶
3.1.1.3. Prompt Notification of Failures
The execution of the two above principles is likely to render a system where the user will rarely see a failure. But someone needs to 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.¶
"An Architecture for Describing Simple Network Management Protocol (SNMP) Management Frameworks" [STD 62] describes how to use SNMP to observe and correct long-term faults.¶
"Overview and Principles of Internet Traffic Engineering" [TE] discusses the importance of measurement for network protection, and provides abstract an method for network survivability with the analysis of a traffic matrix as observed by SNMP, probing techniques, FTP, 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 complex path based on statistical and aggregated information. RAW itself operates in the 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 the Dynamic Link Exchange Protocol (DLEP) [DLEP], or transported over multiple hops using OAM and reverse OAM, as illustrated in Figure 9.¶
The terms Reliability and Availability are defined for use in RAW in Section 2 and the reader is invited to read [NASA] 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%.¶
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 frame, but does not affect the previous or next frame, nor frames 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 never be fully avoided and the systems are built to resist to one loss, e.g., using redundancy with Retries (HARQ) or Packet Replication and Elimination (PRE), 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 will not happen, IOW that the number of losses-in-a-row can be bounded. In that case, what is really desired is a Maximum Consecutive Failures (MCF). If the number of losses in a row passes the MCF, 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 or as an MTBF as a proxy to indicate an MCF, e.g., as described in section 7.4 of the "Deterministic Networking Use Cases" [RFC8578].¶
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 echo lands with a different phase which may add up to (constructive interference) or cancel the direct signal (destructive interference).¶
The affected frequencies depend on the relative position of the sender, the receiver, and all the reflecting objects in the environment. A given hop will suffer 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 optimal transmission happens when the Fresnel Zone between the sender and the receiver is free of obstacles.¶
As long as a physical object (e.g., a metallic trolley between peers) that affects the transmission is not removed, the quality of the link is affected.¶
In an environment that is rich of metallic structures and mobile objects, a single radio link will provide 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) keeps transmitting, a continuous stream of packets will be 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 will defeat short-term interferences; spatial diversity combats very local causes 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.¶
While the generic "Deterministic Networking Problem Statement" [RFC8557] applies to both the wired and the wireless media, the methods to achieve RAW must extend those used to support time-sensitive networking over wires, as a RAW solution has to address less consistent transmissions, energy conservation and shared spectrum efficiency.¶
Operating at the 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., controlling the use of diverse radio access technologies to optimize the end-to-end application experience.¶
RAW improves the DetNet services by providing elements that are specialized for transporting IP flows over deterministic radios technologies such as listed in [RAW-TECHNOS]. Conceptually, RAW is agnostic to the radio layer underneath though the capability to schedule transmissions is assumed. How the PHY is 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. Nevertheless, cross-layer optimizations may take place to ensure proper link awareness (think, link quality) and packet handling (think, scheduling).¶
The "Deterministic Networking Architecture" [RFC8655] is composed of three planes: the Application (User) Plane, the Controller Plane, and the Network Plane. The DetNet Network Plane is composed of a DetNet service sub-layer that focuses on flow protection (e.g., using redundancy) and can be fully operated at Layer-3, and a DetNet forwarding sub-layer that associates the flows to the paths, ensures the availability of the necessary resources, and leverages Layer-2 functionalities for timely delivery to the next DetNet system.¶
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 service 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 2, or diverse radio access networks as illustrated in Figure 8.¶
As opposed to wired links, the availability and performance of an individual wireless link cannot be trusted over the long term; it will vary with transient service discontinuity, and any serial path that includes wireless hops is bound to experience service discontinuity. On the other hand, the wireless medium provides unique capabilities that cannot be found on wires and that the RAW Architecture leverages opportunistically to improve the end-to-end reliability over a collection of links.¶
Those capabilities include:¶
Promiscuous Overhearing:
Because the medium is broadcast as opposed to physically point to point like a wire, 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 multipoint to multipoint progress in the orward 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 variates over time, the concept of metric must also be revisited. Shortest path loses its absolute value, and hop count turns into a bad idea as the link budget drops with the distance. Routing over radio requires both 1) a new and more dynamic sense of the link, with new protocols such as DLEP and L2-trigger to maintain L3 up to date with the link quality and availability, and 2) a new approach to multipath routing, where non-equal cost multipath becomes the norm as shortest path loses its meaning with the instability of the metrics.¶
ARQ, FEC and codes:
Though feasible on any technology, proactive (forward) and reactive (ARQ) error correction are typical to the wireless media. Bounded latency can still be obtained on a wireless link while operating those technologies, provided that the extra transmission happens within the budget allocated to that hop, or that the introduced delay is compensated along the path. In the case of coded fragments and retries, it makes sense to variate all the possible physical properties of the transmission to reduce the chances that the same effect causes the loss of both original and redundant transimissions.¶
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.¶
RAW and DetNet route application flows that require a special treatment along the paths that will provide that treatment. This may be seen as a form of Path Aware Networking and may be subject to impediments documented in [RFC9049].¶
The establishment of a path is not in-scope for RAW. It may be the product of a centralized Controller Plane Function like a Path computation Element (PCE) [RFC4655] or a distributed routing protocol. For the most part, the remainder of the document mentions centralized control and PCE, but conceptually, the same issues and needs would arise for a distributed protocol that would attempt to allocate constrained resources and optimize globally, and the distributed approach is considered in scope too.¶
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 complex path (see Section 2.3) 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.¶
RAW distinguishes the longer time scale at which routes are computed from the the shorter forwarding time scale where per-packet decisions are made. RAW Network Plane operations happen at the forwarding time scale on one DetNet flow over a complex path delineated by a Track (see Section 2.3.2). 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 just a subset of the hops are observed and controlled by RAW.¶
The RAW Architecture is based on an abstract OODA Loop (Observe, Orient, Decide, Act). The generic concept involves:¶
Network Plane measurement protocols for Operations, Administration and Maintenance (OAM) to Observe some or all hops along a Track as well as the end-to-end packet delivery¶
Optional Controller plane elements that report the links statistics to be used to compute and install the Tracks, and provides meta data to Orient the routing decision, e.g., by a PCE in a centralized controller¶
A Runtime distributed Path Selection Engine (PSE) that Decides which DetNet Path to use for the next packet(s) that are routed along the Track¶
Packet (hybrid) ARQ, Replication, Elimination and Ordering Dataplane actions that operate at the DetNet Service sublayer to increase the reliability of the end-to-end transmissions. The RAW architecture also covers in-situ signaling when the decision is Acted by a node that down the Track from the PSE.¶
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.¶
This document presents the RAW problem and associated terminology in Section 3.2, and elaborates in Section 5.2 on the OODA loop based on the RAW conceptual model presented in Section 4.¶
RAW inherits the conceptual model described in section 4 of the DetNet Architecture [RFC8655]. RAW extends the DetNet service layer to provide additional agility against transmission loss.¶
A RAW Network Plane may be strict (as illustrated in Figure 4 or loose (as illustrated in Figure 5, depending on whether RAW observes and takes actions on all hops or not. For instance, the packets between two wireless entities may be relayed over a wired infrastructure such as a Wi-Fi extended service set (ESS) or a 5G 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 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.¶
A Controller Plane Function (CPF) such as a PCE interacts with RAW Nodes over a Southbound API. The RAW Nodes are DetNet relays that are capable of additional diversity mechanisms and measurement functions related to the radio interface, in particular the PAREO diversity mechanisms. RAW leverages a CPF that operates inside the RAW Nodes (typically the Ingress Edge Nodes) to dynamically adapt the path of the packets and optimizes the resource usage.¶
The PCE defines a complex Track between an Ingress End System and an Egress End System, and indicates to the RAW Nodes where the PAREO operations may be actioned in the Network Plane. The Track may be strict, meaning that the DetNet forwarding sublayer operations are enforced end-to-end The Track may be expressed loosely to enable traversing a non-RAW subnetwork as in Figure 5. In that case, RAW can not leverage end-to-end DetNet and cannot provide latency guarantees. The non-RAW subnetwork is neglected in the RAW computation, that is, considered jitterless, and infinitely reliable and/or available in comparison with the links between RAW nodes, so loss and jitter that is measured end-to-end is attributed to the RAW hops (typically an access link).¶
CPF               CPF          CPF                 CPF
Southbound API
_-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-._-
RAW  --/   RAW  --/   RAW  --/   RAW
/-- Node  /--  Node  /--  Node  /--  Node --/
Ingress --/    /          /                           /-- Egress
End           /          /         .. .                   End
Node   ---/   /          /       .. ..  .             /-- Node
/-- RAW  --/   RAW     ( non-RAW ) -- RAW --/
Node  /--  Node --- ( Nodes  )   Node
--/   wireless           wired
/--  link           --- link
Figure 2: RAW Nodes
The Link-Layer metrics are reported to the PCE in a time-aggregated, e.g., statistical fashion. Example Link-Layer metrics include typical Link bandwidth (the medium speed depends dynamically on the PHY mode), 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 figures such as Packet Delivery Ratio (PDR) over long periods of time.¶
Based on those metrics, the PCE installs the Track with enough redundant forwarding solutions to ensure that the Network Plane can reliably deliver the packets within a System Level Agreement (SLA) associated to the flows that it transports. The SLA defines end-to-end reliability and availability requirements, where 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 Track may comprise non-RAW segments, either interleaved inside the Track, or all the way to the Egress End Node (e.g., a server in the Internet). 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 PAREO diversity schemes is actioned by which RAW Nodes.¶
Once a Track is established, per-segment and end-to-end reliability and availability statistics are periodically reported to the PCE to assure that the SLA can be met or have it recompute the Track if not.¶
RAW improves the reliability of transmissions and the availability of the communication resources, but does not provide scheduling and shaping, so RAW itself does not provide guarantees such as latency for the application payload. Rather, it should be seen as a dynamic optimization of the use of redundancy to maintain it within certain boundaries. For instance, ARQ, which is part of the PAREO capabilities (see Section 5.6) is operated by the lower layers and RAW will only abstract the concept and hint the lower layers on the desired outcome, as opposed to performing the retries at Layer-3.¶
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 sublayers and the layers below. Excess of incoming traffic at the DetNet Ingress will cause either dropping, queueing, or reclassification of the packets, and entail loss, latency, or jitter, and moot 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 the lower layers to provide the timing and physical resources guarantees that are needed to match the traffic SLA. When the availability of the physical resource varies, RAW will act on the distribution of the traffic to leverage alternates within a finite set of potential resources.¶
RAW leverages the DetNet Forwarding sub-layer and requires the support of in-situ OAM in DetNet Transit Nodes (see fig 3 of [RFC8655] for the dynamic acquisition of link capacity and state to maintain a strict RAW service, end-to-end, over a DetNet Network. RAW enhances 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.¶
RAW extends the DetNet Stack (see fig 4 of [RFC8655]) with additional functionality at the DetNet Service sub-layer for the PSE operation. Layer-3 in general and DetNet in particular operates on abstractions of the lower layers and through APIs to control those abstractions. For instance, DetNet already leverages lower layers for time-sensitive operations such as time synchronization and traffic shapers. Because the performances of the radio layers are subject to rapid changes, so RAW needs more dynamic gauges and knobs. To that effect, the DetNet PREOF is extended with the PAREO capabilities (see Section 5.6) and the RAW PAREO Actuator manages dynamically the PAREO operations, which may be performed either within the DetNet sublayers or at a lower layer, using a common radio abstraction and APIs in the latter case. In particular, PAREO needs the capability 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). The other way around RAW needs hints about the radio conditions like L2 triggers (RSSI, LQI, ETX...) over all the wireless hops. This information is useful in the controller plane for both the PCE and PSE.¶
The RAW Service sub-layer also adds the OAM Propagator that (re)generates the OAM information as it is formed and propagated In-Band or Out-of-Band. The RAW Service sub-layer may be present in DetNet Edge and Relay Nodes, though the PAREO Actuator has no operation in the Egress Edge Node.¶
RAW also adds a Control sub-layer that operates in the DetNet Controller Plane. The RAW Control sub-layer typically runs only in the DetNet Ingress Edge Node or End System, though it may also run in DetNet Relay Nodes when the RAW Control sub-layer is distributed along the Track. The RAW Control sub-layer functionality includes the PSE that decides the DetNet Path for the next packets of a flows and controls the PAREO Actuators along the DetNet Path through specific signaling, and the OAM Supervisor that triggers, and learns from, OAM observations, and feeds the PSE for its next decision.¶
+------------------------------+ +--------------------------------+
|                              | |                                |
.....................................................................
| +----------+  +------------+ | | .-.-.-.-.-.--.  .-.-.-.-.-.--. |
| | PSE      |  | OAM        | | | | Distr. PSE |  | Distr. OAM | |
| |          |  | Supervisor | | | |            |  | Supervisor | |
|                              | |    optional         optional   |
RAW Control sub-layer
DetNet Service sub-layer
| +----------+  +------------+ | | +------------+  +------------+ |
| | PAREO    |  |  OAM       | | | |  PAREO     |  |  OAM       | |
| | Actuator |  |  Observer  | | | |  Actuator  |  |  Observer  | |
DetNet Forwarding sub-layer
|               +------------+ | |                 +------------+ |
|               |In-Situ OAM | | |                 |In-Situ OAM | |
End System or                       Relay
Ingress Edge Node                     Node
Figure 3: RAW functional posture within DetNet sublayers
There are 2 main proposed models to deploy RAW and DetNet. In the first model (strict) illustrated in Figure 4, RAW operates over a continuous DetNet Service end-to-end between the Ingress and the Egress Edge Nodes or End Systems.¶
A minimal Forwarding sub-layer service is provided at all DetNet Nodes to ensure that the OAM information flows. Relay Nodes may or may not support RAW services, and the Edge nodes do support RAW. DetNet guarantees such as latency are provided end-to-end, and RAW supports the DetNet Service 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
<--------------------Full Guarantees------------------------------->
Figure 4: (Strict) RAW over DetNet
In the second model (loose), illustrated in Figure 5, 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 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).¶
+---------+            +---------+                       +---------+
| RAW +   |            | DetNet  |                       | RAW +   |
| DetNet  |            |  Only   |                       | DetNet  |
| Service |            | Service |                       | Service |
+---------+----------------------+---+               +---+---------+
|          DetNet                    |               |   DetNet    |
|         Forwarding                 |               | Forwarding  |
+------------------------------------+               +-------------+
Ingress    Transit       Relay           Internet           Egress
End  ...   Nodes   ...   Nodes    ...                ...       End
System                                                      System
<----------------------No Guarantee-------------------------------->
Figure 5: Loose RAW
With DetNet, the Controller Plane Function (CPF) handles the routing computation and maintenance. With RAW, the CPF also performs the PSE orientation, proposing DetNet Paths to use in response to network events. The CPF can be can be centralized in a PCE, and can reside outside the network. This is how the remainder of this document depicts it, though the CPF could be implemented otherwise without affecting the architecture. In a wireless mesh, the path to the PCE can be expensive and slow, possibly going across the whole mesh and back. Reaching to the PCE can also be slow in regards to the speed of events that affect the forwarding operation at the radio layer. In the same fashion, a distributed routing protocol may also take time and consume excessive wireless resources to reconverge to a new optimized state.¶
Due to that cost and latency, the Controller Plane is not expected to be sensitive/reactive to 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.¶
+----------------+
|  Controller    |
|    [PCE]       |
_-._-._-._-._-._-.  |  ._-._-._-._-._-._-._-._-._-._-._-._-
_-._-._-._-._-._-._-. | _-._-._-._-._-._-._-._-._-._-._-._-
....   |  .......
....    .  | .       .......
....          v               ...
..    A-------B-------C---D        ..
...     /  \           /      \      ..
.       I ----M-------N--***-- E        ..
..       \         /         /         ...
..      P--***--Q-----M---R        ....
..                              ....
.   <----- Fast ------->    ....
.......                ....
*** = flapping at this time
Figure 6: Time Scales
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 will cancel the line of sight transmission for a few seconds, or a radar measures the depth of a pool 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 complex Track that enables multiple Non-Equal Cost Multi-Path (N-ECMP) forwarding solutions, and leaves it to the Data Plane to make the per-packet decision of which of these possibilities should be used.¶
In the wired world, and more specifically 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 MPLS-TP or BFD over a collection of SD-WAN tunnels. RAW formalizes a forwarding time scale that is an 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 flapping. On the other hand, the RAW forwarding decision is made at the scale of the packet rate, and uses information that must be pertinent at the present time for the current transmission(s).¶
OODA (Observe, Orient, Decide, Act) is a generic formalism to represent the operational steps in a Control Loop. The RAW Architecture applies that generic model to continuously optimize the spectrum and energy used to forward packets within a Track, instantiating the OODA steps as follows:¶
Observe:
Network Plane measurement protocols for Operations, Administration and Maintenance (OAM) to Observe some or all hops along a Track as well as the end-to-end packet delivery, more in Section 5.3;¶
Orient:
Controller plane elements to report the links statistics to a distributed or centralized control function such as a Path Computation Element (PCE), that computes and installs the Tracks, and provides meta data to Orient the routing decision, more in Section 5.4;¶
A Runtime distributed Path Selection Engine (PSE) thar Decides which DetNet Path to use for the next packet(s) that are routed along the Track, more in Section 5.5;¶
Packet (hybrid) ARQ, Replication, Elimination and Ordering Dataplane actions are controlled from the DetNet Service sublayer 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 down the Track from the PSE, more in Section 5.6.¶
+-------> Orient (PCE) --------+
|          link stats,         |
|       pre-trained model      |
|             ...              |
|                              v
Observe (OAM)                Decide (PSE)
^                              |
+-------- Act (PAREO) <--------+
At DetNet
Service sub-layer
Figure 7: The RAW OODA Loop
RAW In-situ OAM operation in the Network Plane may observe either a full Track or DetNet Paths that are being used at this time. As packets may be load balanced, replicated, eliminated, and / or fragmented for Network Coding (NC) forward error correction (FEC), the RAW In-situ operation needs to be able to signal which operation occured 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 sublayer 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 PAREO function is actioned at which RAW Node, for one a small continuous series of packets.¶
...   ..
RAN 1  -----  ...      ..  ...
/              .    ..          ....
+-------+  /              .            ..      ....    +------+
|Ingress|-                .                     .....  |Egress|
|  End  |------ RAN 2 -- .       Internet       ....---| End  |
|System |-                ..                   .....   |System|
+-------+  \               .               ......      +------+
\               ...   ...     .....
RAN n  --------  ...   .....
<------------------> <-------------------->
Observed by OAM       Opaque to OAM
Figure 8: Observed Links in Radio Access Protection
In the case of a End-to-End Protection in a Wireless Mesh, the Track is strict and congruent with the path so all links are observed.¶
Conversely, in the case of Radio Access Protection illustrated in Figure 8, the Track is Loose and only the first hop is observed; the rest of the path is abstracted and considered infinitely reliable. The loss if 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.¶
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 capture in intermediate nodes. In the example above, the Internet is opaque and not controlled by RAW; 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 whether a packet should be sent over either or a collection of those access links.¶
RAW separates the long time scale at which a Track is elaborated and installed, from the short time scale at which the forwarding decision is taken for one or a few packets (see in Section 5.1) that will experience the same path until the network conditions evolve and another path is selected within the same Track.¶
The Track computation is out of scope, but RAW expects that the Controller plane protocol that installs the Track also provides related knowledge in the form of meta data about the links, segments and possible DetNet Paths. That meta data 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 meta data may include:¶
Pre-Determined DetNet Paths to match predictable error profiles¶
Pre-Trained models¶
Link Quality Statistics and their projected evolution¶
The Track is installed with measurable objectives that are computed 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, 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.¶
The RAW OODA Loop operates at the path selection time scale to provide agility vs. the brute force approach of flooding the whole Track. The OODA Loop controls, within the redundant solutions that are proposed by the PCE, which will be used for each packet to provide a Reliable and Available service while minimizing the waste of constrained resources.¶
To that effect, RAW defines the Path Selection Engine (PSE) that is the counterpart of the PCE to perform rapid local adjustments of the forwarding tables within the diversity that the PCE has selected for the Track. The PSE enables to exploit the richer forwarding capabilities with PAREO and scheduled transmissions at a faster time scale over the smaller domain that is the Track, in either a loose or a strict fashion.¶
Compared to the PCE, the PSE operates on metrics that evolve faster, but that need to be advertised at a fast rate but only locally, within the Track. The forwarding decision may also change rapidly, 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 opposed to the PCE that must observe the whole network and optimize all the Tracks globally, which can only be done at a slow pace and using long-term statistical metrics, as presented in Table 1.¶
Table 1: PCE vs. PSE
PCE (Not in Scope)
PSE (In Scope)
Operation Typically Centralized Source-Routed or Distributed
Communication Slow, expensive Fast, local
Time Scale hours and above seconds and below
Network Size Large, many Tracks to optimize globally Small, within one Track
Considered Metrics Averaged, Statistical, Shade of grey Instant values / boolean condition
The PSE sits in the DetNet Service sub-Layer of Edge and Relay Nodes. On the one hand, it operates on the packet flow, learning the Track and path selection information from the packet, possibly making local decision and retagging the packet to indicate so. On the other hand, the PSE interacts with the lower layers and with its peers to obtain up-to-date information about its radio links and the quality of the overall Track, respectively, as illustrated in Figure 9.¶
packet | going
down the | stack
+==========v==========+=====================+=====================+
|   (iOAM + iCTRL)    | (L2 Triggers, DLEP) |       (oOAM)        |
|     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        oOAM | | packet
over | wireless        In  |                 In | | and out
v                     |                    | v
Figure 9: PSE
The main action by the PSE is the swapping of the DetNet Path within the Track for the next series of packets. The candidate DetNet Paths represent different energy and spectrum profiles, and provide protection against different failures.¶
RAW also extends the DetNet protection services (typically, PREOF) to possibly control lower layer one-hop reliability functions that are more typical to wireless than wires, including Automatic Repeat reQuest (ARQ), Forward Error Correction (FEC), Hybrid ARQ (HARQ) that includes both, 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 manipulates abstractions of the lower layer services to hint 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. The term PAREO is coined to represent both that the set of PREOF reliability functions is extended and the fact that some extensions are only controlled from Layer-3 using an abstract interface, while they are really operated at the lower layers.¶
The RAW Path Selection can be implemented in both centralized and distributed scheduling approaches. In the centralized approach, the PSE 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 PSE decision might be revised along the select 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 guaranteed SLA, e.g., by rerouting and/or adding redundancy only when a spike of loss is observed.¶
RAW uses all forms of diversity including radio technology and physical path 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 makes an attack harder to achieve.¶
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 impossible.¶
RAW will typically select the cheapest collection of links that matches the requested SLA, for instance, leverage 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.¶
This document has no IANA actions.¶
The editor wishes to thank the document co-authors:¶
Lou Berger:
Lab N¶
Xavi Vilajosana:
Wireless Networks Research Lab, Universitat Oberta de Catalunya¶
Geogios Papadopolous:
IMT Atlantique¶
Remous-Aris Koutsiamanis:
Rex Buddenberg:
Individual contributor¶
Greg Mirsky:
ZTE¶
for their contributions to the text and ideas exposed in this document.¶
This architecture could never have been completed without the support and recommendations from the DetNet Chairs Janos Farkas and Lou Berger. Many thanks to both.¶
The authors wish to thank Balazs Varga, Dave Cavalcanti, Don Fedyk, Nicolas Montavont, and Fabrice Theoleyre for their in-depth reviews during the development of this document.¶
[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>.
[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>.
[RAW-TECHNOS]
Thubert, P., Cavalcanti, D., Vilajosana, X., Schmitt, C., and J. Farkas, "Reliable and Available Wireless Technologies", Work in Progress, Internet-Draft, draft-ietf-raw-technologies-05, 2 February 2022 , <https://www.ietf.org/archive/id/draft-ietf-raw-technologies-05.txt>.
[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-08, 22 October 2022 , <https://www.ietf.org/archive/id/draft-ietf-raw-use-cases-08.txt>.
[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>.
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>.
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>.
Grossman, E., Ed., "Deterministic Networking Use Cases", RFC 8578, DOI 10.17487/RFC8578, May 2019 , <https://www.rfc-editor.org/info/rfc8578>.
[IPv6]
Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", STD 86, RFC 8200, DOI 10.17487/RFC8200, July 2017 , <https://www.rfc-editor.org/info/rfc8200>.
Finn, N. and P. Thubert, "Deterministic Networking Problem Statement", RFC 8557, DOI 10.17487/RFC8557, May 2019 , <https://www.rfc-editor.org/info/rfc8557>.
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>.
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>.
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>.
Postel, J., "Internet Protocol", STD 5, RFC 791, DOI 10.17487/RFC0791, September 1981 , <https://www.rfc-editor.org/info/rfc791>.
[TE]
Awduche, D., Chiu, A., Elwalid, A., Widjaja, I., and X. Xiao, "Overview and Principles of Internet Traffic Engineering", RFC 3272, DOI 10.17487/RFC3272, May 2002 , <https://www.rfc-editor.org/info/rfc3272>.
[STD 62]
Harrington, D., Presuhn, R., and B. Wijnen, "An Architecture for Describing Simple Network Management Protocol (SNMP) Management Frameworks", STD 62, RFC 3411, DOI 10.17487/RFC3411, December 2002 , <https://www.rfc-editor.org/info/rfc3411>.
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>.
[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>.
[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>.
[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>.
[I-D.irtf-panrg-path-properties]
Enghardt, R. and C. Krähenbühl, "A Vocabulary of Path Properties", Work in Progress, Internet-Draft, draft-irtf-panrg-path-properties-06, 22 September 2022 , <https://www.ietf.org/archive/id/draft-irtf-panrg-path-properties-06.txt>.
[IPoWIRELESS]
Thubert, P., "IPv6 Neighbor Discovery on Wireless Networks", Work in Progress, Internet-Draft, draft-thubert-6man-ipv6-over-wireless-12, 11 October 2022 , <https://www.ietf.org/archive/id/draft-thubert-6man-ipv6-over-wireless-12.txt>.
[DetNet-OAM]
Mirsky, G., Theoleyre, F., Papadopoulos, G. Z., Bernardos, C. J., Varga, B., and J. Farkas, "Framework of Operations, Administration and Maintenance (OAM) for Deterministic Networking (DetNet)", Work in Progress, Internet-Draft, draft-ietf-detnet-oam-framework-07, 6 October 2022 , <https://www.ietf.org/archive/id/draft-ietf-detnet-oam-framework-07.txt>.
[NASA]
Adams, T., "RELIABILITY: Definition & Quantitative Illustration", <https://kscddms.ksc.nasa.gov/Reliability/Documents/150814-3bWhatIsReliability.pdf>.
Pascal Thubert (editor)
Cisco Systems, Inc
45 Allee des Ormes - BP1200
06254 MOUGINS - Sophia Antipolis
Email: pthubert@cisco.com
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redpajama_set_name: RedPajamaCommonCrawl


text:
Osredek pri Trški Gori () is a small settlement in the hills above the right bank of the Sava River, beyond Trška Gora in the Municipality of Krško in eastern Slovenia. The area is part of the traditional region of Lower Carniola. It is now included with the rest of the municipality in the Lower Sava Statistical Region.

Name
The name of the settlement was changed from Osredek to Osredek pri Trški Gori in 1955.

References

External links
Osredek pri Trški Gori on Geopedia

Populated places in the Municipality of Krško

redpajama_set_name: RedPajamaWikipedia


text:
London losing Its start-up appeal as Berlin offers more for less
London has long been one of the technology capitals of the world, its Silicon Roundabout hosting some of the biggest names in the tech industry. The UK's capital city has churned out successful apps such as the Candy Crush Saga, which went to IPO this week. However, the city's unique mix of corporate finance and indie innovation, which helped it become the leader in venture capital deals and tech acquisitions in Europe, is becoming increasingly uncompetitive in comparison to the region's new growing tech hub – Berlin.
The German capital is seeing a growing inflow of high-skilled labour and start-ups, attracted by low rents and a generally cheaper standard of living despite offering similar wages to London. The city also still has a raw, creative feel, uncluttered by the commercial, mainstream success of London's high streets and the wealth of global capital. Germany's growing appeal is certainly being reflected in the numbers. According to Dow Jones VentureSource, Germany saw an inflow of £228 million in venture capital for 67 deals in Q2 2013 compared to £176 million for 77 deals in the UK over the same period. While the UK was still above Germany in total capital inflows for 2013, the Berlin-driven German landscape is quickly catching up.
Things are not helped by the UK's increasingly strict immigration policy, which is preventing new talent from arriving to the island's shores, especially from emerging economies. Brazilians, Americans and other non-EU citizens are finding it easier to obtain work permits in Germany. English is also widely spoken and is the primary language in cosmopolitan start-up offices, which was a surprise to German chancellor Angela Merkel when she toured local tech firms in 2013. Among the most notable digital players, SoundCloud, the international music service, is based in the city while tech giants Microsoft and Google are continuing expanding operations on the ground.
2014 has already seen a slew of deals for Berlin-based start-ups, suggesting a positive year ahead. Delivery Hero, a web meal delivery service, attracted £121 million, while menswear specialist Outfittery raised £11 million from the US. More deals are set to come as business transfer agents keep their eye on the burgeoning Berlin space. London's status as start-up capital of Europe is certainly under threat as new, more price-conscious companies choose Berlin.
The UK market is important for Acuity but we have developed networks beyond the UK and try and have our finger on the pulse of growing European tech hubs, of which there are increasingly many. One of the recent deals we helped to complete, for example, was for Sense One Technologies who are based in Athens, and we look forward to one day adding a Berlin firm to our portfolio of satisfied clients.


We Care Community Services strives to fill a number of needs for the people of Rhea County. They are the "working-poor"—they have jobs but struggle just to afford a place to live. Many make too much to qualify for other forms of assistance. So their situation becomes more and more difficult to remedy.