Terminology in IPv6 over Time Slotted Channel Hopping
draft-palattella-6tsch-terminology-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
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|---|---|---|---|
| Authors | Maria Rita Palattella , Pascal Thubert , Thomas Watteyne , Qin Wang | ||
| Last updated | 2013-03-11 | ||
| Replaced by | draft-ietf-6tisch-terminology, draft-ietf-6tisch-terminology | ||
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draft-palattella-6tsch-terminology-00
6TSHC MR. Palattella, Ed.
Internet-Draft SnT/Univ. of Luxembourg
Intended status: Informational P. Thubert
Expires: September 11, 2013 cisco
T. Watteyne
Linear Technology / Dust Networks
Q. Wang
Univ. of Sci. and Tech. Beijing
March 10, 2013
Terminology in IPv6 over Time Slotted Channel Hopping
draft-palattella-6tsch-terminology-00
Abstract
6TSCH proposes an architecture for an IPv6 multilink subnet that is
composed of a high speed powered backbone and a number of
IEEE802.15.4e TSCH wireless networks attached and synchronized by
backbone routers. This document extends existing terminology
documents available for Low-power and Lossy Networks to provide
additional terminology elements.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC
2119 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Drafts is at http://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 September 11, 2013.
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Copyright Notice
Copyright (c) 2013 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
(http://trustee.ietf.org/license-info) in effect on the date of
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 6
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Normative References . . . . . . . . . . . . . . . . . . 6
6.2. Informative References . . . . . . . . . . . . . . . . . 6
6.3. External Informative References . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
A new breed of Time Sensitive Networks is being developped to enable
traffic that is highly sensitive to jitter and quite sensitive to
latency. Such traffic is not limited to voice and video, but also
includes command and control operations such as found in industrial
automation or in-vehicule sensors and actuators.
At IEEE802.1, the "Audio/Video Task Group", was rename TSN for Time
Sensitive Networking. The IEEE802.15.4 Medium Access Control (MAC)
has evolved with IEEE802.15.4e which provides in particular the Time
Slotted Channel Hopping (TSCH) mode for industrial-type applications.
Both provide Deterministic capabities to the point that a packet that
pertains to a certain flow crosses the network from node to node
following a very precise schedule, like a train leaves intermediate
stations at precise times along its path.
This document provides additional terminology elements to cover terms
that are new to the context of TSCH wireless networks and other
deterministic networks.
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2. Terminology
The draft extends [I-D.ietf-roll-terminology] which is included here
by reference.
The draft does not reuse terms from IEEE802.15.4e such as "path" or
"link" which bear a meaning that is quite different from classical
IETF parlance.
This document adds the following terms:
6TSCH: Entity that sets up the schedule, controls the
connectivity graph of the network, and the resources
allocated to each scheduled cell in that connectivity
graph. It may be an adaptation layer, a distributed
reservation protocol, a centralized path computation
entity, or any combination thereof.
6tus: 6tus (pronounced "sixtus") is the adaptation layer
between TSCH and upper layers like 6LoWPAN and RPL. It
is defined in [I-D.draft-wang-6tsch-6tus].
6tus Data Convey Model: Model describing how the 6tus adaptation
layer feeds the data flow coming from upper layers into
TSCH. It is composed by an I-MUX module, a MUX module, a
set of priority queues, and a PDU (Payload Data Unit).
ASN: Absolute Slot Number, the timeslot counter, incremented
by one at each timeslot. It is wide enough to not roll
over in practice. See
[I-D.watteyne-6tsch-tsch-lln-context].
Blacklisting: Set of frequencies which should not be used for
communication.
Bundle: A group of equivalent scheduled cells, i.e. cells
identified by different (slotOffset, channelOffset),
which are scheduled for a same purpose, with the same
neighbor, with the same flags, and the same slotframe.
The size of the bundle refers to the number of cells it
contains. Given the length of the slotframe, the size of
the bundle translates directly into bandwidth, either
logical, or physical.
Cell: A single element in the TSCH schedule, identified by a
slotOffset and a channelOffset value. A cell can be
scheduled or unscheduled. During an unscheduled cell,
the node does not communicate. When a cell is scheduled,
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it is assigned a MAC-layer slotframe identifier, a
neighbor MAC address (which can be the broadcast
address), and one or more of the following flags: TX, RX,
shared, timeskeeping, hard. A broadcast cell is an alias
for "a scheduled cell with neighbor address the broadcast
address".
ChannelOffset: Identifies a row in the TSCH schedule. The number of
available channelOffsets is equal to the number of
available frequencies. The channelOffset translates into
a frequency when the communication takes place, resulting
in channel hopping, as detailed in
[I-D.watteyne-6tsch-tsch-lln-context].
Dedicated Cell: A cell that is reserved for a given node to transmit
to a specific neigbor.
Distributed cell reservation: A reservation of a cell done by one or
more in-network entities (typically a connection
endpoint).
Distributed track reservation: A reservation of a track done by one
or more in-network entities (typically a connection
endpoint).
EB: Enhanced Beacon frame used by an avertising node to
announce the presence of the network. It contains
information about timeslot length, current ASN value,
slotframes and timeslots the beaconing mote is listening
on, and a 1-byte join priority (i.e., number of hops
separating the node sending the EB, and the PAN
coordinator).
GMPLS: Generalized Multi-Protocol Label Switching, a 2.5 layer
service that is used to forward packets based on the
concept of generalized labels.
Hard Cell: A scheduled cell that is locked, i.e., it cannot be moved
by 6tus in the schedule. See
[I-D.draft-wang-6tsch-6tus].
IE: Information Elements, a list of Type-Length-Value
containers placed at the end of the MAC header, used to
pass data between layers or devices. A small number of
types are defined by TSCH, but a range of types is
available for extensions, and thus, is exploitable by
6TSCH. See [I-D.watteyne-6tsch-tsch-lln-context].
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I-MUX module: Inverse-Multiplexer, a classifier that receives
6LoWPAN frames and places them into priority queues.
Logical Cell: A cell that correspond to granted bandwidth but is
only lazily associated to a physical cell, based on
usage.
MUX module: Multiplexer, the entity that dequeues frames from
priority queues and associates them to a cell for
transmission.
PCE: Path Computation Entity, the entity in the network which
is responsible for building and maintaining the TSCH
schedule, when centralized scheduling is used.
PCE cell reservation: The reservation of a cell done by the PCE.
PCE track reservation: The reservation of a track done by the PCE.
Provisioned Cell: A soft cell which provides redundancy above the
required bandwidth to ensure some QoS level.
QoS: Quality of Service.
Shared Cell: A cell that is used by transmitted nodes at the same
time and on the same channelOffset. Only cells with TX
flag can be marked as "shared". A backoff algorithm is
used to resolve contention.
SlotOffset: Identifies a column in the TSCH schedule, i.e. the
number of timeslots since the beginning of the current
iteration of the slotframe.
Slotframe: A MAC-level abstraction that is internal to the node and
contains a series of timeslots of equal length and
priority. Multiple slotframes can coexist in a node's
schedule, i.e., a node can have multiple activities
scheduled in different slotframes, based on the priority
of its packets/traffic flows. The timeslots in the
Slotframe are indexed by the SlotOffset; the first
timeslot is at SlotOffset 0.
Soft Cell: A scheduled cell that is not locked, i.e., it may be
moved in the schedule within a same slotframe by 6tus
[I-D.draft-wang-6tsch-6tus].
Timeslot: A basic communication unit in TSCH which allows a
transmitter node to send a frame to a receiver neighbor,
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and that receiver neighbor to optionally send back an
acknowledgment. The length of the timeslot determines
the maximum size of the frame and the number of
acknowledgements (in case multiple are used, e.g.,
duocast), that can be exchanged.
Time Source Neighbor: A neighbor a node uses as its time reference,
and to which it needs to keep its clock synchronized. A
node can have one or more time source neighbors.
Track: A determined sequence of cells along a multi-hop path.
This is typically the result of a reservation.
TSCH: Time Slotted Channel Hopping, a medium access mode of the
[IEEE802154e] standard which uses time synchronization to
achieve ultra low-power operation and channel hopping to
enable high reliability.
TSCH Schedule: A matrix of cells, each cells indexed by a slotOffset
and a channelOffset. The slotframe size (the "width" of
the matrix) is the number of timeslots it contains. The
number of channelOffset values (the "height" of the
matrix) is equal to the number of available frequencies.
The TSCH schedule contains all the scheduled cells from
all slotframes and is sufficient to qualify the
communication in the TSCH network.
3. IANA Considerations
This specification does not require IANA action.
4. Security Considerations
This specification is not found to introduce new security threat.
5. Acknowledgements
6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
6.2. Informative References
[I-D.draft-thubert-6tsch-architecture]
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Thubert, P., Ed., Assimiti, R., and T. Watteyne, "An
Architecture for IPv6 over Time Synchronized Channel
Hopping. draft-thubert-6tsch-architecture-00 (work in
progress) ", March 2013.
[I-D.draft-wang-6tsch-6tus]
Wang, Q., Ed., Vilajosana, X., and T. Watteyne, "6tus
Adaptation Layer Specification. draft-wang-6tsch-6tus-00
(work in progress) ", March 2013.
[I-D.ietf-roll-terminology]
Vasseur, J., "Terminology in Low power And Lossy
Networks", draft-ietf-roll-terminology-11 (work in
progress), February 2013.
[I-D.watteyne-6tsch-tsch-lln-context]
Watteyne, T., "Using IEEE802.15.4e TSCH in an LLN context:
Overview, Problem Statement and Goals", draft-watteyne-
6tsch-tsch-lln-context-01 (work in progress), February
2013.
6.3. External Informative References
[IEEE802154e]
IEEE standard for Information Technology, "IEEE std.
802.15.4e, Part. 15.4: Low-Rate Wireless Personal Area
Networks (LR-WPANs) Amendament 1: MAC sublayer", April
2012.
Authors' Addresses
Maria Rita Palattella (editor)
University of Luxembourg
Interdisciplinary Centre for Security, Reliability and Trust
4, rue Alphonse Weicker
Luxembourg L-2721
LUXEMBOURG
Phone: (+352) 46 66 44 5841
Email: maria-rita.palattella@uni.lu
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Pascal Thubert
Cisco Systems, Inc
Village d'Entreprises Green Side
400, Avenue de Roumanille
Batiment T3
Biot - Sophia Antipolis 06410
FRANCE
Phone: +33 497 23 26 34
Email: pthubert@cisco.com
Thomas Watteyne
Linear Technology / Dust Networks
30695 Huntwood Avenue
Hayward, CA 94544
USA
Phone: +1 (510) 400-2978
Email: twatteyne@linear.com
Qin Wang
Univ. of Sci. and Tech. Beijing
30 Xueyuan Road
Beijing, Hebei 100083
China
Phone: +86 (10) 6233 4781
Email: wangqin@ies.ustb.edu.cn
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