Internet DRAFT - draft-dujovne-detnet-gap-analysis
draft-dujovne-detnet-gap-analysis
6TiSCH D. Dujovne, Ed.
Internet-Draft Universidad Diego Portales
Intended status: Informational September 9, 2015
Expires: March 12, 2016
Deterministic Networks Gap Analysis
draft-dujovne-detnet-gap-analysis-01
Abstract
This document introduces and describes several conditions and use
cases where the use of an IP-based layer-3 and up is required to
provide a complete networking solution to deterministic networks.
The contents of this work is a gap analysis to contribute to the
design and development of a number of complimentary modules to
provide IP-enabled networking for deterministic networks.
Status of This Memo
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This Internet-Draft will expire on March 12, 2016.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Gap Analysis . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. 6TiSCH Track management . . . . . . . . . . . . . . . . . 3
3.2. Deterministic Payload on MPLS . . . . . . . . . . . . . . 3
3.3. Traffic Specification implementation for PCE . . . . . . 3
3.4. Packet-track ID . . . . . . . . . . . . . . . . . . . . . 3
3.5. Packet Redundancy Protocol . . . . . . . . . . . . . . . 4
4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 4
5. Informative References . . . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
The first step to become detnet networks was taken at the stub
networks such as 6TiSCH-based ones [I-D.ietf-6tisch-tsch], meaning
those simple networks that connect the endpoints to one or several
gateways, thus enabling both a predictable delay and a very high
reliability. These two characteristics must be preserved along the
the multi-hop path between source and destination, thus requiring a
fully-fledged deterministic end-to-end network including management
services to achieve this goal. This is achieved by installing tracks
with all the deterministic capabilities.
The evolution towards these kinds of intermediate and backbone
deterministic networks has been taken up to the MAC layer by the IEEE
by defining several standards to provide building blocks to guarantee
a predictable delay, such as buffers, queues and schedulers. The
configuration, use, coordination, resources management and control of
these blocks must be achieved at a higher layer, tightly linked to
the routing scheme. Many applications are currently lacking this
kind of solution, forcing bandwidth overprovisioning to reduce packet
loss and delay uncertainty.
2. Assumptions
Current packet loss and delay jitter provided by IP networks are not
enough for industrial applications
Realtime audio and video for reliable content distribution in local
networks is cannot be achieved without time-scheduled IP networks
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End-to-end delay and packet loss guarantees cannot be provided
without a managed deterministic network
3. Gap Analysis
3.1. 6TiSCH Track management
6TiSCH requires the installation of tracks along a path with
deterministic capabilities, including scheduled transmissions,
intermediate queue management, synchronization and path and packet
redundnacy among others. The mechanism to achieve such a path is
achieved by using PCE/SDN operations as defined on RFC 7149
[RFC7149].
On 6TiSCH, IPv6 packets are carried on installed tracks; to reduce
resource usage, there is also the need to forward IPv6 packets by
opportunistic reuse of track slots and also reuse link bundle slots
to forward schedule packets that missed their track. Both mechanisms
require the use of Deterministic Networking managament capabilities.
3.2. Deterministic Payload on MPLS
There are certain Non-IP protocols such as Profibus and Modbus which
can be carried as IPv6 payload as long as this traffic is treated as
Deterministic; this can be achieved by the use of MPLS and and a
specific mangement module for layer-2 path redundancy, such as
Parallel Redundancy Protocol.
3.3. Traffic Specification implementation for PCE
There are several issues on the implementation of Traffic
Specification for the PCE
[I-D.ietf-teas-interconnected-te-info-exchange]:
A TEAS adaptation to carry the topology (neighbors, link quality,
interference test, etc.) and capabilities (buffers, queues and
timers) from the point of view of the individual devices.
A CCAMP/RSVP-TE adaptation to program the individual tracks
An adaptation of PCEP to push an individual device schedule
3.4. Packet-track ID
Track ID on packets is not defined yet; the use of Diffserv/DSCP and
MPLS (and G-MPLS for 6TiSCH) are possible alternatives
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3.5. Packet Redundancy Protocol
There is a need to define a Packet Redundancy Protocol (PRP) for
deterministic networks, including the PRP sequence number which can
be defined by the ASN.
4. Acknowledgments
Thanks to the Fondecyt (CONICYT-Chile) 11121475 Project.
5. Informative References
[I-D.ietf-6tisch-tsch]
Watteyne, T., Palattella, M., and L. Grieco, "Using
IEEE802.15.4e TSCH in an IoT context: Overview, Problem
Statement and Goals", draft-ietf-6tisch-tsch-06 (work in
progress), March 2015.
[I-D.ietf-teas-interconnected-te-info-exchange]
Farrel, A., Drake, J., Bitar, N., Swallow, G., Ceccarelli,
D., and X. Zhang, "Problem Statement and Architecture for
Information Exchange Between Interconnected Traffic
Engineered Networks", draft-ietf-teas-interconnected-te-
info-exchange-02 (work in progress), March 2015.
[RFC7149] Boucadair, M. and C. Jacquenet, "Software-Defined
Networking: A Perspective from within a Service Provider
Environment", RFC 7149, DOI 10.17487/RFC7149, March 2014,
<http://www.rfc-editor.org/info/rfc7149>.
Author's Address
Diego Dujovne (editor)
Universidad Diego Portales
Escuela de Informatica y Telecomunicaciones
Av. Ejercito 441
Santiago, Region Metropolitana
Chile
Phone: +56 (2) 676-8121
Email: diego.dujovne@mail.udp.cl
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