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 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 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 March 12, 2016. Copyright Notice Copyright (c) 2015 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 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 Simplified BSD License text as described in Section 4.e of Dujovne Expires March 12, 2016 [Page 1]
Internet-Draft detnet-gap-analysis September 2015 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. 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 Dujovne Expires March 12, 2016 [Page 2]
Internet-Draft detnet-gap-analysis September 2015 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 Dujovne Expires March 12, 2016 [Page 3]
Internet-Draft detnet-gap-analysis September 2015 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 Dujovne Expires March 12, 2016 [Page 4]