1 / 35

How Ethernet becomes industrial

Workshop : Ethernet as a fieldbus Genève – Friday 28th September 2001. How Ethernet becomes industrial. Prof. Bernard Jouga - Supélec, Rennes – France Bernard.Jouga@supelec.fr. You said Ethernet…. Ethernet offers A level 1 specification : cabling systems, physical layer… in several versions

hasad
Download Presentation

How Ethernet becomes industrial

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Workshop : Ethernet as a fieldbus Genève – Friday 28th September 2001 How Ethernet becomes industrial Prof. Bernard Jouga - Supélec, Rennes – France Bernard.Jouga@supelec.fr

  2. You said Ethernet… • Ethernet offers • A level 1 specification : cabling systems, physical layer… in several versions • A level 2 specification : Medium Access Control… in several versions So many differences between vintage Ethernetand future Ethernet ! CERN Workshop Ethernet

  3. … What do you mean ? • Ethernet doesn’t offer • A complete stack up to applications, neither for the office nor for the plant ! • One standard solution for determinism and QoS issues (not yet ?) • One standard solution for connecting in industrial environment (not yet ?) • One standard solution for redundancy management • A satisfying solution for accurate stations synchronization As many Ethernet solutions as network vendors ? CERN Workshop Ethernet

  4. The everlasting confusion "I need Ethernet if I need a network ableto support TCP/IP applications" CERN Workshop Ethernet

  5. Agenda • Determinism and Qos with Ethernet • "Vintage" Ethernet • Switched Ethernet • Which QoS implementation ? • An overview of vendors proposals • Fieldbus interconnection with Ethernet/TCP/IP • Fieldbus protocols over Ethernet/TCP/IP • IDA proposal • Just one word about security • What are the real cost parameters • Conclusion CERN Workshop Ethernet

  6. Vintage Ethernet • Frame broadcasting • Along coaxial cables (10 BAS 5, 10 BAS 2) • Through multiports hubs (10 BAS T, 100 BAS T) • Collision occurrences • Function of the network size, the traffic load, the average frame size • 20% traffic load : 0,1% collisions • 40% traffic load : 5% collisions Non deterministic packet loss and packet delays CERN Workshop Ethernet

  7. Switched Ethernet • 10 Mbps, 100 Mbps, 1 Gbps • 10 Gbps in the labs ! • Frame switching on dedicated ports • On the fly / Store and forward • Half duplex /Full duplex CERN Workshop Ethernet

  8. Level 2Back Pressure • Operates in half duplex mode • A saturated port sends jam patterns (busy indicator) to the connected equipment, enforcing the station to Listen Before Talk • No traffic discrimination STOP CERN Workshop Ethernet

  9. Level 2802.3x Flow Control • Operates in full duplex mode • A saturated port sends PAUSE packets to the connected equipment • No traffic discrimination PAUSE CERN Workshop Ethernet

  10. Level 2802.1p CoS • Operates in half or full duplex modes • IEEE 802.1Q defines the general architecture for Virtual LANs and the VLAN protocol. • IEEE 802.1p defines Classes of Services Not supported by end-stations adapters Most switches will not manage the 8 Cos (2 or 4) CERN Workshop Ethernet

  11. Level 3DiffServ • Differenciated Services • End points managed • Uses IPv4 ToS or IPv6 priority field • 64 possible levels • Needs for adequate switches/routers and adapted applications CERN Workshop Ethernet

  12. TCP/IPIntServ • Integrated Services • Routers managed • Based on application identification (IPv4 sockets or IPv6 Data Flow Id) • 3 levels of services • Uses RSVP Resource reserVation Protocol to mark a path of reserved ressources for an application flow CERN Workshop Ethernet

  13. Conclusion on QoS Management So many strategies to avoidor minimize packets loss • IEEE 802.1p : a transient solution ? • DiffServ bind to IPv6 deployment ? • No future for IntServ ? • Products are just coming on the market CERN Workshop Ethernet

  14. Switched Ethernet:a case study (1/2) Ethernet Switch • 6 stations, cyclically generating realtime 200 bytes packets, "tagged" high priority • 100 Mbps full duplex links • One store & forward switch with an average 10 s nominal latency • Coexistence with low priority traffic Compute the worst case total latency for a RT packet Station Station Station Station Station Station CERN Workshop Ethernet

  15. Switched Ethernet:a case study (2/2) • 16 s store & forward • 10 s nominal switch latency • 122 s flushing (the station can be at this moment transmitting a low priority max size frame) • 80 s queue emptying (5 RT packets already in queue) • TOTAL = 228 s CERN Workshop Ethernet

  16. Transmission delays • Yet an another issue ! • In complex architectures, end-to-end delays may be lengthened by • Gateways • Proxys • … An argument for small/average size network domains CERN Workshop Ethernet

  17. Agenda • Determinism and Qos with Ethernet • "Vintage" Ethernet • Switched Ethernet • Which QoS implementation ? • An overview of vendors proposals • Fieldbus interconnection with Ethernet/TCP/IP • Fieldbus protocols over Ethernet/TCP/IP • IDA proposal • Just one word about security • What are the real cost parameters • Conclusion CERN Workshop Ethernet

  18. Vendors proposalfirst scheme (1/2) "I offer solutions to interconnect my fieldbus and Ethernet" • A good idea … • Profinet (Siemens) • WorldFIP • … CERN Workshop Ethernet

  19. Vendors proposalfirst scheme (2/2) • But not so simple… • Can I support IP applications on the fieldbus, without disturbing real time traffic ? • Can I forward fieldbus protocol messages through Ethernet segments ? • Can I have an integrated solution for the networks management ? • Delays introduced by proxies and gateway The vendor must offer a complete solution ! CERN Workshop Ethernet

  20. Vendors proposalssecond scheme (1/3) "I take my classic Fieldbus protocol and carry it on Ethernet with TCP or UDP" • A good idea … • Modbus/TCP (Schneider) • Ethernet/IP (Rockwell, IAONA) • HSE (Fieldbus Foundation) • WorldFIP EtherFIP • … CERN Workshop Ethernet

  21. Vendors proposalssecond scheme (2/3) • But not so simple… • TCP/IP protocol stack is designed for Client/server application, not for 1 producer/N Consumers exchanges • Needs switched Ethernet to insure determinism • Needs QoS management if mixed traffic with other IP applications is needed • How manage full redundancy if needed ? • How manage station synchronization if needed ? The protocol encapsulation specification is not enough ! CERN Workshop Ethernet

  22. Vendors proposalssecond scheme (3/3) • For sure not the cheapest solution ! • Needs for industrial packaged Ethernet products • Needs engineering skill if hard real time constraints • What is the value added for the end user ? All this stuff doesn't make the initial fieldbus protocol better ! CERN Workshop Ethernet

  23. IDA proposal (1/2) • Interface for Distributed Automation • NDDS, Network Data Delivery Service Middleware • Covering OSI layers 4 to 7 • Producer/Consumer Model • Broadcast and Multicast • Adapted to real time traffic CERN Workshop Ethernet

  24. IDA Proposal (2/2) Programming Interface IDA Object Model System Management Event Alarm Process Image Parametrization Download Diagnostics SMTP NDDS SNMP (T)FTP HTTP UDP TCP IP Ethernet CERN Workshop Ethernet

  25. Conclusion on Proposals • Various solutions… • For various uses ? • Most of them not yet mature • What future for IEEE 1451 ? CERN Workshop Ethernet

  26. Agenda • Determinism and Qos with Ethernet • "Vintage" Ethernet • Switched Ethernet • Which QoS implementation ? • An overview of vendors proposals • Fieldbus interconnection with Ethernet/TCP/IP • Fieldbus protocols over Ethernet/TCP/IP • IDA proposal • Just one word about security • What are the real cost parameters • Conclusion CERN Workshop Ethernet

  27. Security Issues • Do not mistake Ethernet and Internet ! • Consider the plant floor network as an Intranet • Networks manufacturers & designers have the know-how • There are solutions to secure private IP networks • (I hope that) plant floor networks (will) make use of them • Do not mistake Security and safety ! • Fieldbus manufacturers have the know-how • Mechanisms used to provide safety in classic fieldbus have to be implemented in Ethernet solutions CERN Workshop Ethernet

  28. Agenda • Determinism and Qos with Ethernet • "Vintage" Ethernet • Switched Ethernet • Which QoS implementation ? • An overview of vendors proposals • Fieldbus interconnection with Ethernet/TCP/IP • Fieldbus protocols over Ethernet/TCP/IP • IDA proposal • Just one word about security • What are the real cost parameters • Conclusion CERN Workshop Ethernet

  29. Cost parameters (1/3) • Engineering costs • Components standardization • Well-known design rules • Equipement costs • Off-the-shelf components / Customs components • Proprietary protocols / open standards • Installation costs • Number of different networks • Number of cabling systems CERN Workshop Ethernet

  30. Cost parameters (2/3) • Commissioning costs • Operators training • System testing • Proven technology & solid design • Maintenance costs • Various components resellers • Automatic discovery of new components • Avaibility of remote configuration & testing devices CERN Workshop Ethernet

  31. Cost parameters (3/3) • Operating costs • Minimization of operating HMIs • Automatic cold & warm start • Evolution Costs CERN Workshop Ethernet

  32. Agenda • Determinism and Qos with Ethernet • "Vintage" Ethernet • Switched Ethernet • Which QoS implementation ? • An overview of vendors proposals • Fieldbus interconnection with Ethernet/TCP/IP • Fieldbus protocols over Ethernet/TCP/IP • IDA proposal • Just one word about security • What are the real cost parameters • Conclusion CERN Workshop Ethernet

  33. So, Why Ethernet ? • Alternative vs. The "Fieldbus War" ? • Guarantee of durability • Multiple vendors could decrease costs • Seamless data paths • From the plant-floor to the office • For controllers, PLCs and ERP Systems • One network type • One technical expertise • A global network management CERN Workshop Ethernet

  34. One Network fits all : an utopia ? • The market today : proprietary solutions • Specific network hardware • Specific protocols • More or less compatible devices • Vendors differences based on technical performances • A challenge for setting a new market ? • COTS network hardware • One standard protocol for RT applications • A large range of Ethernet devices • Vendors differences based on value added services • A new space for systems integrators ? CERN Workshop Ethernet

  35. Questions ? CERN Workshop Ethernet

More Related