Workshop : Ethernet as a fieldbus Genève Friday 28th September How Ethernet becomes industrial

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1 Workshop : Ethernet as a fieldbus Genève 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 A level 2 specification : Medium Access Control in several versions So many differences between vintage Ethernet and future Ethernet! September 2001 CERN Workshop Ethernet 2 1

2 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? September 2001 CERN Workshop Ethernet 3 The everlasting confusion "I need Ethernet if I need a network able to support TCP/IP applications" September 2001 CERN Workshop Ethernet 4 2

3 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 Conclusion September 2001 CERN Workshop Ethernet 5 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 September 2001 CERN Workshop Ethernet 6 3

4 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 September 2001 CERN Workshop Ethernet 7 Level 2 QoS (1/2) Back Pressure Control Operates in half duplex mode A saturated port sends jam patterns (busy indicator) to the connected equipment, enforcing the station to Listen Before Talk 802.3x Flow Control Operates in full duplex mode A saturated port sends PAUSE packets to the connected equipment No traffic discrimination September 2001 CERN Workshop Ethernet 8 4

5 Level 2 QoS (2/2) 802.1p 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) September 2001 CERN Workshop Ethernet 9 Level 3 DiffServ Differenciated Services Uses IPv4 ToS or IPv6 priority field 64 possible levels Needs for adequate switches/routers and adapted applications September 2001 CERN Workshop Ethernet 10 5

6 TCP/IP IntServ Integrated Services 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 resources for an application flow September 2001 CERN Workshop Ethernet 11 Conclusion on QoS Management So many strategies to avoid or 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 September 2001 CERN Workshop Ethernet 12 6

7 Switched Ethernet: a case study (1/2) Ethernet Switch Station Station Station Station Station Station 6 stations, cyclically generating realtime 200 bytes packets, "tagged" high priority 100 Mbps full duplex links One store & forward switch with an average 10 µs nominal latency Coexistence with low priority traffic Compute the worst case total latency for a RT packet September 2001 CERN Workshop Ethernet 13 Switched Ethernet: a case study (2/2) 16 µs store & forward 10 µs nominal switch latency 122 µs flushing (the station can be at this moment transmitting a low priority max size frame) 80 µs queue emptying (5 RT packets already in queue) TOTAL = 228 µs September 2001 CERN Workshop Ethernet 14 7

8 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 networks September 2001 CERN Workshop Ethernet 15 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 Conclusion September 2001 CERN Workshop Ethernet 16 8

9 Vendors proposal first scheme (1/2) "I offer solutions to interconnect my fieldbus and Ethernet" A good idea Profinet (Siemens) WorldFIP September 2001 CERN Workshop Ethernet 17 Vendors proposal first 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! September 2001 CERN Workshop Ethernet 18 9

10 Vendors proposals second 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 September 2001 CERN Workshop Ethernet 19 Vendors proposals second 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! September 2001 CERN Workshop Ethernet 20 10

11 Vendors proposals second 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! September 2001 CERN Workshop Ethernet 21 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 September 2001 CERN Workshop Ethernet 22 11

12 IDA Proposal (2/2) Programming Interface IDA Object Model System Management Process Image NDDS Parametrization UDP SNMP Event Alarm Download Diagnostics (T)FTP IP Ethernet SMTP TCP HTTP September 2001 CERN Workshop Ethernet 23 Conclusion on Proposals Various solutions For various uses? Most of them not yet mature What future for IEEE 1451? September 2001 CERN Workshop Ethernet 24 12

13 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 Conclusion September 2001 CERN Workshop Ethernet 25 Security Issues Do not mistake Ethernet and Internet! Consider the plant floor network as an Intranet Networks manufacturers & designers have the knowhow 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 September 2001 CERN Workshop Ethernet 26 13

14 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 September 2001 CERN Workshop Ethernet 27 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 September 2001 CERN Workshop Ethernet 28 14

15 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? September 2001 CERN Workshop Ethernet 29 Questions? September 2001 CERN Workshop Ethernet 30 15

GUARANTEED END-TO-END LATENCY THROUGH ETHERNET

GUARANTEED END-TO-END LATENCY THROUGH ETHERNET Øyvind Holmeide, OnTime Networks AS, Oslo, Norway oeyvind@ontimenet.com Markus Schmitz, OnTime Networks LLC, Texas, USA markus@ontimenet.com Abstract: Latency