Fundamentals of a Good Ethernet Infrastructure – Stop Chasing Ghosts in Your Network!

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How does the network performance impact the health of a process control system? This session will demonstrate how switch configuration, network design and physical infrastructure can impact the overall health of the process control system. We will run a demo that shows how controller communications can be impacted by a poor network design and implementation. The network will then be reconfigured to show how the same hardware can be reconfigured to eliminate or reduce the impact of a network anomaly on the control system.

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Fundamentals of a Good Ethernet Infrastructure – Stop Chasing Ghosts in Your Network!

  1. 1. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. PUBLIC INFORMATION Fundamentals of a Good Ethernet Infrastructure Stop Chasing Ghosts in your Network!
  2. 2. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Finding the Right Solution 2 You have 3 identical pill bottles. No distinction can be made between the pills inside. Each bottle contains 100 pills. One bottle contains pills weighing 100 mg each, in another 99 mg each, and the other 98 mg each. You may only use the scale, only once. Determine which pills are in which bottle. Hint: You are allowed to remove the pills from the bottle. Pill Bottle 1 Pill Bottle 2 Pill Bottle 3 Scale
  3. 3. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. 3 Agenda Demo 3: Querier Chaos Demo 4: A Caveat Conundrum Demo 2: Unmanaged Mishap Demo 1: Convergence Catastrophe
  4. 4. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Convergence Catastrophe  IEEE 802.1D  Layer 2 protocol that runs on bridges and switches that support 802.1D  Prevents loops when redundant paths exist in a network 4 What is Spanning Tree? This is how the switches are physical connected
  5. 5. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Convergence Catastrophe  Spanning Tree blocks a port in the loop 5 What is Spanning Tree? This is how the switches are logically connected X
  6. 6. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Convergence Catastrophe  A Root Switch is elected for each broadcast domain on the network  All switches exchange Bridge Protocol Data Units (BPDUs)  Each switches Root ID is advertised in this exchange  The lowest Root ID becomes the Root Switch  The Root Switch detects redundant paths  The optimum path is placed in a forwarding state  Non-optimum path(s) are placed in a blocked state 6 How does this occur?
  7. 7. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Convergence Catastrophe  Spanning Tree reconfigures the network  Root Switch recalculates path optimization  Paths may be rerouted  Network reconfiguration can occur when:  A redundant link in a forwarding state becomes unavailable  If network devices are added to the network  If additional paths are added on the network  Changing Port Speed/Duplex 7 What happens if the topology changes? THIS PROCESS TAKES TIME!
  8. 8. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Convergence Catastrophe 8 Example of topology changes on a production network Name IP Address Spanning- Tree Root? Vendor Model Version Up Time Topology Changes Last Topology Change / Interval Industrial Conc 100.2.198.3 RSTP No HP ProCurve J4812A - 2512 F.05.72 419 days 4,523,772 Every 0 secs ScaleHouseRock 100.2.198.4 RSTP No HP ProCurve J4813A - 2524 F.05.72 235 days 4,421,479 Every 0 secs Filtered H2O 100.2.198.5 RSTP No HP ProCurve J4813A - 2524 F.05.72 347 days 4,026,896 Every 0 secs BinControls 100.2.198.6 RSTP No HP ProCurve J4813A - 2524 F.05.72 62 days 4,397,673 Every 0 secs GatewaySwitch2 100.2.198.20 STP No HP ProCurve 8000M C.09.30 3 days 54,050 Every 15 secs Fruit Rec 100.2.198.21 STP Yes HP ProCurve 4000M C.09.30 3 days 5,062 Every 30 secs Central Process 100.2.198.22 STP No HP ProCurve 4000M C.09.30 3 days 12,940 Every 30 secs Finishing 100.2.198.23 STP No HP ProCurve 4000M C.09.30 3 days 15,890 26 hours Gateway2A 100.2.198.26 RSTP No HP ProCurve J4813A - 2524 F.05.72 19 days 1,106,872 Every 0 secs
  9. 9. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Convergence Catastrophe 9 How do topology changes accidentally occur?
  10. 10. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Convergence Catastrophe 10 What are the potential consequences on the production network? Let’s take a look and find out!
  11. 11. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Convergence Catastrophe 11 Demo 1 Network X
  12. 12. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Convergence Catastrophe  IEEE 802.1w  Layer 2 protocol that runs on bridges and switches that support 802.1D  Prevents loops when redundant paths exist in a network  The 5 different port states of Spanning Tree  Disabled  Listening  Learning  Blocking  Forwarding 12 What is Rapid Spanning Tree?
  13. 13. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Convergence Catastrophe  Does not utilize a lengthy convergence timer  The complete network topology converges in the time it takes for the BPDU packets to travel through the network  How does this occur? 13 What is Rapid Spanning Tree? This process may complete within a few 100 milliseconds
  14. 14. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Convergence Catastrophe  For use with device ports only  Skips the listening and learning stage and immediately begins forwarding  Does not create topology change when the uplink toggles  Let’s observe Demo 1 again utilizing:  Rapid Spanning Tree Protocol  Portfast on the device ports 14 What is Portfast? Key Topic: Understanding the correct protocols and configurations is vital to having a high availability network
  15. 15. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. 15 Agenda Demo 3: Querier Chaos Demo 4: A Caveat Conundrum Demo 2: Unmanaged Mishap Demo 1: Convergence Catastrophe
  16. 16. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Unmanaged Mishap  Unmanaged switches are utilized heavily on industrial networks  Unmanaged switches do not support loop protection or ring protocols  Unmanaged switches do not allow for a redundant network  Should not be used when a high availability architecture is required  Can be used on small, non-critical networks 16 Plug „n Play The Extension, A Technical Supplement to Control Network, Volume 6 Issue 1 “Managed switches are just Unmanaged switches with SNMP.” Key Topic: Understand the application requirements, and employ the correct technology
  17. 17. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Unmanaged Mishap 17 How do loops occur?
  18. 18. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Unmanaged Mishap 18 Network Drawing?
  19. 19. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Unmanaged Mishap 19 Demo 2 Network
  20. 20. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Unmanaged Mishap 20 …but I thought loops were bad?
  21. 21. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Unmanaged Mishap 21 What happens if we plug in a computer?
  22. 22. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Unmanaged Mishap  SLC™ 500s send ARP every 1,192 seconds  Ethernet/IP communication modules send ARP every 45 seconds  Different vendor communication protocols may not send ARPs at other intervals, or not at all  Implications on an unmanaged loop:  It only takes one broadcast message to shut down the network  Engineer may leave site before problem occurs  Problem may go unnoticed for months  Issue may be difficult to locate 22 Industrial Ethernet Communication Protocols
  23. 23. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. 23 Agenda Demo 3: Querier Chaos Demo 4: A Caveat Conundrum Demo 2: Unmanaged Mishap Demo 1: Convergence Catastrophe
  24. 24. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Querier Chaos  Manages the efficient delivery of multicast traffic  IGMP allows the network to understand which endpoints are interested in which multicast data  Protocol is available in virtually all managed switches, “smart” switches, and the 1783-ETAP  Layer-2 Access Switches should be configured to perform IGMP Snooping  Layer-3 Distribution Switch should be configured to perform the IGMP Querier function 24 Internet Group Management Protocol (IGMP)
  25. 25. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Querier Chaos  Ethernet/IP devices support IGMP version 2  Many other network devices support IGMP version 1  In IGMP version 1, after a host fails to respond to three queries, it is dropped from a multicast group  In IGMP version 2, hosts can also actively leave a multicast group  It is recommended for all devices to be IGMP version 2 on an Ethernet/IP  If more than one switch is configured to be IGMP Querier, the switch or router with the lowest IP address will take this role  What happens when you mix IGMP versions and different switch vendors? 25 Internet Group Management Protocol (IGMP)
  26. 26. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Querier Chaos 26 Demo 3 Network Multicast data is being produced and consumed by each controller Controller 1
  27. 27. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. 27 Agenda Demo 3: Querier Chaos Demo 4: A Caveat Conundrum Demo 2: Unmanaged Mishap Demo 1: Convergence Catastrophe
  28. 28. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Caveat Conundrums  Certain IOS versions may have known anomalies  It is important that any IOS version, currently being utilized, or being upgraded to, is properly researched for bugs  IOS anomalies may cause applications to not perform at all, perform intermittently, or only perform with certain switch configurations  An application that is working correctly can be “broken” by upgrading an IOS  A situation was recently discovered at a customer site, which exemplifies an IOS anomaly 28 The important of “Bug Scrubbing” IOS versions
  29. 29. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Caveat Conundrums  What was discovered:  If the Client and Server are in the same subnet, the communication works  If the Client and Server are in different subnets (routed), the communication does not work 29 A Client/Server Communication Problem
  30. 30. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Caveat Conundrums 30 Demo 4 Network
  31. 31. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. We care what you think!  On the mobile app: 1. Locate session using Schedule or Agenda Builder 2. Click on the thumbs up icon on the lower right corner of the session detail 3. Complete survey 4. Click the Submit Form button 31 Please take a couple minutes to complete a quick session survey to tell us how we‟re doing. 2 3 4 1 Thank you!!
  32. 32. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. www.rsteched.com Follow RSTechED on Facebook & Twitter. Connect with us on LinkedIn. PUBLIC INFORMATION Thanks

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