Redundant Ethernet Implementation

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Thread Starter

Paul Jager

We are investigating implementation of a fully redundant Ethernet with TCP/IP for Linux and NT using automationX.

3COM makes a dual port card - the 3C928-TXM. Anyone tried these successfully?

Would like to know others experiences in implementing the same, OS tweaks, methods, products and hardware used etc.

Thank You,

Paul Jager
CEO
www.mnrcan.com
 
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Alex Pavloff

> Would like to know others experiences in implementing the
> same, OS tweaks, methods, products and hardware used etc.

In addition to getting a dual port card, you're going to have to setup two completely seperate ethernet networks. Having two cables from the same hub going into the same card will buy you nothing.

In addition, a dual port card like the 3C982 is no different than putting two one port ethernet cards in your PC. The 3C982 just looks like 2 NICs (probably 3C980), and you're still going to have to deal with the network setup, which can get a little tricky.

The setup of the PCs and any switches/routers are going to be the hardest part of a fully redundant ethernet. I would recommend talking to someone
who sets up large networks and servers for a living.

Alex Pavloff
Software Engineer
Eason Technology

 
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Lynn August Linse

Few people today go the dual-port-on-one-card routine. Why pay $600 for 1 dual-port card which is only maybe 40% "redundant" when you can buy 2 x $39 cards for full redundancy.

In theory the dual-port cards offer bumpless fail-over without loss of even the TCP socket connection, but how will you prove this in a control situation? Plus it makes you dependent on a single-source card which could be discontinued any day.

I'd suggest it's a better long-term investment to spend the time getting dual card, dual-IP designs to work well enough.

Best Regards

Lynn August Linse, [email protected] http://www.linse.org/lynn
3 Rue Monet, Foothill Ranch CA 92610
Ph: 949-300-6337 Fx: 612-677-3253
 
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Ralph Mackiewicz

> We are investigating implementation of a fully redundant Ethernet with
> TCP/IP for Linux and NT using automationX.
>
> Would like to know others experiences in implementing the same, OS
> tweaks, methods, products and hardware used etc.

Before you get involved in elaborate redundancy systems make sure you define more precisely what is meant by "fully redundant Ethernet". Do you
mean the physical network media? All the switches, routers, etc.? Do the computers running the applications need to be redundant? Do the
applications need to be redundant?

If all you need is redundant media there are dual port transceivers that can be purchased to provide low-cost redundancy for both UTP and fiber
media without having to go to the considerable expense of making everything redundant.

> Visit our auction for a complete control system on Ebay at:
> http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=1646623190

I went there and the description of this item was:

> Hot PLC! Allen Bradley Modicon Opto Wago TDC

While the item listed was not an Allen-Bradly, Modicon, Opto, Wago, or Honeywell PLC/TDC but a small AutomationX DCS that can optionally interface to the I/O systems of these manufacturers. The item description is a bit
misleading.

Regards,
 
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From the diagram we have client server arrangement wired, dual hubs/switches, connecting to a Fiber Ethernet with 1pr. Multi-mode.

The automationX servers are redundant, or you can call one the main and the other the hot standby. We've done that many times. What we haven't done is dual cables and NIC's for the Ethernet to the clients or the field I/O as Ethernet for field use is fairly new.

I don't necessarily agree with the need for a backup wired network, but for now it's by specification.

The dual port card will fit if the failover is automatic and ideally transparent to automationX. So I think that is the route we'll test. 3Com sales support claims it's doable in the dual port NIC but the details they could not provide. The 3Com cards are about $200 each.

As for our Ebay description - you would never bid on it based on the description. The description is there to be hit on searches for those
products, as it can be used with any of them, simultaneously.

Thanks for your input.

Paul
 
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