Best Ethernet Network Topology

The Plc Kid · Dec 21, 2009

I am planning an ethernet ip network with all ab components.

I can do a star topology from my stratix switch to all my drives and i/o or i can use 1783-etaps for my drives and use the embeded 2 port switch on my point i/o block to get a ring topology. I know ring is less wiring and bus or linear topology is not even a consideration as far as i am concerned but which is best in this application for automation equipment ring or star?

This is not a huge line but decent sized so wire savings are not much different using either method. What is best to troubleshoot?

What are other considerations?

Thanks

Da Kid

mordred · Dec 21, 2009

I've always preferred Star where possible

Alan Case · Dec 21, 2009

With the equipment you are using then the ring setup has the ability to have redundancy on a cable break. I am sure Rockwell has some powerpoints on this.
Regards Alan Case

Art@PLCH · Dec 21, 2009

I would go with a star just because of reliability considerations, if a cable breaks or any other hardware failure is experienced then it will affect only that piece of the star (failure of a switch will take down the whole network nonetheless). Whereas in a ring a single cable failure will affect the entire ring unless you implement means to route around the failed node. Also, from the troubleshooting stand point the star is easier in my opinion with that single link from switch to client.

The Plc Kid · Dec 21, 2009

These components use a self healing ring with diagnostics to give direction to the fault. You only loose the node that had the problem. Nothing upstream or downstream of it.

Hydro Power Guy · Dec 22, 2009

Depends on the requirements of your application. If you can tolerate lower availability then use a star. Otherwise use a ring.

If you have a large number of nodes and I/O the I would probably break it into several rings due to bandwidth considerations. IMHO a star is better to segment/switch your bandwidth. It only puts the traffic where it needs to go. If you use a ring, all traffic goes through one pipe.

Pandiani · Dec 22, 2009

Why not use the ring all the time? I think that in industrial application ring topology is mostly preferred over any other topology. Most network topologies in an industrial floor I have seen use ring topology with managed switches.
You need to use switches to prevent packets looping.
I'm also intersting to learn what is the most common network topology in industry today.

Regards,

Pandiani

lostcontrol · Dec 22, 2009

Why not use the ring all the time? I think that in industrial application ring topology is mostly preferred over any other topology

Ring for inter-network connections, star from network access to device, if this makes sense.

If all the devices are connected in a ring, then if both ends happen to fail, then you will lose all the devices in between. By connecting devices in star topology sorta prevents this... My 2c

robw53 · Jan 1, 2010

lostcontrol said:
Ring for inter-network connections, star from network access to device, if this makes sense.

what exactly do you mean by this?

lostcontrol · Jan 1, 2010

For different locations around the plant, when devices such as PLC's & HMI's are to be connected, a typical configuration is to have a fibre ring, so if one leg fails, communications will continue.

Whilst this illustration isn't exactly what I mean, it shows PC's as opposed to switches, it gives an idea.
http://compnetworking.about.com/od/...-Topologies/Ring-Network-Topology-Diagram.htm

Then this is a star network.
http://compnetworking.about.com/od/...-Topologies/Star-Network-Topology-Diagram.htm
If you take this diagram, and have say 5 of these pic's, the switch at the top would all be connected in a ring.

Does that make a bit more sense?

robw53 · Jan 1, 2010

sorry my fault i didnt make it clear, i know about ethernet topology and redundancy etc etc i ment when you talk about

"inter-network connections" and "network access to device"

rob

lostcontrol · Jan 1, 2010

"inter-network connections"

I would call this 'switch to switch', or 'area to area'

"network access to device"

This would be say from PLC to drive/HMI/Remote IO/any other Ethernet type device that is specific to that controller.

robw53 · Jan 1, 2010

cheers for that, one them things that mite come up in future conversations!

Best Ethernet Network Topology

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