AB ethernet network crashing

[mmcdermott1]

I disagree, the overall point is not being missed at all. The OP has a problem, and we are trying to help resolve it.

You say yourself the IP and subnet mask should not matter, and I think most would agree so of course we are going to point out the "obvious". Especially when we have no further information of the system architecture. Many questions from members have been asked, yet feedback information is lacking. The OP says this behavior was seen during debug on the shop floor. How did it leave the shop floor if it had a known problem?

We don't have a crystal ball into your network and system and what you've already done for trouble shooting.

The origin im pretty sure works or worked for my company so I am very familiar with the issue (I just worked on it last week). This isn't a control issue, its a network issue. Take PLC's and such out of the equation. On just a standard office network, a subnet mask should NOT be causing crashes, this defies networking 101. And in terms of why this was released knowing it has issues, that is an unfortunate reality people like me have to deal with within this company. Not fun.

 

[cbuysse]

Anyone else happen to notice the date on the original post? This is a 2.5 year old thread. I would suspect the problem has either been solved or abandoned.

 

[mmcdermott1]

Yes it's old
As mentioned, I THINK the person that originally posted this worked for my company and was dealing with this issue then. It's still an issue. If this isn't a person from my company that worked on this same line I would be amazed because it sounds like it is.

 

[flux]

Just curious. When you plug in the laptop with the .254 subnet mask. Did you have a program running or maybe trying to connect to a plc?

Does it crash when there is no program running?

 

[mmcdermott1]

No but doesnt matter if you do. We have also tried probably 10 different laptops and also Windows XP as well as 7. Doesnt seem to be any specific laptop or OS. Seems to be ANY laptop

 

[dmargineau]

I believe it has something to do with the managed EtherNet/IP switching.
Configuring a 254 third octet allows the PC to connect to another "invisible" network matching the first two octets, "network" used by the software running on the managed switch(es)in order to ensure the configured functionality.

What CPU firmware revision are you running? Have you considered updating to Rev 17 or higher, unicast the I/O and use unmanaged switching?
Also, segregating the HMI applications on a separate subnet might alleviate this kind of issues.

Just my two cents...:nodi:

 

[mmcdermott1]

They actually run versions higher than 17 (on the logix platforms).
We also have lines in the company that have far more devices, some having over 200 ethernet/ip devices.
This isnt a traffic issue. Why would you want to go to unmanaged switches?
And again, CPU firmwares and what is segregated or what is on what VLAN still does not explain the subnet mask issue. It does not matter what subnet mask a computer has, it should NEVER cause a network to crash.

 

[dmargineau]

It is not a "traffic amount" issue, but a "traffic configuration" one...
Why would you need managed switching on a Level 0 subnet with Unicast provisions?! Probably because present, un-segregated broadcast HMI applications...
I have laid out and comissioned systems with 3-400 EtherNet/IP modules which used exclusively unmanaged switching on Level 0 subnets.
The only required usage of managed switching I have encountered is between the "logical levels" and the VLAN in order to "prioritize" SCADA applications' functionality.

 

[mmcdermott1]

These machines are also on a larger layer 3 network. We use all managed switching for routing and vlans.

 

[darkesha]

My best guess to do is to substitute managed switches with dumb ones. If network doesn't kick out you would know what's the problem and you could write email to the manufacturer of the managed switches asking about what had been configured wrong in their switch. That would probably solved the problem.

Right now you have to find out what causing it and the best thing to do that is to have things replaced.

 

[flux]

I think your switch gets confused when it sees a foreign network (not 255.255.255.0) and thinks its being DDOS attack and then shuts the ports down.

How do you restore the network when it crashes?