Ethernet Subnet Mask

[Phrog30]

Do they plan to put connect thius to the corporate network in any way? If they do they are in for a nice surprise.

Yes, for data collection... not sure what they use though, or plan to use.

 

[jkerekes]

NFW!!!. Idiots. They are just begging for problems.

They need to get someone from rockwell in to talk to them. Sounds like your IT dept is a bunch of idiots cause any IT work his salt know better than that on any system.

By using a 255.0.0.0 subnet mask that is called supernetting and it will be pure disaster on the floor if they do this.

The system will be very unpredictable and can lose comms at any time.

I'm also learning the best pratices for deploying Ethernet and Ethernet/IP. What's wrong with supernetting? Doesn't it just give you more usable IP addresses on the the same subnet. Or am I missing something?

 

[daba]

I'm also learning the best pratices for deploying Ethernet and Ethernet/IP. What's wrong with supernetting? Doesn't it just give you more usable IP addresses on the the same subnet. Or am I missing something?

You are missing the concept of bandwidth a network segment should only carry the data that it needs to. By implementing a "do-all" subnet, the cables are carrying traffic not intended for that context, and any decent IT person worth his salt would know this.

Subnetting was designed to allow traffic to pass only to/through "interested" devices.

 

[The Plc Kid]

I'm also learning the best pratices for deploying Ethernet and Ethernet/IP. What's wrong with supernetting? Doesn't it just give you more usable IP addresses on the the same subnet. Or am I missing something?

As Daba said bandwidth is a major issue with supernetting. Also if the company in question ties thses devices to their corporate lan and don't do it correctly they will have more issues site wide as there will be devices with unicast,broadcast and maybe multicast traffic depending on the logix firmware rev.

Unmanaged switches make multicast traffic look and feel like broadcast traffic and in this case would hit every node on every subnet with the mask they are planning to use and this would happen for each multicast message at fast RPI rates this won't take long to become a problem.

It will be one of those things where weird things happen all over the place and you cycle power and they may or may not go away for a while. Maybe go away for a hour,a day,a week. It is very unreliable and unpredictable which are two things you don't want in a automation system.