Hello,

I had to use a Scalance S612 to protect a network from intrusion.

In simple word, there is an unsafe external network (like internet) and you need to protect your safe internal network (PLCs, HMI etc...).

There is litteraly a external and internal network plug on the S612.

I had to access multiple IP address range in the internal network, 192.168.0.X and 192.168.1.X.

I had hard time doing it and I thought it would be great for people to know how to do it.

Everything is in understanding of the subnet mask!

I always used 255.255.255.0, because... I always did it...

Let's say I have a PLC with 192.168.0.1 and 255.255.255.0.

What the subnet mask do is let the PLC communicate with all the devices with address 192.168.0.X.

Let's say I put subnet mask 255.255.254.0 to everybody, all the devices with address 192.168.0.X and 192.168.1.X will be in the subnet and able to communicate with each others.

You see where I go, if I put 255.255.0.0, all the devices 192.168.X.X will be in the same subnet and able to communicate with each other.

So, for my application I needed to access to devices with 192.168.0.X and 192.168.1.X, I just had to set all the subnet mask of the devices in the network to 255.255.254.0.

I am now able to access to all devices in the internal network.

I join a PDF of my application to the topic for better understanding.

Hope to have learn something to someone.

Have a good day!

Best regards,

Hugo

Petri H

Does this increase network traffic between S612s?

 The X300 Switches should learn were the ip partners are and only use this ports, so no there should not be more traffic.

Subnetmask devides the network and the host part. Maybe it is more clear to understand if one changes to binary writing. 254 instead off 255 means the last bit is kept to the host part which therefore uses 9 instead of 8 bits as a adress range. You can also test setting the mask for the plcs to 255 so that they only see their traffic. Did not know that network masks are still unknown things.

https://en.wikipedia.org/wiki/Subnetwork