OK, to begin with you’ll probably want to follow convention with your class C (255 address blocks) and use 192.168.x.y, where x will be your 2 subnets, 1 and 2, for example. 10.x.x.x is the (much larger) class A non-routable IP range.
Even if everything was plugged into the same switch, multicasts will be separate between the two since they go to the network id. However, you’ll want to separate the 2 networks into separate VLANs for broadcast packets - ie DHCP. A VLAN is a Virtual LAN, which occurs at the layer 2 (data link). Separate VLANs seem like you’re plugging into separate switches altogether. There are different ways of accomplishing this, the simplest being based strictly on assigned port ranges.
With a layer 3 switch you set up logical interfaces that will be used as the “default gateway”. By convention you’ll want to reserve the 192.168.x.1 address for that. For example, any 192.168.1.x node that wants to talk to 192.168.2.x would be able to if it had 192.168.1.1 set up as its default gateway. If you need to restrict who can do so, you’ll set up ACLs (access control lists) to the interface in the layer 3 switch. And/or you can just a blank default gateway in the PLCs.
Based on the “17 (managed) Ethernet switches on a fibre ring” and your requirements, you might want to consider involving a networking consultant. Home and simple networks are deceptively easy since they fit a very specific mold. Your requirements aren’t too complicated, but are getting into networking beyond guesswork.
[quote=“AlThePal”]I am installing an Ethernet/IP network with a ControlLogix processor, 16 Point I/O racks and a Red Lion G308 HMI, all connected via 17 Ethernet switches on a fibre ring.
We have now been told that we will have to pass data to a Siemens SCADA PC on a separate network. I would prefer to keep the 2 networks on separate subnets i.e. 10.0.1.x and 10.0.2.x with a subnet mask of 255.255.255.0.
Does anyone have experience in routing between subnets? I want to ensure data can only pass between the G308 HMI on one network and the SCADA PC on the other network - all multicast traffic must be stopped by the router.[/img][/quote]