I have a client who is using internet access supplied by another tenant in their building. I'm trying to keep their networks hidden from one another. I have achieved this with other clients in the past by keeping them in the same scope to attach to the internet gateway router but putting them in different subnets. Right now my client cannot see any computers on the other tenants network or even ping them which is what I want. However the other tenant who is sharing their internet can find computers on our networkand they can ping us. The tenant sharing the internet is in the 192.168.0.1 scope with subnet mask 255.255.255.0. My client is in the same scope with a 255.255.0.0 subnet mask. Without any additional hardware how do I lock down this network as not to be seen.