I can share my original setup just give you an idea.
I have my LMCE box behind another firewall also, I do not use my LMCE box as a gateway.
The external NIC of the LMCE box is connected to my normal LAN with an IP range of 10.0.0.X
the internal NIC of my LMCE box is connected to another switch that is isolated from my LAN so that I can boot my MDs.
And I did not have to disable my DHCP that way.
That is probably the simplest setup to achieve what you want.
I no longer use that setup, I use an l3 switch and utilize vlans now, as hari was getting at. A little more complicated that way, but saves having to setup a second isolated LAN for MDs.
I have my LMCE box behind another firewall also, I do not use my LMCE box as a gateway.
The external NIC of the LMCE box is connected to my normal LAN with an IP range of 10.0.0.X
the internal NIC of my LMCE box is connected to another switch that is isolated from my LAN so that I can boot my MDs.
And I did not have to disable my DHCP that way.
That is probably the simplest setup to achieve what you want.
I no longer use that setup, I use an l3 switch and utilize vlans now, as hari was getting at. A little more complicated that way, but saves having to setup a second isolated LAN for MDs.