We have a DSL router and 32 public IP addresses (for example 192.168.0.0/27). The DSL router is configured by the ISP and has 192.168.0.1 at the internal side. We have a PIX 515 wit 3 Ethernet interfaces first connected to the DSL router, second connected to the internal network and third used as a DMZ.
What we want to do is to split the real addresses into to two subnets 192.168.0.0/28 and 192.168.0.16/28. Then to assign the first subnet to the interface connected to the DSL router and second to the DMZ interface. To the internal interface we want to assign a private address space, for example 10.1.1.0/24. Is it possible this configuration to work considering that no changes in the DSL router are possible and how the pix route the packets that are for the 192.168.0.16/28 ?