There's this Cisco 2500 with one V.35 port going to an HDSL DCE, and the ethernet port to a Cisco PIX; there are also other IPs (subnet 80.something) in the configuration on the serial side that are used to route traffic to the DSL provider.
I'm wondering if it is possible to remove the PIX and move everything on the Cisco 2500 - I can usually manage to do this when the public IP is on the wan-facing port and the private IP on the lan one, but I don't know how could I add a private IP to the 2500 and use the public one for nat when they're both on the same internal interface.
The current config for the 2500 looks like:
ip subnet-zero ! interface Ethernet0 description connected to PIX ip address 217.x.x.1 255.255.255.248 ip nat inside no ip directed-broadcast no ip mroute-cache no cdp enable ! interface Serial0 no ip address no ip directed-broadcast no ip mroute-cache encapsulation frame-relay bandwidth 1024 no cdp enable ! interface Serial0.1 point-to-point ip address 80.x.x.x 255.255.255.252 ip nat outside frame-relay interface-dlci xxx IETF bandwidth 1024 no ip directed-broadcast no cdp enable ! ip classless ip route 0.0.0.0 0.0.0.0 Serial0.1
The PIX has 217.x.x.2 on its WAN interface and uses the 2500's 217.x.x.1 as default gateway.
I would like to remove the PIX and connect the LAN directly to the Cisco 2500, which would have 192.168.1.1/24 on its Ethernet port and NAT everything out from one of the 217.x.x.X IPs. After that I will probably want to also add other static IPs to the Cisco from the 217.x.x.X/29 subnet and use them to portforward some services to internal servers.