Re: NAT and same IP address

PetriH112233 · ‎06-12-2019

Hello everybody!

I have C2900 with version 15.3.

One interface is configured as 10.253.110.234 and is having 10.253.110.0/24 and my computer is connected here as 10.253.110.223.

Second interface is configured as 192.168.23.100 and is having 192.168.23.0/24.

Third interface is configured as 192.168.24.100 and is having 192.168.24.0/24.

192.168.23.0/24 and 192.168.24.0/24 have various hosts and it's hard or nearly impossible to configure router to them all.

My idea was that I will NAT my 10.253.110.223 to 192.168.23.99 and then 192.168.24.99, but I realized that it's not possible. It cannot NAT same static address to multiple addresses.

Is there anyway to achieve this configuration that 10.253.110.223 is seen in 192.168.23.0/24 as 192.168.23.99 and 192.168.24.0/24 as 192.168.24.99?

Have a nice day!

Giuseppe Larosa · ‎06-12-2019

Hello Petri,

I don't see any need for NAT in your network :

all IP subnets are not overlapping and private IP addresses.

You just need routing enabled to make posssible communication between hosts in the three subnets.

If all hosts are using your router as default gateway you should be fine.

Hope to help

Giuseppe

Hector Gustavo Serrano Gutierrez · ‎06-12-2019

Hi @PetriH112233,

You can try something like:

route-map NET_23
 match interface GigabitEthernet0/x
!
route-map NET_24
 match interface GigabitEthernet0/y
!
ip nat inside source static 10.253.110.223 192.168.23.99 route-map NET_23 extendable
ip nat inside source static 10.253.110.223 192.168.24.99 route-map NET_24 extendable

I am taking for granted that Gig0/x and Gig0/y (corresponding to 192.168.23.100 and 192.168.24.100 respectively) are configured with ip nat outside while the interface with 10.253.110.234 is configured with ip nat inside.

I haven't tested it myself yet.

PetriH112233 · ‎06-19-2019

@Hector Gustavo Serrano Gutierrez wrote:
Hi @PetriH112233,
You can try something like:
route-map NET_23
 match interface GigabitEthernet0/x
!
route-map NET_24
 match interface GigabitEthernet0/y
!
ip nat inside source static 10.253.110.223 192.168.23.99 route-map NET_23 extendable
ip nat inside source static 10.253.110.223 192.168.24.99 route-map NET_24 extendable
I am taking for granted that Gig0/x and Gig0/y (corresponding to 192.168.23.100 and 192.168.24.100 respectively) are configured with ip nat outside while the interface with 10.253.110.234 is configured with ip nat inside.

I haven't tested it myself yet.

Thank you very much of your reply. This works as intended.

Any idea how to do it also with ASA? My ASA version is 9.8 and ADSM version 7.8.

Petri