NAT a subnet to a single Public address

[ronnie.loraine]

Hello!

I have a SDSL 878 router with a single IP address on the Dialer interface.  I also have a /29 subnet of public addresses routed to this interface.  This router is also providing the NAT between the private and public.

Requirement is VLAN 1 is to NAT to the dialer IP (e.g. 1.1.1.1).   VLAN 2 is to NAT to one of the /29 address (e.g. 2.2.2.2)

Config I have so far is:

!

ip nat inside source route-map NATTING interface Dialer0 overload

route-map NATTING permit 1
match ip address 100

access-list 100 permit ip 192.168.5.0 0.0.0.255 any  (vlan 1)
access-list 100 permit ip 172.16.10.0 0.0.0.255 any  (vlan 2)

!

When I enter my NAT statements with a route-map or list I only have the options for interface or pool.  With the pool option I need at least 2 IP's and I only want to use one.

In summary, I basically want to NAT a subnet to a single public address.  Any ideas?  Help would be very much appreciated

Thank you!

Ronnie

[cadet alain]

Hi,

When I enter my NAT statements with a route-map or list I only have the 
options for interface or pool.  With the pool option I need at least 2 
IP's and I only want to use one.

You can enter the same ip twice in the pool.

So to do what you want you need 2 pools and 2 ACLs

ip nat pool vlan1pool 1.1.1.1 1.1.1.1 netmask 255.255.255.255

ip nat pool vlan2pool 2.2.2.2 2.2.2.2 netmask 255.255.255.255

ip nat inside source route-map NATVLAN1 pool vlan1pool overload

ip nat inside source route-map NATVLAN2 pool vlan2pool overload

route-map NATVLAN1 permit 10
match ip address 101

route-map NATVLAN2 permit 10

match ip address 102

access-list 101 permit ip 192.168.5.0 0.0.0.255 any  (vlan 1)
access-list 102 permit ip 172.16.10.0 0.0.0.255 any  (vlan 2)

Regards.

Alain.

!

[ronnie.loraine]

Hello

Thank you very much for your assistance, however, your suggestion in this instance did not work.  I received the following error:

Router(config)#ip nat pool vlan1pool 1.1.1.1 1.1.1.1 netmask 255.255.255.255
%Pool vlan1pool mask 255.255.255.255 too small; should be at least 255.255.255.252
Router(config)#
Router(config)#ip nat pool vlan2pool 2.2.2.2 2.2.2.2 netmask 255.255.255.255
%Pool vlan2pool mask 255.255.255.255 too small; should be at least 255.255.255.252

Are there any other possibilities?

Thanks again

Ronnie

[cadet alain]

Hi,

change the netmask according to your ip addresses mask in public pool.

Regards.

Alain.

[Ganesh Hariharan]

Hello
Thank
you very much for your assistance, however, your suggestion in this
instance did not work.  I received the following error:
Router(config)#ip nat pool vlan1pool 1.1.1.1 1.1.1.1 netmask 255.255.255.255
%Pool vlan1pool mask 255.255.255.255 too small; should be at least 255.255.255.252
Router(config)#
Router(config)#ip nat pool vlan2pool 2.2.2.2 2.2.2.2 netmask 255.255.255.255
%Pool vlan2pool mask 255.255.255.255 too small; should be at least 255.255.255.252
Are there any other possibilities?
Thanks again
Ronnie

Hi Ronnie,

As Alian suggested check out the pool net mask which your are configuring as single host netmask it shoudl be a network when you are configuring nat pool.

check out the below link for nat configuration in cisco

http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080094e77.shtml

Hope to Help !!

Ganesh.H

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