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New Member

NAT Trouble

Hi everyone I am having an issue configuring NAT on my router.

my inside network is /24

my outside network is

I want a NAT pool that translates 10.10.10.? into for access to the internet, the serial interface on my router is the network and the Ethernet int is the network. please help with this.

Hall of Fame Super Blue

Re: NAT Trouble


The following config will achieve what you want. One thing though, are you sure the inside LAN is on your serial interface and the outside interface is the ethernet interface ?

If you have got that the wrong way round just modify the following config. Should be failry obvious what needs changing.

ip nat inside source list 101 interface e0 overload

access-list 101 permit any

int s0/0

ip nat inside

int e0

ip nat outside


New Member

Re: NAT Trouble

ok first jon your a legend, I could only aspire to be as good as you some day, thanks.

I have created my own network at home,

the router that faces the internet is /24 and it has a DHCP pool for the whole subnet, I have an cat 5 from a port on the router to my 1900 switch and another cat 5 from a port on my switch to the e0 on my 2500 router, its ip is, now on the serial link from the 2500 the network is this is connected to another 2500 router, the ethernet 0 int on this 2500 is /24, i have configured nat on this router to translate the 173 network into the serial interface but when the ping to gets to the int ser 0 of router 1 it can go no further, it just times out, so need to be able to ping from 173.? to, can i do this?

Hall of Fame Super Blue

Re: NAT Trouble


"ok first jon your a legend, I could only aspire to be as good as you some day, thanks"

Hmmm, i think you should aspire to something a little bit better than that... :)

Does your setup look like this

Internet - router1 ( - ( 2500_1 (s0 - 10.10.10.?) - (s0 - 10.10.10.?) 2500_2(e0 -173.135.168.?)

If you are Natting all the 173.135.168.x addresses to 10.10.10.x 2500_2 then does router1 have a route for the 10.10.10.x network pointing back to 2500_1.

If not and you can't add a route to router1 then you could move the Nat to 2500_1 instead of on 2500_2 and then the 173.135.168.x addresses would be natted to Router1 would know how to get to this address.


New Member

Re: NAT Trouble

OK after a weekend of trying until the early hours I found the issue, the router I have as the internet facing router is ISP supplied and when I try to ping 173.135.168.X the ISP router bounces the packet into the internet instead of routing in into the internal network. I cannot configure a static route on this “Router” so I have bought a Cisco 837 ASDL VPN router from E-Bay so fingers crossed this works for me. Thanks for your help