NAT on router with only ip nat outiside role

Unanswered Question
Oct 24th, 2008


I'm wondering for the following behaviour.

My router Cisco 1841 IOS 12.4(21) has the following config:

interface FastEthernet0/0

ip address

duplex auto

speed auto


interface Serial0/0/0

bandwidth 2048

no ip address

encapsulation frame-relay IETF

no ip mroute-cache

load-interval 30

no fair-queue

frame-relay lmi-type ansi


interface Serial0/0/0.70 point-to-point

ip address

ip nat outside

frame-relay interface-dlci 70


ip nat outside source static

As you can see there's not the “ip nat inside” statement.

If I do the command:

#telnet 80 /source-interface fastEthernet 0/0

Trying, 80 ... Open

*Oct 24 15:55:31: NAT: s=, d=> [47828]

*Oct 24 15:55:31: NAT*: s=>, d= [9352]

#sh ip route

Gateway of last resort is to network is variably subnetted, 4 subnets, 2 masks

C is directly connected, FastEthernet0/0

S* is directly connected, Serial0/0/0.70

I'm wondering why the translation happens!!!

Can anybody clearify ?



I have this problem too.
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rais Fri, 10/24/2008 - 06:20

Once you have specified the nat outside interface it is sufficient for NAT to start working. You omit outside definition and it would stop working.


Davy Ad Thu, 11/06/2008 - 04:55

I think it would be better to use the nat outside interface " " as the static nat instead.




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