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Community Member

Simple Routing Issue

Afternoon Everyone,

Appologies for such a basic question but i'm just getting started with cisco kit so you will have to bare with me.

I have a cisco 1841,

Fa0/0 has the ip of 192.168.5.20

Fa0/1 has the ip of 10.0.0.1

Fa0/0 goes off to the Default gateway of 192.168.5.254

Fa0/1 goes off to a switch where I have a test machine connected (Ip 10.0.0.5).

From the router I can ping 8.8.8.8 for example and it's fine.

From the test computer I am unable to.

I added the "ip route 0.0.0.0 0.0.0.0 192.168.5.254" which then allow the router to ping 8.8.8.8

I realise I am probably making a very basic mistake but would appriciate some points or hints as to where I am going wrong.

Below is the config:

Password:

R1#show run

Building configuration...

Current configuration : 847 bytes

!

version 12.4

service timestamps debug datetime msec

service timestamps log datetime msec

no service password-encryption

!

hostname R1

!

boot-start-marker

boot-end-marker

!

enable secret 5 $1$wssO$VhBou3PyVzg.IbEz4.4xv/

!

no aaa new-model

!

resource policy

!

mmi polling-interval 60

no mmi auto-configure

no mmi pvc

mmi snmp-timeout 180

ip subnet-zero

ip cef

!

!

no ip dhcp use vrf connected

!

!

no ip domain lookup

!

!

!

!

interface FastEthernet0/0

ip address 192.168.5.20 255.255.255.0

duplex auto

speed auto

!

interface FastEthernet0/1

ip address 10.0.0.1 255.255.255.0

duplex auto

speed auto

!

ip classless

ip route 0.0.0.0 0.0.0.0 192.168.5.254

!

no ip http server

!

!

control-plane

!

!

line con 0

line aux 0

line vty 0 4

password test

logging synchronous

login

line vty 5 15

password test

logging synchronous

login

!

end

If anyone could help that would be greatly appriciated.

Am I right in thinking I would have to create some sort of NAT rule from the inside to outside. or am I going down the wrong path here

Everyone's tags (2)
1 ACCEPTED SOLUTION

Accepted Solutions
Purple

Simple Routing Issue

Hi,

yes you're right, just do NAT and it shall work:

access-list 1 permit 10.0.0.0 0.0.0.255

ip nat inside source list 1 interface f0/0

int f0/0

ip nat outside

int f0/1

ip nat inside

Regards.

Alain.

Don't forget to rate helpful posts.
3 REPLIES
Purple

Simple Routing Issue

Hi,

yes you're right, just do NAT and it shall work:

access-list 1 permit 10.0.0.0 0.0.0.255

ip nat inside source list 1 interface f0/0

int f0/0

ip nat outside

int f0/1

ip nat inside

Regards.

Alain.

Don't forget to rate helpful posts.
Community Member

Simple Routing Issue

Thank you for your fast reply alain.

Just to get this correct so I understand, all we have done here is effectively called fa0/0 outside and 0/1 inside.

A new access list has been created for the network 10.0.0.0

We have then told the router that if any traffic from the inside interface in list 1 matches 10.0.0.0 to send it to the outside interface 0/0

Purple

Simple Routing Issue

Hi,

any source address matching access-list 1 entering the inside interface will get translated to the IP address of the outside interface along with a port number so this is called NAT overload( many to one). So from the outside the source IP is the outside IP.

Regards.

Alain

Don't forget to rate helpful posts.
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