More NAT

Hey everyone,

I've got the topology above and have assigned dynamic NAT to the router illustrated. My question is how would I assign dynamic NAT on the other router? I have tried to add it on and I ping from 172.168.0.1 on the right and it goes across and gets translated and reaches the other PC but when the ping comes back the router on the left changes the source IP from 192.168.0.x to the dynamic NAT I have listed on the router.
-Then when the router on the right get's the ping it has a source on 20.0.0.x so sends it back to that router again.

I have taken my dynamic entries off of the router on the left and now everything works ok.

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Comments

networker050184

The source shouldn't make it get routed back. A router routes based on destination address, not source.

alliasneo

Hi,

I'm struggling still with this NAT set up for Dynamic NAT. I've recorded a short video which hopefully will make it a bit clearer with what I'm having problems with. Sorry about the quality but this was the quickest way to film it. I have also included my config below:

If I remove NAT completely from the router on the right then it's all OK but if I add dynamic or in this case PAT (Overload) it doesn't seem to work?

NAT Query - YouTube

Router on the left:

R1#sh run
Building configuration...

Current configuration : 1265 bytes
!
version 12.2
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname R1
!
!
!
enable secret 5 $1$mERr$9cTjUIEqNGurQiFU.ZeCi1
!
!
!
ip dhcp pool 192.168.0.0/24
network 192.168.0.0 255.255.255.0
default-router 192.168.0.254
!
!
!
username R2 password 0 cisco
!
!
!
!
!
!
!
!
!
!
!
interface FastEthernet0/0
no ip address
duplex auto
speed auto
!
interface FastEthernet0/0.10
encapsulation dot1Q 10
ip address 192.168.0.254 255.255.255.0
ip access-group 10 in
ip nat inside
!
interface FastEthernet1/0
no ip address
duplex auto
speed auto
shutdown
!
interface Serial2/0
ip address 20.0.0.1 255.255.255.0
encapsulation ppp
ppp authentication chap
ip nat outside
clock rate 64000
!
interface Serial3/0
no ip address
shutdown
!
interface FastEthernet4/0
no ip address
shutdown
!
interface FastEthernet5/0
no ip address
shutdown
!
router ospf 1
log-adjacency-changes
network 192.168.0.0 0.0.0.255 area 0
network 20.0.0.0 0.0.0.255 area 0
!
ip nat pool NAT 20.0.0.50 20.0.0.60 netmask 255.255.255.0
ip nat inside source list 10 pool CHELTNAT
ip classless
!
!
access-list 10 permit 192.168.0.0 0.0.0.255
!
!
!
!
!
line con 0
line vty 0 4
password cisco
login
!
!
!
end

Router on the right:

R2#sh run
Building configuration...

Current configuration : 1171 bytes
!
version 12.2
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname R2
!
!
!
!
!
ip dhcp pool 172.168.0.0/24
network 172.168.0.0 255.255.255.0
default-router 172.168.0.254
!
!
!
username R1 password 0 cisco
!
!
!
!
!
!
!
!
!
!
!
interface FastEthernet0/0
no ip address
ip nat inside
duplex auto
speed auto
!
interface FastEthernet0/0.20
encapsulation dot1Q 20
ip address 172.168.0.254 255.255.255.0
ip access-group 1 in
ip nat inside
!
interface FastEthernet1/0
no ip address
duplex auto
speed auto
shutdown
!
interface Serial2/0
ip address 20.0.0.2 255.255.255.0
encapsulation ppp
ppp authentication chap
ip nat outside
!
interface Serial3/0
no ip address
shutdown
!
interface FastEthernet4/0
no ip address
shutdown
!
interface FastEthernet5/0
no ip address
shutdown
!
router ospf 1
log-adjacency-changes
network 172.168.0.0 0.0.0.255 area 0
network 20.0.0.0 0.0.0.255 area 0
!
ip nat inside source list 1 interface Serial2/0 overload
ip classless
!
!
access-list 1 permit 172.168.0.0 0.0.0.255
access-list 1 permit any
!
!
!
!
!
line con 0
line vty 0 4
login
!
!
!
end

fsanyee

hm... Why are you using access-list on the interfaces?
When you create an access-list for NAT, you don't have to assign it to any interface.
If you create a nat pool with a name NAT, why are you use something else on the other line?