NAT issues, basic setup

[BarnesUK]

Hello,

i'm going through my ICND1 right now and i'm setting up my 1841 router to replace my current netgear router.
the netgear i'm setting to modem mode, and the 1841 with be my main router. The ip from my ISP is more than likley dhcp, but i'm not worried about that as i only want
to test everything to see if i can get it to work.

ISP
IP: 205.178.28.138
SN: 255.255.255.248
GW: 205.178.24.1
i have the isp DNS and have set it up in dhcp. i've also tested with googles public dns

i've set up dhcp on the 1841 itself and it's working. i'm able to see the IP it gave out in the binding and can ping between my router and PC.

i believe i've setup NAT correctly and applied ACL correctly, but i can't get out to the internet. i can't even ping 8.8.8.8 from the router itself, as some suggested i should be able to do.

if anyone wouldn't mind taking a look at my config, i'd really appreciate it.

Thanks

Jaime

Current configuration : 1175 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
!
!
no aaa new-model
!
!
!
!
ip cef
!
!
no ip dhcp use vrf connected
ip dhcp excluded-address 192.168.0.1 192.168.0.5
!
ip dhcp pool DHCP
network 192.168.0.0 255.255.255.0
default-router 192.168.0.1
dns-server 208.59.247.45 208.59.247.46
!
!
!
multilink bundle-name authenticated
!
!
archive
log config
hidekeys
!
!
!
!
!
interface FastEthernet0/0
ip address 192.168.0.1 255.255.255.0
ip nat inside
ip virtual-reassembly
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 205.178.28.138 255.255.248.0
ip nat outside
ip virtual-reassembly
duplex auto
speed auto
!
interface Serial0/0/0
no ip address
shutdown
!
ip route 0.0.0.0 0.0.0.0 205.178.24.1
!
!
ip http server
no ip http secure-server
ip nat inside source list NAT interface FastEthernet0/1 overload
!
ip access-list standard NAT
permit 192.168.0.0 0.0.0.255
!
!
!
!
!
!
!
control-plane
!
!
!
line con 0
logging synchronous
line aux 0
line vty 0 4
login
!
scheduler allocate 20000 1000

!
webvpn cef
end

[rasmus.elmholt]

Hi
Is it really a /21 network on the WAN interface. In your description you mention a /29 network.
Are you able to ping the default gateway(205.178.24.1) from the router?

You NAT configuration is by the book, and should be working.

[Reza Sharifi]

Hi,

Looking at the public IPs  below, your side and the ISP side IPs are not in the same subnet.

Can you check and verify the correct IPs?

IP: 205.178.28.138

SN: 255.255.255.248

GW: 205.178.24.1

HTH

[BarnesUK]

Thanks for getting back.

i'm going to double check the ip's, once i change the netgear router back to modem.

[Reza Sharifi]

Yes, there is definatly something wrong with the address scheme.

HTH

[BarnesUK]

i just set netgear back to modem mode and retrieved the ip's

Connection-specific DNS Suffix . : cable.rcn.com
Link-local IPv6 Address . . . . . : fe80::355b:d867:539c:fd6c%4
IPv4 Address. . . . . . . . . . . : 205.178.28.138
Subnet Mask . . . . . . . . . . . : 255.255.248.0
Default Gateway . . . . . . . . . : 205.178.24.1

[BarnesUK]

i've just set my netgear back to router mode and looked at the source ips within the netgear and i see a new ip's

Netgear
IP 205.178.39.186 /20
GW 205.178.32.1

i plugged the new info into the 1841 and still no go. i think it may have something to do with ip's on the ISP's side.

Thanks for the help so far.

[Reza Sharifi · Accepted solution]

You may want to call RCN and ask them for the subnet they assigned to you.

Usually the provider does not give a small customer a /20

HTH

[BarnesUK]

Sounds about right, thanks again.

[rasmus.elmholt]

Hi

Have you tried looking for PPPoE configuration on the netgear?

There could be a PPPoE setup somewhere.