I currently have a Cisco 3825 router that I have (attempted) to configure. The router has two interfaces, GigabitEthernet0/0 and GigabitEthernet0/1. I would like Gi0/1 to act as my "WAN" interface while Gi0/0 acts as my "LAN" interface. The end goal is to connect the router directly to my Motorola modem, but for now, the WAN interface is connected to another router (a TP-Link TL-WR841N). The WAN interface is set up to receive a DHCP address from the router (similarly to how it would receive a DHCP address from my ISP), and is doing so successfully - the WAN interface has an IP address of 192.168.1.201 (TP-Link router is assigned the IP of 192.168.1.1).
The LAN interface of the Cisco router has an IP address of 10.0.0.1. I have a laptop connected to this interface that has a static IP of 10.0.0.2. The laptop is able to ping 10.0.0.1, but is not able to ping any external addresses (such as Google.com or 8.8.8.8). Furthermore, the Cisco router can ping the TP-Link router, but is not able to ping any external addresses either. This is my problem. My question is - how have I misconfigured the router and/or what am I missing?
I have posted the running configuration (which is the same as the startup configuration) below.
Thank you in advance!
Using 1285 out of 491512 bytes
!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname CISCO3825
!
boot-start-marker
boot-end-marker
!
enable secret
enable password
!
no aaa new-model
!
resource policy
!
ip subnet-zero
ip cef
!
!
no ip dhcp use vrf connected
!
!
no ip ips deny-action ips-interface
!
no ftp-server write-enable
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
no crypto isakmp ccm
!
!
!
!
interface GigabitEthernet0/0
description Network-facing (LAN)
ip address 10.0.0.1 255.0.0.0
ip nat inside
ip virtual-reassembly
duplex auto
speed auto
media-type rj45
negotiation auto
no mop enabled
!
interface GigabitEthernet0/1
description ISP-facing (WAN)
ip dhcp client client-id GigabitEthernet0/1
ip address dhcp
ip nat outside
ip virtual-reassembly
duplex auto
speed auto
media-type rj45
negotiation auto
!
ip classless
ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/1
!
!
no ip http server
no ip http secure-server
ip nat inside source list 10 interface GigabitEthernet0/1 overload
!
access-list 10 permit 10.0.0.0 0.255.255.255
!
!
!
!
control-plane
!
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!
!
!
!
!
!
!
!
line con 0
exec-timeout 0 0
stopbits 1
line aux 0
stopbits 1
line vty 0 4
password
login
!
scheduler allocate 20000 1000
!
end
I resolved this issue by changing the ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/1 route to ip route 0.0.0.0 0.0.0.0 dhcp, which promptly allowed me to ping external IP addresses. I discovered this solution after enabling detailed packet debugging through the debug ip packet detail command, which showed me that when I attempted to ping 8.8.8.8, I was receiving an "Encapsulation Failed" error. A brief amount of research afterwards led to my discovery that I needed to change my route.
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