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Ian PriceFlag for United Kingdom of Great Britain and Northern Ireland

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Cisco router can reach internet but attached switch and PC can not.

We are trying to setup some lab kit in the office real physical kit i've used packet tracer to draw out it thought, we have a  Cisco router Int 0/0 which is getting an IP address via DHCP from our internet router this is set as the outside interface for NAT. Then Int 0/1 has a static IP on this is set as the inside interface for NAT. If I ping from the router using source address (Inside interface) the ping works fine.
 We thought at first it was a routing problem, but if that was the case how would the router be able to reach the internet.
 The Nat is working as I can see the translations
 PC & Int Vlan 1 on the switch can both ping (Outside interface) but can not reach
 User generated image
 interface FastEthernet0/0
  ip address dhcp
  ip nat outside
  duplex auto
  speed auto
 interface FastEthernet0/1
  ip address
  ip nat inside
  duplex auto
  speed auto
 ip nat inside source list 1 interface FastEthernet0/0 overload
 access-list 1 permit 
 IT_Router#ping source
 Type escape sequence to abort.
 Sending 5, 100-byte ICMP Echos to, timeout is 2 seconds:
 Packet sent with a source address of
 IT_Router#show ip nat translations
 Pro Inside global      Inside local       Outside local      Outside global

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Benjamin Van Ditmars
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Benjamin Van Ditmars
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Avatar of Ian Price
Ian Price
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Yep we've put a default route in 
C is directly connected, FastEthernet0/1
C is directly connected, FastEthernet0/0
S* [254/0] via

We've not checked the router back from - We presumed it's fine becasue the router can get in and out.
all configuration seems fine but you need to check router back from

try to ping192.168.1.1 from PC , if it is working or not 

if you perform nat, the route back doesnt have to be there. i can remember something with the outside interface on dhcp and a static route. normaly he has to receive its static route with dhcp.

can you give the router a static ip on the fast 0/0 to test this

and what you can test is ip route interface fast 0/0


Networking is the process of connecting computing devices, peripherals and terminals together through a system that uses wiring, cabling or radio waves that enable their users to communicate, share information and interact over distances. Often associated are issues regarding operating systems, hardware and equipment, cloud and virtual networking, protocols, architecture, storage and management.

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