troubleshooting Question

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

Avatar of Ian Price
Ian PriceFlag for United Kingdom of Great Britain and Northern Ireland asked on
CiscoNetworkingPC
4 Comments1 Solution22 ViewsLast Modified:
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 192.168.1.81 this is set as the outside interface for NAT. Then Int 0/1 has a static IP on 192.168.10.254 this is set as the inside interface for NAT. If I ping 8.8.8.8 from the router using source address 192.168.10.254 (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 192.168.1.81 (Outside interface) but can not reach 8.8.8.8
 
 Diagram

Description automatically generated
 interface FastEthernet0/0
  ip address dhcp
  ip nat outside
  duplex auto
  speed auto
 
 interface FastEthernet0/1
  ip address 192.168.10.254 255.255.255.0
  ip nat inside
  duplex auto
  speed auto
 
 ip nat inside source list 1 interface FastEthernet0/0 overload
 !
 access-list 1 permit 192.168.10.0 0.0.0.255 
 
 
 IT_Router#ping 8.8.8.8 source 192.168.10.254
 
 Type escape sequence to abort.
 Sending 5, 100-byte ICMP Echos to 8.8.8.8, timeout is 2 seconds:
 Packet sent with a source address of 192.168.10.254
 !!!!!
 
 
 IT_Router#show ip nat translations
 Pro Inside global      Inside local       Outside local      Outside global
 icmp 192.168.1.81:29   192.168.10.254:29  8.8.8.8:29         8.8.8.8:29
 icmp 192.168.1.81:30   192.168.10.254:30  8.8.8.8:30         8.8.8.8:30
ASKER CERTIFIED SOLUTION
Benjamin Van Ditmars
Sr Network Engineer

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