T1 to Ethernet handoff

[JoseQuijano2604]

Hi everyone. 

I'm using a Cisco 1921 with a VWIC2-2mft-t1/e1 to convert a T1 handoff from the ISP to a single ethernet. 

I configured the T1 and is up, from the router I have internet access(i can ping 8.8.8.8). on the Gigabitethernet 0/0 I have a computer and configured a DHCP server on that port with 10.10.10.0/25. also, I have the default static route pointing to the serial interface.

The problem I'm having is that from the computer I cannot connect to the internet. I'm able to ping only 10.10.10.1 but cannot ping the next hop 4.25.115.102. I attach both my config and static routes. I've tried different static routes but I cannot make it work.

Thank you for any help in advance and let me know if you have any other questions. 

[Filip Knezevic]

So can you ping 8.8.8.8 from the router itself, not the PC behind LAN?

[Filip Knezevic]

I noticed your have default gateway, not ip route 0.0.0.0. Def Gateway is used for switches.

Can you remove your ip default-gateway 4.25.115.102 and insert ip route 0.0.0.0 0.0.0.0 4.25.115.102 instead?

[JoseQuijano2604]

Thank you for info,
I made the change, removed the IP default-gateway and added the route but still im not able to ping from the computer even 4.25.115.102.

[JoseQuijano2604]

Correct I can ping 8.8.8.8 from the router but not from the computer. 

[Filip Knezevic · Accepted solution]

You don't have NAT.

Paste these commands:

ip access list standard NAT
permit 10.10.10.0 0.0.0.127

ip nat inside source list NAT interface Serial0/0/0:0 overload

interface GigabitEthernet0/0
ip nat inside

interface Serial0/0/0:0
ip nat outside

It should work.

[Richard Burts]

It is true that the original config did include ip default-gateway. And it is true that this command is not used if ip routing is enabled. But that does not necessarily indicate that the command should be removed. Because the original config also included an ip route 0.0.0.0 0.0.0.0n serial 0. So the routing in the original config was ok. And that is why the router was successful in ping 8.8.8.8. @Filip Knezevic is quite correct that the significant issue is that the original config did not include address translation. 

HTH

Rick

[Filip Knezevic]

Hi Richard,

Thanks for the observations. Indeed I missed there was an ip route command as I was in a hurry.

But definitely his issue is that there is no Port Address Translation configured.

I still think it's not bad that the the unnecessary ip-default gateway command was removed, though it wouldn't break anything if he left it. 

[JoseQuijano2604]

Thank you for your help Filip,
I tested what you mention, the issue is resolved.

[Filip Knezevic]

Hi Jose,

Glad it's working.