Question : Cisco Router Secondary Ethernet

I have a Cisco Router with an address on the Fast Ethernet Port.
I want to allow another network to pass through the same router, so I assigned
a secondary address on the FastEthernet port. I can ping the secondary address from outside, but I cannot ping any computer on the local lan with using the secondary block. I cannot ping the fast ethernet port from the local lan using the secondary block..

I want DETAIL instructions to remedy...

Answer : Cisco Router Secondary Ethernet

If your Ethernet port looks like this:
!
Interface Ethernet 0/0
 ip address 192.168.122.1 255.255.255.0 secondary
 ip address 10.1.1.1 255.255.255.0
!

As long as your workstations that are assigned to the secondary subnet of 192.168.122.x have the correct subnet mask, and the router's interface as their default gateway, all should work fine.

If you still have problems, post your existing config.