Hi, I hope this is the right board, but the WAN topic didn't really fit either :)
We were assigned a range of IPs from our ISP. To be exact, there are 8 IPs, where 1 is the network address, 1 is the gateway and one is the broadcast address. That basically makes 5 useable addresses.
Now my question. How do I configure one physical interface with multiple IP addresses?
I tried assigning the addresses to subinterfaces of that physical interface but I received the message that the line has to be configured as a trunk line. Now, is that line a trunk line by default? Since the other end of the cable is plugged into a port of the ISPs device (4 DSL cables end there as well). Until now we have only been using just one address (and the gateway) but we would like a server in our network to have a IP address of its own.
Thanks for any responses.
I am using a Cisco 1811 running IOS 10.4
The router knows which interface because of the "ip nat inside" and "ip nat outside" statements in your configuration. So on your outside interface
ip address 184.108.40.206 255.255.255.248
ip nat outside
As i say 220.127.116.11 must be routed back to the outside interface (fa0/1) of your router when traffic returns from the Internet but that is what the ISP does. They allocate you a /29 subnet and make sure that any traffic for IP addresses in that subnet are routed to your router.
Edit - just to clarify. The router knows which interface to send the packets out of due to it's routing table. So it consults it's routing table to find out how to get to the destination address and then when it routes it out of the fa0/1 interface it then gets natted because of the "ip nat outside" statement.
Apologies for any confusion.