Hi everyone, I got a Cisco 831 router running IOS 12.4. Physically there are 5 ports which are 1 WAN (E1) and 4 LAN (FE1, FE2, FE3, FE4). When I "sh run", it shows up 7 interfaces. Besides the above 5 ports, there are E0 and E2. And my understandin...