I am using cisco 2811 router with 1 WIC-1T card for serial interface Both router is connected by serial (DCE/DTE) interface and and ip is set as follows: router 1: 192.168.1.1 255.255.255.0 router 1: 192.168.1.2 255.255.255.0 Problem: line protocol is showing down . Example bellow : R1#show ip interface brief Interface IP-Address OK? Method Status [...]