In the below picture, there is a V.35 serial connection shown between the router and the frame relay cloud. Here are my questions and I hope someone would help me with the answers. Thanks in advance.
1) When the router is connected to frame relay via Serial cable does the router should have an inbuilt CSU/DSU?
2) Or is it that a CSU/DSU is required only when the connection goes via a T1 /E1 line?
3) If CSU/DSU is required only for T1/E1, why is it so? Why is it not required for Serial Connection?
