I am having difficulty connecting these two routers back to back, via a T1 cable. The hardware is a WIC-1DSU-T1= in each device. The problem is, I cannot get the line protocol to come up.
The encapsulation is ppp on both ends
Both ends are using esf framing
Both ends are using a line code of b8zs
Both ends have a clock source of line
the 3640 has the "no-dce-terminal" command
the 2621xm has a clock rate of 4000000
Neither side has alarms that I can see
The cable I made is correct, it works when connecting 2621xm to 2621xm and 3640 to 3640. It does not work when going from 2621xm to 3640.