Internal or External CSU/DSU
In these days, we are suffering badly due to unprotected
Saudi Telecom copper wires. The rainy season has been started. We had lost more
than 15 CSU/DSU within a week. In this environment I have learned that we
should use surge protectors/light arresters for such kind of legacy media/devices.
Also network infrastructure should be build according to the
situation, so you can minimize the loss of expensive network devices. A
conventional E1 circuit will require some type of CSU/DSU (a special type of
interface that connects the E1 from the telco demark to the serial port on your
router). You can use an internal or external CSU/DSU. Internals mean one less
thing to plug in and fewer cables to worry about. Externals can be cheaper, but
also have another advantage. In the event you experience a voltage or nearby
lightning strike to the incoming copper carrying your E1 service, the external
CSU/DSU has the potential for acting like a fuse and possibly preventing damage
to the router. With an internal CSU/DSU, the potential exists that the voltage
surge could jump right from the CSU/DSU into the router and damage it. In the
years I have been installing E1s, I have not had a situation in which the
external CSU/DSU that took damage passed the damage onto the router. As with
anything, others may have not had this type of luck.