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Again we want to see the show interface serial 0 command report that the interface
is up and the line protocol is up. First, what will happen if the
serial interface on router 3 is disconnected from the local CSU/DSU?
The interface reports down and the line protocol also reports a down
state. We also see that the EIA signals DCD, DSR, and CTS disappear.
EIA signals are either generated from the router interface or the
CSU/DSU device. In this case, the CSU/DSU generates DCD (carrier
detect), DSR (data set ready), and CTS (clear to send). If these
signals are not present, we know that the cable between the
interface and the CSU/DSU is disconnected, or that the CSU/DSU is
powered off. |
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