Introduction to Cisco Show Controllers Command

The cisco show controllers command displays full information about the physical interface of a cisco router itself.

Cisco Show Controllers Command helps to indicate the type of serial cable plugged into a serial port.

Typically, there  will only be a DTE cable, which then plugs into a type of Data Service Unit (DSU).

For instance the show controller 0 displays the following information below:

Router#sh controllers s 0

 HD unit 0, idb = 0x1229E4, driver structure at 0x127E70

buffer size 1524 HD unit 0, V.35 DTE cable

cpb = 0xE2, eda = 0x4140, cda = 0x4000

The show controller S 1 displays the following  information on the router

Router#sh controllers s 1

 HD unit 1, idb = 0x12C174, driver structure at 0x131600

buffer size 1524 HD unit 1, V.35 DCE cable

cpb = 0xE3, eda = 0x2940, cda = 0x2800

Notice that serial 0 has a DTE cable, whereas the serial 1 connection has a

DCE cable. Serial 1 would have to provide clocking with the clock rate

command. Serial 0 would get its clocking from the DSU.

Meanwhile, it is good to understand that this is the only command that needs to have a space after the command serial.

Router#sh controllers s1


% Invalid input detected at ‘^’ marker.

with this a anyone taking cisco ccna will be able to identify all controllers information in his router.


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