Physical layer signalling in Cisco router serial interface

[shyam111]

Hi All

I am very much confused about the various control signals in the serial port(V.35) of the router.Like DCD RTS CTS etc etc.

I want to know how exactly these signals r used and how it can be helpfull in troubleshooting the serial interface of the router.

Also in most cases we use V.35 serial interfaces but offlate i have seen some other interfaces as well like X.21 RS 530 V.36 .And they all seem to have the same cortrol signals like V.35.Then what is the difference between then and which is suited for which application.

Please help me out.
If there is any good resource in the internet then please let me know.

Thanks
shyam