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Community Member

Serial Interface signalling terms

What are CDC, CTS, RTS, etc, which we see when execute show int s0 command ?

What is their importance in determining the status of the serial interface?

How they aid in troubleshooting a serial link?

Community Member

Re: Serial Interface signalling terms

cdc means carrier detect,and cts means clear to sent. rts means request to send. From the status of these physiical signal,we can infer that if there is something wrong with the serial interface,or it's the dte or dce that cause the situation.You can troubleshoot physical layer problem of a serial link according to them.

Community Member

Re: Serial Interface signalling terms

Your explanation is superficial!

I want to know exactly that suppose if CDC is down what should the cause and how to fix that ....and like other terms .....?

Community Member

Re: Serial Interface signalling terms

In most communications protocols you will find five control leads. They are DCD (data carrier detect), RTS (request to send), CTS (clear to send), DTR (data terminal ready), and DSR (data set ready). RTS and DTR belong to the DTE device and DCD, DSR and CTS belong to the DCE device. All of these leads are between the DTE and the DCE. Most devices have options that can be set to control the use of these leads, so my answer here will concentrate on the most common situation.

When a DTE device is powered on and passes its self test, it will raise DTR and in most cases RTS. This indicates that the DTE device is ready to send and is requesting the right to do so. When a DCE device (CSU/DSU maybe) are powered on, it also will self test. If this self test passes, it will raise DSR and attempt to communicate with the DCE at the other end. They do this by raising carrier on the circuit (T1 maybe). When the local DCE detects carrier from the remote, it will raise DCD and (usually) CTS toward the DTE. At this point, all five leads have been raised and, assuming the same condition at both ends, communication can proceed.

One other thing: I don't think that you treated the previous respondant fairly when you said, "Your explanation is superficial!". You should be happy to recieve any answer left in good faith. The people that answer your questions have spent a lot of their own time and money learning these things. They are not required to answer your questions. If you don't like the answers that you receive here, I would suggest that you spend some time (and several thousand dollars for a class) to learn basic communications.

Community Member

Re: Serial Interface signalling terms

I am extremely very sorry that my words hurt your feeling.

I am also very greatful to you that you send such a valuable knowledge to me.

Basically, I read out some of these things in some books but I wanted the clear understanding since I am preparing to go for CCNP certification.

I hope your generous response will continue

Thanks and Regards


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