CSU/DSU and DCE Quesion

[typesh]

Hey everyone,

I am having some problems understanding the CSU/DSU and DCE. I understand that a CSU/DSU is used to connect a DTE (such as a router or computer) to a T1/T3 line. From what I understand, the DTE connects to the CSU/DSU box, and then the CSU/DSU box connects to the circuit. I am a little confused in how that differs from a DCE. I am not really sure on what a DCE is. I understand from Page 30 of Lammle 6th Ed that the DCE is usually located at the service provider. I have researched it online and to me is sounds very similar to a CSU/DSU.

Wikipedia says: A Data circuit-terminating equipment (DCE) is a device that sits between the data terminal equipment (DTE) and a transmission circuit.
It also says that the DCE is a modem.

I though it was the CSU/DSU that sits between the DTE and Transmission Circuit, and I thought the CSU/DSU was the modem.

This has been really confusing...

Any help would be appreciated.

Thank you.

[lildeezul]

Yep, a DCE provides clocking, and the CSU/DSU also provides the clocking.... The service providers DCE is usually the CSU/DSU...

In the enterprise over here, they have their routers (DTE) connected to the jack, which is the Demarc point, and the Service providers CSU/DSU provides the clocking rate and ect, so the DTE device.

[typesh]

Thank you! This has been really confusing...

If I understand correctly....

The router (DTE) connects to a CSU/DSU which actually is the DCE?

So, would it be correct to say a CSU/DSU is the DCE, and that they both can be referred to as a modem?

[lildeezul]

yep,, thats why in lab environments, you have to have one router the DCE which provides the clocking , which is basically substituting the CSU/DSU

[typesh]

Sounds good! It makes sense now.

Just wanted to clarify the word "clocking."

Does clocking tell the DTE how many bits to send and receive per second?

For example:

When using the "clock rate ?" command, are we telling the DTE how many bits per second to send, or to receive?

[crissa]

[...]

When using the "clock rate ?" command, are we telling the DTE how many bits per second to send, or to receive?

Hello,
always remember: DCE => Do Clock Enable

You have to set the clock rate on the DCE end. Usually only in a lab, where else you have to take care of the DCE equipment?! :-)
Bye, Tore

[typesh]

If i set the clock on the DCE Router like this:

clock rate 64000

Is that telling the DCE how many bits per second to send/receive?

[lildeezul]

From my conception yes, the clock rate is basically the CIR, if running frame-relay, that the SP provides to you...

but yep 64000 = 64kps

[typesh]

Thanks guys!