CSU/DSU and DCE

[Ahmed Malik]

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. What i dont understand is that are CSU/DSU and DCE the same device because they both provide clocking or they both are different?

Other thing is that DCE device is usually at the service provider side so it means that we home users are first connected to a CSU/DSU box and then at the service provider they connect to DCE and both CSU/DSU provide clocking so is the data also clocked at the DCE before entering the WAN?

Thanks,

Ahmed

[vmiller]

DSU/CSU is a DCE  (generic term) that provides the transition to the Telco service. DSU handles the interface with the DTE and CSU handles the interface with the telcom service.

[Peter Paluch]

Hello Ahmed,

In addition to the vmiller's answer, I would like to correct a slight misinformation. You wrote:

Other thing is that DCE device is usually at the service provider side

As far as my knowledge goes, this is not correct. The DCE device is still at the customer's premises, usually connected to the customer's edge router via a short cable, and subsequently connected to the local loop provided by the telco. There is another DCE component at the other end of the local loop, and the two DCEs - the one at the customer's premises, and the other at the ISP - talk to each other directly. Between two routers, the interconnection is DTE-DCE-DCE-DTE.

Best regards,

Peter

[Odys (CSC)]

I find both answers very helpful. short and to the point, comparing with this thread:

https://learningnetwork.cisco.com/thread/28073

[Peter Paluch]

Hello Hydir,

Thank you very much!

Best regards,

Peter

[muzazamubika12]

hi...

does anyone know what command for setup this dte at router?

[vmiller]

Here is an example for frame relay using a router as a frame relay switch.

http://www.cisco.com/en/US/tech/tk713/tk237/technologies_configuration_example09186a0080094a3c.shtml

back to back HDLC

http://www.cisco.com/en/US/tech/tk713/tk317/technologies_configuration_example09186a00800944ff.shtml

what are you trying to accomplish ?