Dte And Dce Concept In Cisco Routers Need Help

[passenger67]

I have red the  definitions on the internet but i still want to know when should i  configure a DCE ? i mean DTE is configured by default in cisco routers  but why do we need to configure a DCE router give it a bandwidth and  clockrate.

is this a job of an ISP to provide DCE serivice only? or if an  organization is running a network having a lot of routers, does it  require to implement a DCE? if yes then what would be the purpose to  implement a DCE router.

[Kevin Dorrell · Accepted solution]

You are right that normally you would be a DTE, and you would connect to a modem (DCE) in your service provider.  At the other end of the link, there would be another DTE router, again connected to a service provider's modem (DCE).  The DCE provides the clock, because it is the service provider that defines the speed of the line.

What happens if you want to connect the routers back-to-back, for example in a lab.  DTE will not talk directly to DTE, so one will have to be DCE.  That is, it will have to pretend to be a service provider.  And if it is pretending to be the service provider, then it will have to provide the clock for the line.  That is one situation.

The other situatation is: what if you are a service provider, but you are not using a modem between you and the DTE customer.  In that case too, you will need to configure your router as a DCE, and provide the line clock.

Kevin Dorrell

Luxemborg

[Ganesh Hariharan · Accepted solution]

I have red the 
definitions on the internet but i still want to know when should i 
configure a DCE ? i mean DTE is configured by default in cisco routers 
but why do we need to configure a DCE router give it a bandwidth and 
clockrate.
 
 is this a job of an ISP to provide DCE serivice
only? or if an  organization is running a network having a lot of
routers, does it  require to implement a DCE? if yes then what would be
the purpose to  implement a DCE router.

Hi Murad,

A serial WAN link is a dedicated Point to Point link, mainly used to connect two sites through a telco ISP. A serial link would appear to the routers at each end to be always on. The way in which the data gets between the two routers may be very different depending on the protocol and encapsulation methods.

A DCE (Data Communications Equipment) is the equipment which the router connects to, usually provided by the ISP, and provides the main link out of an office to the ISP (in the example below, these are equipment also known as CSU/DSU's or Modem's). A DTE can only talk to a DCE, but a DCE can talk to other DCE's.

                         R1--DCE--Exchange--DCE--DCE--R2

Hope that Help !!

Remember to rate the helpful post

Ganesh.H

[passenger67]

Kevin and Ganesh thanks for your reply I really appreciated both of your answers and it really helped me a lot.