Dte/dce

[learn25]

Hi all.

I'd like to know if in the actual ("real world") WAN implementation of connecting serial interfaces of routers we do have situation where we need to configure the other end as DTE and the other one as DCE and configure the clock rate? Are there situation where we don't have to use CSU/DSUs?

Also, I'd like to know if things such as E1, T1, Frame Relay, ATM, SDH, SS7, etc. are physical devices or just a form of "communication standard".

Kindly enlighten me about this.

I asked this because during my school days we were taught in our subject Data Communications regarding these technologies including things such as Line Coding, PCM, QAM, Bit Error Rate, OSI etc. But things are unclear. We just memorize but do don't have good understanding. Its only now when I read Lammle's book where I can differentiate where those different technologies belong in a specific layer of the OSI model. And its only now that I'm enlightened about the role of the OSI model in the field of Data Communications.

Thank you.

[lammle]

If you are using the clock rate command on a serial interface in production, something is wrong. It would be a very rare situation where you would need this.

Any serial interface can handle multiple WAN data link protocols like HDLC, SDLC, Frame Relay , T1/E1 and PPP - all of these would need a CSU/DSU - and this device is what provides clocking to your router.

For some of the others you mentioned, they need a special interface, like ATM and ISDN (SS7 is the clocking technique use on the D channel).

The line coding you mentioned is the clocking and syncronziationtechniques used at the physical layer that is used on the various lines to communicate to the CO. The CSU/DSU, again, provides this.

So, no worries about clocking in production.

Cheers!
Todd Lammle

[learn25]

Thank you very much! :D