DTE and DCE serial connections

Techytach

So my computer would be a DTE connection, and my modem a DCE.

Basically I am the DTE and my ISP is the DCE (I think I get the basics.)

In labs however we seem to simulate WAN connections overly simplified by two routers on a serial connection with a DTE and a DCE end.

My question is in a real network, with several routers, vlans, lans, etc. You wouldn't have dte/dce connections between those routers right? Is it possible to have a serial connection between routers with no dte/dce? Or in a real network do you just use ethernet connections? Only one of those routers (leading to the ISP) would have that dte/dce connection right?

I'm confused. I hope this makes sense.

pinkiaiii

your jumping too far :] since guess you just started with ccna youll learn about WANs or not depending when is your exam

but to make it simple serial is used for frame relay,ppp,hdlc thus to connect networks that are far away, that it would seem like your working in same network if that makes sense,wide area networks thus like between two cities etc.

In real world say if you work in single building you wouldnt ever need to set dce clock or use serial cable,just normal ethernet cables and trunks and encapsulations on router.And even if using some wan protocol most would be set up by ISP,thus in many cases even configurations on user end are done by hired company.Take a note that from august 20th there wont be frame-relay topic in ccna.

Techytach

your jumping too far :] since guess you just started with ccna youll learn about WANs or not depending when is your exam

No need to make an aSSumption.

I have my ccent about to take icnd2. I just have no work experience, only lab. In my labs all the routers were connected through serial connections AND ethernet. Hence the confusion. They never explained it was unusual.

I have till September 24th I think to take the old icnd2. August is for icnd1 I think.

james43026

A serial connection is just like an ethernet connection in many ways. One of the main differences though is that a clock rate is needed, and one device needs to provide that clock rate, which is the DCE, also the different ends of a cable are wired differently as far as the pinouts are concerned. DTE and DCE was where the concept of MDI and MDIX really shines. In a real environment, if you were using lets say a T1 line, your telco would run a T1 line into your building and connect it to a NIU / Smartjack which will contain line cards from the telco, the NIU will then connect to your demarc which will be a patch panel, that has RJ-48C ports on it. that you would connect to either a dedicated CSU/DSU, or most WIC and HWIC cards have a built in CSU/DSU. Frame relay can be delivered in similar ways, as frame relay is most often delivered with a T carrier line.

Techytach

james43026 wrote: »

In a real environment, if you were using lets say a T1 line, your telco would run a T1 line into your building and connect it to a NIU / Smartjack which will contain line cards from the telco, the NIU will then connect to your demarc which will be a patch panel, that has RJ-48C ports on it. that you would connect to either a dedicated CSU/DSU, or most WIC and HWIC cards have a built in CSU/DSU. Frame relay can be delivered in similar ways, as frame relay is most often delivered with a T carrier line.

Thanks.

Is there ever a real world scenario where one would connect via serials on a LAN? Perhaps for security reasons?

edit: reading the thread about the test dropping wan tech, I am realizing serial stuff is old tech. Becoming more clear.

james43026

Serial connections are pretty much out the door. You would use ethernet and or fiber pretty much everywhere in your network. Serial is really only used for legacy reasons, like getting a T1 line from a carrier, and they only support installing a CSU/DSU that only supports a serial interface for you to use.

shanetech74

The DTE/DCE are now built into the CSU/DSU -> google DCE DDTE pic for a picture of the connectors. ... Today the telco will terminate the t1 into a smartjack. You plug a cat 5 into the smartjack and csu/WIC.