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New Member

CCNA lab questions

As the first student in semester 2 of our school I have the honor ( or horror ) of setting up our labs.

We are working with 2500 series routers.

I went through the setup routine ok but received line protocol down messages on all interfaces. After a lot of hair pulling I discovered by setting the clock rate on each interface it works.

My questions are, is this normal? If so why isn't it a part of the set up routine?

Also, is there a more appropriate place for me to post CCNA lab questions?

6 REPLIES
New Member

Re: CCNA lab questions

The easiest way to keep the lines up is to go into the acutal interfaces such as int e0 and type the command no shutdown. This will keep the line protocols up.

New Member

Re: CCNA lab questions

normally a serial interface must be attached to a modem that will supply clock rate. if you don't use a modem (but you use a back to back serial cable) then you must configure the clock rate in the serial interface in wich dce cable is connected.

New Member

Re: CCNA lab questions

In a lab environment, it's very normal to have to do so. I am also a CCNA student but I'm in semester 3. You configure all your routers to be like in the lab topology and then you have to specify the clock rates for all serial interfaces and issue the no shutdown command to all interfaces.

I think here's the best place for CCNA talk.

Good luck, if you have any more questions about the semesters, you can ask me.

David Coronel

dcoronel82@hotmail.com

CCNA student, Lasalle College

New Member

Re: CCNA lab questions

Yes, this is normal in a lab environment. In real networks, the serial interfaces will be connected to a communication equipment (like modem, CSU/DSU etc) In this case, the clock will be supplied by these communication equipment.

But in the lab environment, most of the time we connect two routers back-to-back to simulate a WAN connection. In that case one of the routers must supply a clock to the connection. Usually it is the router at the DCE end of the cable that will supply the clock. To find out which router has the DCE end of the cable, issue the "show controllers" command and the output will show if the cable end connected to the interface is DCE or DTE.

Good Luck

Mohan

New Member

Re: CCNA lab questions

An easier method is to look at the cable. The v.35 serial cables will always be as follows: Male ends (cable with pins outward) is the DTE, Female cable (pin holes) is the DCE. The DCE gets the clockrate. Or you can simply set clockrate on both routers it will only use it on the router with the DCE attached.

New Member

Re: CCNA lab questions

When setting up serial interfaces in a lab environment, you always need the clockrate setting on the DCE end of the connection. If it wasn't specified in the lab setup documentation, either it was an oversight or the instructor was creating a bug for you to figure out.

You might want to try the Career Certifications area to post CCNA questions....just a thought.

By the way - your profile shows you as a CCIE (or am I misreading it?).

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