Computer Software

When you’re preparing for success on your CCNA or CCNP certification exams, sooner or later you’re going to want to start totally from scratch on your Cisco routers and switches. It’s easy enough to type “write erase” and “reload”, but there are a few details you have to watch if you want your home lab or rack rental devices to act as though they just came out of the box.

The first step is indeed to run the command write erase, and then reload the router. You’re going to be prompted with a question before the reload starts, though, and you have to give the right answer …. or your configuration will still be there when you reload!

First, you will be prompted to confirm the erase. Press to accept the default answer of “confirm”.

R1#write erase

Erasing the nvram filesystem will remove all configuration files! Continue? [confirm]

[OK]

Erase of nvram: complete

With the startup configuration erased, it’s time to reload the router. This is where the second prompt comes in:

R1#reload

System configuration has been modified. Save? [yes/no]: no

When a Cisco router prompts you with two answers to a question, you’ve got to type the answer in (or at least the first letter of it). Answer NO to this question and press when prompted to confirm the reload.

The router will then start the reload process. Since there is no startup configuration in NVRAM, the router will prompt you to enter setup mode. You should only answer yes if you have a lot of time on your hands, just want to see what setup mode is like, or practice CTRL-C to get out it! Otherwise, answer NO.

— System Configuration Dialog —

Would you like to enter the initial configuration dialog? [yes/no]: n

Would you like to terminate autoinstall? [yes]:y

You’ll see quite a few messages after this relating to interface states, and finally you’re back at the user exec prompt.

Router>

Now you’re working with a router that’s just like it was when it came out of the box!

For switches such as the 2950, the process is much the same, but you should delete the VLAN.DAT file before reloading the router. This file contains VLAN information and is kept in flash, so it will still be present after a reload.

switch1#write erase

Erasing the nvram filesystem will remove all files! Continue? [confirm]

[OK]

Erase of nvram: complete

switch1#delete vlan.dat

Delete filename [vlan.dat]?

Delete flash:vlan.dat? [confirm]

switch1#reload

Make sure to hit for the two questions regarding the deletion – if you answer “y” instead, the switch thinks you’re trying to erase a file named “y”!

After the reload is complete, you’ll be prompted to enter setup mode. As you did with the router, enter “N” and begin to configure the router from user exec mode. There’s nothing like working with real equipment to prepare for your CCNA and CCNP success, and there’s no better practice than configuring routers and switches from the very beginning!

More CCNA and CCNP candidates than ever before are putting together their own home practice labs. It’s more affordable than it ever has been, and I receive emails daily from new CCNAs and CCNPs who say it’s the best thing they could have done to improve their studies.

There are some commands you can configure on your lab routers that won’t necessarily be on your CCNA or CCNP exams, but they will make life a lot easier for you. Let’s take a look at just a few of these.

The command “no exec” is short, yet powerful. Occasionally you’ll have what is referred to as a “rogue EXEC” process tie up a line, and you end up having to continually clear lines, which disrupts your practice. If you have an access server, I highly recommend you configure this command on your lines, as shown here:

ACCESS_SERVER(con)#line 1 8

ACCESS_SERVER(con)#no exec

From your CCNA studies, you know that the command “no ip domain-lookup” prevents a Cisco router from sending a broadcast to find a DNS server anytime you enter something that is not an IOS command – and that includes mistyped commands, which happens to all of us sooner or later. Make sure to run that command in global configuration mode on all your practice routers.

There are two commands I like to configure on the console line on all my practice routers and switches. The first is “exec-timeout 0 0″, which prevents you from being kicked out of enable mode and back into user exec after a few minutes of inactivity. (This doesn’t sound like much, but you’ll get pretty tired of typing “enable” after a while.) The first zero refers to minutes, the second zero to seconds. Setting them both to zero disables the exec-timeout function.

The second command prevents the router from interrupting the command you’re typing with a console message. If you’ve ever been in the middle of typing a router command and suddenly you’re interrupted with a logging message, you know that can be pretty annoying. We don’t want the router to not display the message, but we do want the router to wait until we’re done entering data. The command to perform this is “logging synchronous”.

R1(config)#line console 0

R1(config-line)#exec-timeout 0 0

R1(config-line)#logging synchronous

You won’t see many of these commands on your exams, but after you configure them on your home lab devices, you’ll wonder how you did without them!

ISDN is a vital topic for today’s CCNA and CCNP candidates, especially for the ICND and Intro exams – you’ve got to know ISDN inside and out to pass those exams. Naturally you want to include it in your home lab. What many candidates don’t realize is that you can’t connect two Cisco routers directly via their Basic Rate Interface (BRI) interfaces you’ve got to have another device between them called an ISDN simulator.

An ISDN simulator is not one of those software programs pretending to be routers (“router simulators”) this is a piece of hardware that acts as the telephone company in your home lab. Older simulators come with preprogrammed phone numbers and SPIDs, where newer ones let you program the phone numbers you want to use. Either way, an ISDN simulator is great for your CCNA/CCNP home lab, because you can practice dial scenarios that actually work. And you get to troubleshoot the ones that don’t, which is also important to learn! )

You don’t need any special cables or connectors you just connect both of your routers’ BRI interfaces to the ISDN simulator with a straight-through cable and you’re ready to go.

In years past, this was a major problem for 640-801, 811, and 821 studies, because the simulators used to be so expensive. New ones can still be pricey ($600 and up), but with the sudden influx of used ISDN simulators on ebay and Cisco resellers, you can get a used one that will do the job for you.

Why are there suddenly so many ISDN simulators on the market? Cisco recently removed ISDN from the CCIE R&S exam, so a lot of CCIE rack resellers as well as private individuals are selling their simulators. There’s never been a better time to add ISDN to your home lab. If taken care of (kept out of extreme heat), they can last for quite a few years. The one I purchased for my IE home lab is still working well.

If you choose to purchase a new simulator, you can run a Google search to find vendors. I’ve made two purchases from www.vconsole.com over the last few years and both of those simulators have worked beautifully.

As I said earlier, there’s never been a better time to add ISDN to your home lab. Don’t just settle for trying to memorize theory – get your hands on the real deal, practice and fix your configurations, and you’ll be amazed at what you learn and how well you do on your CCNA and CCNP exams!