Cisco cert lab prep: Sim vs Em vs Real

Alas, there are so few mind readers in the world these days... ;-) So, let me add some context and some why's/wherefore's to this series on build a CCNA and CCNP lab using real gear. (Way back last year, when I did the original series on CCNA/CCNP prep labs, I took the time to give this same context, but it bears some repeating.)

First, the broad view: you can use Simulators, and/or Emulators, and/or real gear, in order to build hands-on skills for the exams. If you buy a Sim, the Sim should have documentation, so I don't bother blogging about it. If you get the one Emulator (Dynamips/GNS3 family), there's already tons of easily-accessible information online, so I haven't spent time on it here in the blog. For buying real used gear, there seems to be not as much online info and recommendations, so that's where I spent some time on this topic last year, and will again this year. But, it's worth a day to ramble about the options...

Simulators, by my definition at least, are software products that outwardly act like real gear, but inwardly can do whatever they want. Being software products, the features beyond that base description vary wildly. For example, I have seen some products over the years that follow a pre-defined set of steps, and the user cannot deviate from those steps. If you follow the steps, the output looks like real gear. Others allow greater freedom, so that you can type any (supported) command on the simulated devices, with behavior that mimics the real gear. Some Simulators support the creation of your own topology of different models of routers, switches, and maybe other devices as well, while others use a static set of pre-defined topologies. (I'm sure there are other comparison points; I'm just listing a few as examples.)

Emulators, defined at least in the context of the public Cisco space, means software that both outwardly and inwardly acts like the networking devices. Specifically, that means freeware Dynamips/Dynagen (http://www.dynagen.org/) and it's graphical front-end GNS3 (http://www.gns3.net/). (If you start at the Dynagen web site, you'll see several good links to learn more.) Short version - get the free code, and then it runs multiple instances of router IOS on your PC. You can connect the instances to each other via LAN or serial, and to the outside world. It's real IOS, so it's very realistic. It's free. It didn't support Cisco switch IOS last I looked, but it supports basic emulated LAN switches. And it's both cool and useful.

And, there's real gear. More to come on that.

If you plan on being in the Cisco space for a while, you may end up with all three. Between the three, there is no cut/dried answer to which option you should use. I do think there are several points to consider, which I'll list several here in the remainder of this blog post. So... considerations?

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