Dynamips basic configuration

Now that my server is up running with it’s wireless card just fine, it’s time to begin configuring dynamips/dynagen. The first thing you’ll need is a few IOS images. Of course I cannot provide this for you, you’ll have to get it yourself.

You can put your IOS images wherever you want, but I’ve put mine in the following folder: /data/dynamips/IOS_Images/7200

If you remember back from your CCNA studies, you’ll remember that IOS images are in fact COMPRESSED. You can leave it like this but it’s easier to just uncompress it now. You’ll have plenty of hard drive space and this will allow dynamips to actually use less horsepower later as it won’t have to uncompress on the fly.

Make sure unzip is installed. If not on Ubuntu just type:

sudo aptitude install unzip

Once that’s complete just go to the folder in which you have you IOS image and unzip it. This is my example:

[email protected]:/data/dynamips/IOS_Images/7200$ ls

$ unzip c7200-a3jk9s-mz.124-25b.bin
Archive:  c7200-a3jk9s-mz.124-25b.bin
warning [c7200-a3jk9s-mz.124-25b.bin]:28712 extra bytes at beginning or within zipfile
(attempting to process anyway)
inflating: C7200-A3.BIN

$ ls
C7200-A3.BIN  c7200-a3jk9s-mz.124-25b.bin

$ mv C7200-A3.BIN c7200-a3jk9s-mz.124-25b.UNCOMPRESSED.bin
$ rm c7200-a3jk9s-mz.124-25b.bin

As you can see it’ll spit out a warning but just ignore that.

You now need to configure your telnet client. This can be done like so:

$ sudo vi /etc/dynagen.ini

Just uncomment and/or change the relevant paths so it’s correctly configured for your platform.

Now it’s time to create the topology itself. I’ve created mine in /data/dynamips/Topology/simple.net (You’ll need to change the paths to match yours)

autostart = false
workingdir = /data/dynamips/working

      image = /data/dynamips/IOS_Images/7200/c7200-a3jk9s-mz.124-25b.UNCOMPRESSED.bin
      npe = npe-400
      ram = 160

      model = 7200
      s1/0 = R2 s1/0

[[router R2]]
      model = 7200
      # No need to specify an adapter here, it is taken care of
      # by the interface specification under Router R1

Now start dynamips like so:

dynamips –H 7200 &

Now load your topology:

dynagen /path/to/sample.net

You’ve now got dynamips/dynagen running. In future blogs I’ll get a lot more advanced. We also need to set the idle pc values which really is one of the most imporant things you’ll need to do

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