This post is a set of my notes on Dynagen setup. Dynagen is a text-only frontend to the kewl Dynamips software emulation for Cisco router for use when studying for exams or whenever you need to emulate a router. You can also use this article to set your idle-pc value and reduce CPU usage from the Dynamips server. You can get Dynagen and the embedded Dynamips from Dynagen SourceForge site and there is a nice Windows installer you can download directly.

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IOS Images. Resource Utilization. Configuring your Telnet Client. Network Files. Running Simple Lab 1. Working with the Management Console. Calculating Idle-PC values. Simple Lab 2. Frame Relay Lab. Communicating with Real Networks. Ethernet Switch Lab. Memory Usage Optimizations. Packet Capture. But this works on Windows?

What gives? How do I submit a quality post on the forum or the bug tracking system thereby increasing the likelihood that someone will be able to help me out? Dynamips is a Cisco router emulator written by Christophe Fillot. It emulates , , , , , , and hardware platforms, and runs standard IOS images. This kind of emulator would be useful to:. It would allow people to become more familiar with Cisco devices, Cisco being the world leader in networking technologies ;.

Dynagen simplifies building and working with virtual networks:. Dynagen is written in Python, and is therefore compatible with any platform for which there is a Python interpreter which is to say, many. Other Python applications could be written that use this API for programmatically provisioning virtual networks, or to provide other front-ends. If somehow you have stumbled upon this tutorial without first finding the Dynamips or Dynagen web sites, here they are along with some other important links:.

This library is used by Dynagen for reading its configuration files. Dynagen runs on any platform that supports Python, which is to say nearly any platform. I have also put together a Windows installer package that includes Dynamips and provides a compiled version of Dynagen, eliminating the need to install Python. First, install libpcap, or winpcap depending on your platform on the machine on which you intend to run Dynamips.

This is used to provide bridging router interfaces to physical network cards. Windows users will need to install Winpcap 4. Then, Windows users should install the Windows installer package. Dynamips runs real Cisco , , , , , , and IOS images. From the Dynamips FAQ:. Can you provide a Cisco IOS image for a to me? No, I am not allowed to distribute any IOS image.

You will have to find one by yourself, this should not be a problem if you are a Cisco customer. You can actually drop the images anywhere you want, but the sample labs are configured to look here. Cisco IOS images are compressed. These compressed images will work just fine with Dynamips, however the boot process is slowed significantly by this decompression process just like on real routers.

You will receive a warning from unzip, which you can safely ignore. See the Memory Usage Optimizations section for configuration options that can signficanly reduce memory utilization. More on this later. Dynagen includes a console command that allows you to connect to the virtual router consoles directly from the CLI.

But you must first configure the dynagen. Uncomment the line appropriate for your system, or craft your own to use your favorite telnet client.

See the comments in the ini file for instructions. This file uses a simple INI file-like syntax. Open up the simple1. Simple lab. Any line prefaced with a is a comment, and is ignored. The first section specifies the host that is running Dynamips. In this case, we intend to run Dynamips on the same machine as Dynagen, so we specify localhost. The next section is indented, and double bracketed. This means that what follows is configuration that applies to the Dynamips server specified in the section above in this case, localhost.

All whitespace is actually ignored, so the indentation is just for looks. The double-bracket is what really means that this section is nested under the [localhost] section. This [[]] section defines all the defaults that will be applied to any router instance we create. Note that you can specify defaults, and later override them in specific router instance definitions.

The image keyword specifies the location on the system running Dynamips in this example our local machine of the image we want to use by default for all router instances. Here we are pointing to a It has nothing to do with the hostname that you assign in IOS to the router although it will probably be less confusing if you just keep them the same. Now we create a 2 nd router, creatively name R2. None of the keywords are. No need to specify an adapter here, it is taken care of.

Although we have to create the R2 router, we do not need to specify any adapters here. In order to run this virtual lab, first start up the Dynamips server on your local machine.

Running this starts up the server listening on port by default in a window like this:. For example:. On Windows, open the simple1. To see all the devices in this virtual lab, use the list command:.

They are both currently running on the local host. Telnet to these ports to connect to the virtual router instances. Or, if you configured the dynagen. However the Windows telnet command included with the OS does not seem to allow this. If anyone can come up with a work-around for this please let me know. But Dynamips lets you know which router you are connecting to as its first line of output inside the telnet window, so you can identify it that way.

From the Management Console, use the help command to see a list of valid commands:. To get help on a particular command, either type help command or command?.

I have not yet found a suitable Python Readline library for Windows to provide this functionality. Help shows the syntax as:. To shut down a single router, type use stop routername :. And sure enough, the router is now stopped:. The IOS reload command is not suppored by dynamips in virtual routers. So you can use the Dynagen reload command. It performs a stop, followed by a start. The suspend and resume commands have a similar syntax as stop and start, but they temporarily pause the specified routers:.

The exit command stops and deletes all devices from the network, and exits dynagen. If you exit the Management Console, your simulation will no longer be running. This is because Dynamips does not know when the virtual router is idle and when it is performing useful work.

Here is how the process is performed. First, open a lab and make sure only one router instance is running stop any others in the lab if need be :. Then, telnet to the running router instance. Otherwise, do not press anything:. Wait for all the interfaces to initialize, then wait a bit to ensure that the router is no longer booting and is idle.

Your session should look something like this:. You will see a message that statistics are being gathered, and about 10 seconds later you should see a list of potential idlepc values:. Values that will most likely provide better results are marked with an asterisk. Select one of the values to try from the menu and press Enter.

You should notice your host the one running the dynamips process CPU utilization drop dramatically.


I love dynamips/dynagen

IOS Images. Resource Utilization. Configuring your Telnet Client. Network Files. Running Simple Lab 1. Working with the Management Console. Calculating Idle-PC values.


CCNA – Dynagen / Dynamips Setup

Practice for certification success with the Skillset library of over , practice test questions. We analyze your responses and can determine when you are ready to sit for the test. In a world where things are becoming more and more virtualized, it is no surprise that virtualization has also come to the world of skills development. For networking, that virtualization has come in the form of a program called Dynamips. Dynamips is a platform which allows you to virtually start up, connect, configure, and run a network — all inside of your own computer. What would normally have cost thousands of dollars in equipment to procure can now be done free of charge.



In addressing the router enables wireless networking connection, really amazing what Technology has changed these days. I like meeting new things. This is why i have come to this blog, I find it very interesting. This is like costa rica investment opportunities really interesting too. Post a Comment. What is Dynamips?

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An Introduction to Dynamips

The source code is available on GitHub if you are interested in taking a peek at the code. Join the community or volunteer to check code or add code recommendations. With over , community members, we can all learn from each other. There are, however, other options available that you can use. Dynamips is a Cisco router emulator written by Christophe Fillot. It emulates , , , , and hardware platforms, and runs standard IOS images.

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