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Click here to view the Class-on-Demand on using Dynamips for CCIE Lab Preparation

Click here to view the CCIE Routing & Switching Dynamips Hardware Specification

Using Dynamips for CCIE Lab Preparation on Mac OS X

Since the beginning of networking related certification one of the recurring problems that have faced candidates is getting access to hardware to familiarize themselves with how network operating systems work. Traditionally candidates have been limited to hunting for great deals on old or refurbished equipment to buy, renting equipment time from rack rental vendors, using severely limited router simulator programs, or testing configurations on live customer networks and praying that the help desk's phone doesn't ring. Today candidates now have an additional option for creating a Cisco IOS testbed, an emulation program known as "Dynamips".

Started in August of 2005 by Christophe Fillot, Dynamips is a Linux and Windows based application that is used to emulate the hardware of the Cisco 7200 and 3600 series routing platforms. Unlike traditional router "simulators" Dynamips allows you to boot real Cisco IOS software images and build complex network topologies to test the functionality of IOS on your desktop PC. As of November 2006 Dynamips currently supports Ethernet, Serial, ATM, and POS interfaces for the 7200 series routers and Ethernet, Serial, and Etherswitch modules for the 3600 series routers. Best of all Dynamips is open-source and free to download!

To run Dynamips first you must install libpcap or winpcap depending on your platform. Windows users will need to install winpcap 4.0 or later which is currently in beta.

Next download the appropriate Linux or Windows executables for Dynamips. To do this I would recommended to download the Dynagen installer package, a front end written by Greg Anuzelli which uses an INI-like configuration file to provision the Dynamips emulator.

Next you'll need a Cisco IOS software image for a 7206, 3620, 3640, or 3660 router depending on which platform you will be emulating. IOS can be downloaded from http://www.cisco.com for users with a valid service contract. Once you have downloaded the appropriate IOS image it is recommended that you extract the image to save time in the Dynamips booting process. This can be accomplished with programs such as gunzip for Linux or WinRAR for Windows.

Next you need to build a Dynagen .net file to provision the Dynamips emulator, or you can download prebuilt ones to emulate the Internetwork Expert Routing & Switching and Service Provider topologies from here:

Click here to download the Internetwork Expert Topologies for Dynagen

Note that these files may need minor modification to specify your working directories and the names and locations of your Cisco IOS images. Also included in the Internetwork Expert topologies for Dynagen is a router instance that is designated as a Terminal Server (Access Server). This instance can be used like a Cisco 2511 series router to reverse telnet to the console ports of the virtual Dynamips router instances, similar to how the Terminal Server is used in the CCIE Lab Exam.

To use the Terminal Server instance first create a Loopback interface on your PC with the IP address 169.254.0.1/16. For Windows clients see http://support.microsoft.com/kb/839013 for instructions how to add a Loopback interface in Windows. Once the Loopback is created reboot your PC and then run the Dynamips shortcut "Network Device List" located on the desktop. This output will show you the hardware address for the Loopback which will look something like {4065B11C-2A6C-4FD2-8204-A12A9A8328A4}. Next edit the .net file for the appropriate Internetwork Expert topology, and under the [[Router TermServ]] entry edit the line E0/0 = NIO_gen_eth:\Device\NPF_{4065B11C-2A6C-4FD2-8204-A12A9A8328A4} to insert the hardware address of your Loopback. If successful you should be able to ping the IP address of the Terminal Server (169.254.0.2) from your local PC when the Dynamips instance for it is booted.

Next boot the Dynamips hypervisor. For Windows users this will be the "Dynamips Server" shortcut on your desktop that was created by the Dynagen installer package. Next run the appropriate .net file for Dynagen, and "start" your devices from the Dynagen command line. Once booted the Dynamips router processes can be telneted to with any terminal emulation software such as SecureCRT, PuTTY, HyperTerminal, or command line telnet.

Note that as the number of device you boot in Dynamips increases as do the processor, memory, and disk space requirements of your desktop. Currently I am able to boot all the devices in the Internetwork Expert Topology .net files in Windows with an AMD 64 X2 Dual Core 4400+ processor with 2Gb of RAM and about 2Gb of disk space in the devices' working directory.

As the project matures more functionality is sure to be added. For more information on the project visit the following sites:

Dynamips: http://www.ipflow.utc.fr/index.php/Cisco_7200_Simulator
Dynagen: http://dyna-gen.sourceforge.net/
Hacki's Forum: http://7200emu.hacki.at/

Internetwork Expert now offers CCIE Routing & Switching Dynamips Lab Workbooks Vol. 1 and 2. Click for more information about our Dynamips Workbooks.

Hi Brian,

any idea about installing GNS on ubuntu or Linux

which is the better one to run complete lab as i am facing savere issues running complete lab on my Vista ...

Hi Rajiv,

I have recently started with my prep and I have installed GNS3 and dynamips on Ubuntu. It did take me some time to make every thing work but at the end it works great or at least so far. What I found out is Ubuntu is vey popular and there are tons of resources on line from where we can get help.

Let me know if you have a specific question and I will try to help or at least point in right direction.

Regards,

Ather

hello Sir,

any idea how to set IdlePC value in dynamips as well as in GNS3.

after readying the manula of GNS3 .. I have done this...after getting value with * use to go "edit" select working IOS and again say edit with current value will come which I replace with the one I got from IDLEPC program and when after saving I start the IOS again but CPU usage was stilll 50 - 100 percent. I have done this several times but in vain. I reading they are saying keep on doing this untill and unless you will get the cpu usage less then 5% but believe there will be shortcut for that..

with dynamips I tried ti fix idle pc value but after giving command every time I am facing this massage "R1 already has an idlepc value applied.
to recalculate idlepc for this device, remove the idlepc value from your lab or from your dynabenidledb.ini" ................any help if I may get???

Best Regards.....Ahmed.

simply edit the .net file with notepad (after backing it up) and add # before each line that has idlepc at it's begining

then save your file and run int in dynamips - now all routers have no idlepc value and you can try and change it till you get the correct one

once you have a "good" idlepc value then add it in a line on the .net file, like this -

idlepc = 0x6094b6bc

enjoy ...

Good Day,

I have tried but in vain... is there is any video or screenshots type documentation from where I may get the iidea.

moreover in GNS3 I noticed that I can set the IdlePc value for the routers but also I noticed that after setting the values when I start the router to work CPU goes upto 100% again untill and unless I turn off the routers. also is there any way we can save the IDLEPC value for ever in GNS3 same like dynamips????

Best Regards

Ahmed Ashfaque:

moreover in GNS3 I noticed that I can set the IdlePc value for the routers but also I noticed that after setting the values when I start the router to work CPU goes upto 100% again untill and unless I turn off the routers. also is there any way we can save the IDLEPC value for ever in GNS3 same like dynamips????

http://7200emu.hacki.at/viewtopic.php?p=18903#18903

Good Day,

Sir, I have done it...I notice that after starting GNS3 right click on the desired router and then ask for the calculation and after getting the value with * you should just say o.k and while putting o.k you should notice that CPU utilization should come to 0 means you get the right value other wise you have to repeat the process untill and unless you get the right value with CPU process.

Thanks for all the advices and efforts.

Best Regards. Ahmed.