Reloading IOS config at CLI for Dynamips/Dynagen

From : Reloading config from Dynamips/Dynagen | David Sudjiman

I was having difficulty to save configuration after few labs I did with Dynamips. Saving config and reload the dynamips doesn’t work and I previously I have to copy and paste all the latest config I’ve had.

There is actually a trick to save config in Dynamips to text files (.cfg) and after starting the devices, you can import it back and run a command in your cisco device to load it.

Here is the sequence.

1. Once you’re done with your lab, copy the config using



copy run start

to copy it to


2. Then on your Dynagen console, you can save your config to a directory

export /all 'directory_name'

on your Dynagen console.
3. Next time you reload your dynamips, what you need to do is

import /all 'directory_name

4. Then on your Cisco devices run command configuration replace

nvram:startup-config force

5. Wait and you’re all set.”

I have made a copy for myself here so that I can find it in the future. Please check out David’s website.

About Greg Ferro

Greg Ferro is a Network Engineer/Architect, mostly focussed on Data Centre, Security Infrastructure, and recently Virtualization. He has over 20 years in IT, in wide range of employers working as a freelance consultant including Finance, Service Providers and Online Companies. He is CCIE#6920 and has a few ideas about the world, but not enough to really count.

He is a host on the Packet Pushers Podcast, blogger at and on Twitter @etherealmind and Google Plus

You can contact Greg via the site contact page.

  • Ivan Pepelnjak

    It’s even simpler. If you do “import /all” before you start the routers, they’ll automatically use the new startup configuration.

    BTW, I never use “autostart” in dynagen; I had problems with it in the Windows version (obviously some race condition). Additionally, I can only start a few select routers if I’m testing locally significant features in a larger lab.

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