Cisco IOS images for Dynamips

Yaser Rahmati | یاسر ر

GNS3 offers multiple ways to emulate IOS.

1. For older images, we use and maintain Dynamips;

   1. An emulator dedicated to emulate some Cisco hardware.

   2. Dynamips can run unmodified IOS images.

2. In the new GNS3 1.4, there is a way to run a second category of switches and routers.

   1. These are classified as Routing and Switching virtual machines (or R+Svms) for short.

Differences between IOS images and R+Svms

1. IOS images are usually run in Dynamips however R+Svms are housed in a virtual machine.

2. IOS images are lower in cpu and memory so you can fit more of them in one topology.

3. R+Svms are all vendor Routing and Switching images that are larger in size but can be imported into GNS3 for real world network emulation.

Idle-PC value

This settings will help Dynamips to consume less CPU. It’s specific to each different IOS image.

Recommended images

• We really recommend using c3640, c3660, c3725, c3745 and c7200 IOS images.

• They have proven to be the most stable in GNS3 provided you use the right amount of RAM and Idle-PC value.

Series	File name	Proposed idle-PC value
c3640
c3660	c3660-a3jk9s-mz.124-25d.bin	0x606071f8
c3725	c3725-adventerprisek9-mz.124-15.T14.bin	0x60c09aa0
c3745	c3745-adventerprisek9-mz.124-15.T14.bin	0x602701e4
c7200	c7200-adventerprisek9-mz.152-4.M7.bin