Best Cisco IOS for GNS3

The best IOS version to emulate everything on GNS3 is IOS 7200. With this you can do everything. Frame-Relay Switch to BGP, ISIS etc, just everything.

For switching you have to use IOU. You can't rely on Swicth Module with 3640.

I'm using Cisco IOS Software, 7200 Software (C7200-ADVENTERPRISEK9-M), Version 15.2(4)S3, RELEASE SOFTWARE (fc1) for Frame-Relay Switch Lab.

S2(config)#do show run | inc switch

frame-relay switching