GNS3 with breakout switch connected to four 3750s.

JackaceJackace Member Posts: 335
I know that we will probably see an update to the CCIE curriculum soon, but with the current curriculum what can't be done with GNS3 and a breakout switch connected to four 3750s? I ask because at the moment I have access to these switches, but I only have one 2800 router. All my other test equipment at work is service provider equipment and things are just different enough in that equipment that I'm afraid it would cause issues.


  • ZartanasaurusZartanasaurus Member Posts: 2,008 ■■■■■■■■■□
    I didn't run into one thing I couldn't do in GNS3 that was in the INE workbooks. That said, there are bugs in GNS3 that have to be learned and worked around. The major one is multicast. All routers, except for the 7200, contain a bug in the code that causes the queue to fill when multicast traffic is present. Your pings stop working, adjacencies drop, etc. Best bet is to stick with 7200s in your lab, expect when working with NTP. NTP causes 7200s to lock up for some reason. I tried several different IOS versions to the same result. Of course, multicast is way more prevalent and important than NTP, so living with NTP bugs is better than living with multicast bugs. Also, if your startup-config contains subinterfaces, the main interface starts admin down, even when specifcally told to no shut in the startup-config. Didn't have that problem with the 3725s, but it's a minor issue IMO.

    I imagine all GNS3 labs going forward will be 7200-based when the new version hits since that's the only one that supports IOS 15. Either that or everyone will move to IOU.
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  • JackaceJackace Member Posts: 335
    Thank you very much for your insight.

    I like the idea of IOU, but from what I have heard it is more limited than GNS3 and has just as many bugs.
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