Introduction to Spanning-Tree

Hello Laz,
I want to comment on this suggestion. I encountered the same problem as Ajmal. Indeed some limitations of Packet Tracer. It’s indeed dissapointing when lessons use examples which you can’t replay in Packet Tracer. But to suggest that VIRL (now CML) or GNS is an solid alternative is not the complete truth. Both have their shortcomings as well. CML because there is only an IOS-VL2 switch image available with Gb interfaces (no fa ethernet, which makes it bit more difficult to follow labs where fa interfaces are being used like in this Networklessons course:

Rebuilding labs in CML on the basis of examples in networklessons like said above is not always a good thing to do because the results are different.

In CML there is an unmanaged switch as well but you can’t use it for the SPT labs.

GNS3 has its shortcomings as well and as far as I know there is still no good alternative for a managed switch. Only when you use a 3600 series router and turn it into a switch: ttps:// (Update: It is possible to use a IOSVLs2 switch but this image must be downloaded from the cisco website which is not free (more then 200 euro for a subcription cml).

Actually the best solution is indeed to built your own ccna lab with real hardware but that is not an option for some people with a small purse.

So far I have no experience with connecting a real switch to GNS3 of CML but there is a ton of information on internet howto.

In your answer I miss some nuance and advising GNS3 as an possible alternative for spanning tree labs is something I do not agree with. There are some obstacles.

Hello Michel

I appreciate your response to these issues, and I do agree that each possible solution to labbing does have its pros and cons. Packet Tracer is indeed limited in its capabilities for STP and for some other technologies, and you do need to seek other solutions for that.

Although GNS3 and CML do have their drawbacks, they are better than Packet Tracer in several areas. GNS3 can be difficult to deploy sometimes, and CML is not free. But I believe that you can get them to function sufficiently in order to study the content for CCNA and even CCNP level certifications.

As you mention, the only surefire way of making STP and other technologies work flawlessly is to use real equipment. But again, that’s not free.

Ultimately, using these tools (free or not) is an investment in time and money. Obviously, you will try to do it as efficiently as possible, however, some time/money must be spent. Using a combination of these, although not always ideal, should be more than enough to fulfil the requirements of certification.

Other than the emulators mentioned there are other as well that you can research such as EVE-NG for example. Take a look at this NetworkLessons note that contains some more ideas about home labbing.

I hope this has been helpful!


Hello Laz,

Thank you for your answer and the link. Of the four I have never used EVE-NG. I think I will give this a try. GNS3 is working now, I downgraded to an older version 2.2 .46 and I managed to add all the IOS images including IOSVL2 and IOSV, ASA firewall and many many other. For the rest I am using Packet Tracer, CML and I invested the last weeks in some real equipment mostly buyed from Ebay.

4 X Cisco Catalyst 2960 24 / 48 T
4 X CIsco Catalyst 3750
1 Cisco WS-C3650- 48 Ports POE switch
1 APC KVM console server 32 ports
1 ASA firepower (firewall) next generation
2 1921 cisco router
3 1841 cisco router
1 Cisco 876-K9 router
1 Cisco IP Phone

Hope that this is sufficient for the CCNA labs and CCNP in the future.

Best regards,

Hello Michael

Your whole lab setup, with your real equipment as well as your GNS3, Packet Tracer, CML, and now your experimentation with EVE-NG are more than enough to cover all of the topics you need to become proficient for CCNA and CCNP level certifications. Many people have been successful in their certifications with much less than what you have, so you are in a very good position. Labbing is one of the most important parts of learning for certifications, so I belive you’re covered for virtually all topics.

I hope this has been helpful!


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