Replicating DC Environment in GNS3 for Pre-Change Testing

[Rayman99]

Hello everyone, I am looking to use GNS3 to replicate part of our production DC environment to perform pre-change testing. Our environment consists of:

2 x Cisco ASR routers
4 x Nexus 9K switches
2 x Cisco ASA firewalls
4 x Catalyst 9500 switches

My main questions are

1. Has any of you this before and if so were you able to use the same OS images that run on the physical devices in GNS3?
2. What limitations to keep in mind, if any, from these platforms (especially Nexus 9K and Catalyst 9500) ?
3. If what I'm trying to accomplish isn't possible in GNS3, can you recommend an alternative solution for labbing changes in a non-production environment before taking the changes live?

Thank you in advance for any insight or advice from those that have attempted this before.

[MHM Cisco World]

That impossible for gns3 or eve-ng 

Try use cisco CML

MHM

[Rayman99]

Why not gns3 and why is CML better?

[MHM Cisco World]

CPU and RAM need for gns3 VM is huge for your requirment 
use CML which is Cloud base

MHM

[Rayman99]

Doesn't CML also require significant use of CPU and RAM regardless where you're deploying it?

[MHM Cisco World]

https://blogs.cisco.com/learning/how-to-run-cisco-modeling-labs-in-the-cloud

[Torbjørn]

1. I prep changes simulating them in EVE-ng/CML all the time. Note that you can't use the same image as the physical device but you can use a virtual equivalent. Eg. C9500 == C9000v, ASA == ASAv...
2. Refer to the documentation for limitations. Note that not all limitations are listed here, you will have to experiment some: https://developer.cisco.com/docs/modeling-labs/nx-os-9000/#nx-os-9000 
3. CML is the best way to go considering that it is supported, but EVE-ng has some nice additional functionality. GNS3 will also work if you load the correct images.

[Rayman99]

Is the CML Enterprise license required for my use case or can we get away with CML personal +? Can a topology in CML be accessed by other users to test changes or is this something only CML Enterprise supports?

[Torbjørn]

As I have interpreted the CML licensing(not an expert): CML personal is a _personal_ license and deployment which cannot be directly shared with other users, while an enterprise deployment is intended for multiple users. There are some licensing limitations regarding exporting the images for use in EVE/GNS3 etc. as well, so if you intend to use this in production you will be best served by deploying an enterprise CML instance.

[Ramblin Tech]

The Offer Description for CML-Personal states that it is for non-commercial use by a single, named person, but allows it to be used by a commercial entity employee for evaluation purposes. CML-P only allows a single user ID to be configured, while CML-Ent allows multiple user IDs. So, no, CMP-P cannot legally be accessed by users other than the person named at the time of purchase of the subscription.