Getting Started with Cisco ACI with ACI Simulator.

Recently, I have started my data center journey and was looking for something which can give me firsthand Cisco ACI experience. For ACI you need a lot of physical gear and the kind of lab I do it is totally impossible for me to practice something like this. So I looked for a virtual method to get started and I found Cisco ACI simulator. Cisco provides this free tool to give you the look and feel of Cisco ACI. And by look and feel, I literally mean just look and feel because there are only certain things that you can do with it. The reason for that is the switches that we have in the ACI simulator are the simulated ones and not the emulated ones as we have in GNS3 etc, with the simulation the biggest problem we have is the data path validation and that is precisely the limit that we have in ACI simulator, we cannot validate the data path. In case you want to avoid the pain of installation and later realize that you cannot achieve something you want to then I would suggest checking out the below datasheet on the Cisco website before you get started.

ACI Simulator Datasheet:

This document is excellently written to help the beginner and the most important part is the below table which talks about the main capabilities of the Cisco ACI simulator.

Fabric management●  Perform fabric discovery
●  Register leaf and spine switches
●  Show topology view
Creation of network constructs●  Build a tenant
●  Build a private Layer 3 network
●  Build a bridged domain
Specification of Cisco ACI policy parameters●  Create filters
●  Create contracts
Application deployment●  Create endpoint groups (EPGs)
●  Create an application network profile
●  Set provider contract
●  Set consumer contract
Virtualization: VMware integration●  Create VMM domain
●  Create VLAN pool
●  Create distributed virtual switch (DVS)
●  Add VMware ESXi hosts to DVS
●  Associate EPG with VMware vCenter domain
●  Associate virtual machine with endpoint port groups
Layer 4 through 7 services●  Deploy a service graph with an application network profile
Monitoring and troubleshooting●  View faults using GUI
●  View events using GUI
●  Set log retention policies
●  Capture API interchange for inspection
●  Show graphical view of managed objects
APIC Northbound API clients●  Python
●  REST with JSON and XML bindings
●  PowerShell

Now, after looking at these capabilities if you are still interested to install the simulator and getting started then below are the four-step procedure that you can use.

Step-1 : Download ACI Simulator Software from Cisco website.

For downloading the software you need to go to and download all parts of the software. The size of the Simulator is huge and the latest release 5.5 comes in six parts each 10 GB which makes the whole downloadable file size more than 60GB. Once the files are downloaded you need to use Linux “cat” command to combine all these six files. Older ACI releases have only four parts(40GB) in case you want to decrease the size of the download, make sure to read the release notes to ascertain your lab needs. Below is how we attach all files.

Ubuntu$ ls -l | grep aci
-rw-rw-r-- 1 shambhu shambhu 64039841792 Dec  5 17:54 acisim-5.2-1g.ova
-rw-rw-r-- 1 shambhu shambhu 10673306990 Dec  5 03:50 acisim-5.2-1g_part1.ova
-rw-rw-r-- 1 shambhu shambhu 10673306990 Dec  5 03:45 acisim-5.2-1g_part2.ova
-rw-rw-r-- 1 shambhu shambhu 10673306990 Dec  5 03:25 acisim-5.2-1g_part3.ova
-rw-rw-r-- 1 shambhu shambhu 10673306990 Dec  5 03:47 acisim-5.2-1g_part4.ova
-rw-rw-r-- 1 shambhu shambhu 10673306990 Dec  5 03:45 acisim-5.2-1g_part5.ova
-rw-rw-r-- 1 shambhu shambhu 10673306842 Dec  5 01:05 acisim-5.2-1g_part6.ova
Ubuntu$ cat acisim-5.2-1g* > acisim.ova

Step-2 : Choose a Host to Install ACI Simulator OVA file.

Once the step-1 process completes (may take 20 mins) you will get a singular ova(Open Virtualization Appliance) file. Now you can use any host that you have been using to open the OVA file. I have been using Oracle Virtual box since forever so I have installed it on my Oracle virtual machine. Here, you can find the specification from my VM. Please note the system settings. With this system setting, I have not seen any problem with the small topology (1 Spine , 2 Leaf , 1 Controller). If you are planning to install the large topology version then you may need a higher CPU because for me it seems to be very slow with large topology.

Step-3 Bringing Up the Simulator.

Simulator bring-up walks you through an interactive procedure where you will be asked a set of questions and on the basis of your response the ACI fabric will be setup. For this, we need to have a basic understanding of ACI and its components. Cisco has a very good document to help us walk through the procedure. You can find the document below(check ” Table-1: Setup for Active APIC”).

On the basis of the above document, I have setup my APIC simulator. Please find the whole APIC initialization process below, please take time to read through the questions that you need to answer while installing the Simulator. I have kept most of the settings as default as this is lab setup, but in the actual network, you need to customize settings more. One powerful thing about ACI is that it sets up the underlay, overlay, and management access by itself. That means we don’t even have to bother putting IP addresses or creating vlan for management access etc, the interactive initialization procedure asks us questions that help to setup the management, underlay and overlay networks. Once this is done, things are much easier for the application owners ( wasn’t that the goal for the application-centric network?)

Point to note, since this is simulator I have kept the password weak, in actual network of-course you will put passwords as per your company policy.

Step-4 : Login and Configure the Fabric.

Once the above setup is configured you can now login to the APIC console as well as GUI. For this, you need to remember two things.

1- The IP address you have assigned to the controller (in this case

2- Credentials that you have configured.

After putting the right details on your browser you will be presented with this welcome screen. Here you need to click on the “begin first time setup” button. This will take you to the first-time installation wizard where you can fill the required admin settings like NTP,DNS , Proxy etc but first of all, you need to register your Leaf and Spine devices.

For the Fabric membership, you need to click on the fabric membership and walk through the wizard. The whole process for a particular device like leaf or spine is divided into three steps.

Register >> Discover >>Activate

While the register is a manual process where you need to put device name and type (leaf or spine) the other two i.e. Discover and Activate process are automatically done by the controller.

Once this is setup we can go to fabric >> topology to see the complete fabric topology.


The setup is very simple and it definitely provides an excellent intro to the ACI world, but as I said there is a whole ACI world out there that is unexplored for me. The Cisco ACI release note correctly points out that you get GUI, CLI, and API with the simulator, all that you can do with the real ACI controller in terms of these three features can also be done with the simulator so seems like a very good tool for automation testings etc. I will see you with more blogs on this as and when I find out anything interesting in the simulator, till then keep learning and have a great time ahead.

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