Category Archives: Arista

Connecting NXOS VIRL instance to Arista vEoS

In this blog, I will cover the steps that I did to connect Cisco NXOS VIRL switch instance to Arista vEoS switch instance. We can connect any Cisco switch simulated in VIRL, I just picked the NXOS switch type. CML/VIRL supports majority of Cisco switches as VM as well as few external switches from Juniper, Vyatta. External virtual or physical switches can be connected to Cisco switches running inside VIRL using VM Networking magic. I just think it is cool to connect Virtual devices, try out real-time network configurations and see how the device responds.


  • Install CML/VIRL using the procedure here.
  • Install vEoS using the procedure here.
  • I used VMPlayer to run VIRL and vEoS. Connecting across Virtualbox and VMWare player is little painful.

Following is the network I created:

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Ansible for Arista EoS

This is a continuation of my previous blog on Arista Eapi. Ansible provides a recipe driven approach to manage servers/switches, I have covered Ansible in some of my previous blogs. In this blog, I will cover the following:

  • Ansible modules for Arista device
  • Ansible galaxy eos role for Arista device

There are 2 approaches to use Ansible with Arista device. Following picture from Arista illustrates this point:


  • The first approach is called remote approach from Ansible perspective. Here the ansible python script is transferred to Arista device using ssh and the python script is executed on the Arista device which connects locally to the device using Pyeapi which in turn talks through eapi.
  • The second approach is called local approach from Ansible perspective. Here the Ansible python script is run locally in the client machine which in turn talks to Pyeapi library which in turn talks to the remote device using eapi.
  • Typically, network devices dont allow running scripts directly on the device. In that case, only second option would be possible. In Arista’s case, there are no restrictions like this and both the approaches can be used for Ansible based automation.

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Arista Eapi and pyeapi

I had covered basics of Arista EoS and vEoS in my previous blog. Arista’s Eapi gives programmatic approach to manage Arista devices. Arista’s Pyeapi Python ¬†library is built on top of Eapi. In this blog, I will cover the following:

  • Eapi
  • Pyeapi library

I have used Arista vEoS for trying out all examples below without needing a physical Arista device. That shows the power of virtual device.

There is lot of similarity between Arista’s Eapi and Cisco’s NXAPI. I covered NXAPI in 1 of my earlier blogs. Arista’s Eapi is equivalent to Cisco’s NXAPI, Arista’s Pyapi library is equivalent to Cisco’s Pycsco library. Arista’s Eapi provides http/https access to the Arista router/switch through which we can send standard CLI commands and the output is received in JSON/XML formatted output. There is no need to do screen scraping with this approach, this makes it devops friendly. Arista’ Pyeapi is available as a github project.


To enable Eapi in Arista device, do “management api http-commands” in config prompt. Following is the output in my Arista vEoS switch:

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Arista EoS and vEoS

I had heard some good things about Arista EoS(Extensible Operating System). I have never used Arista switches before. I did some reading on Arista EoS and I also tried their VEoS which is their Virtual machine offering for running Arista switch as VM. In this blog, I will share some of my experiences.

EoS Overview:

I found this block diagram in Arista White paper:


Following are the things that I liked:

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