New Year – new lab (Linux CentOS 7)

Anton Karneliuk. IT & Network Expert / Architect / Manager; Project Manager; Entrepreneur; 2x CCIE (RS/SP) #49412; MSc Telecommunications.

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  1. Just wonder. Instead of setting up all the routers images, bridge, software, vPC on Linux manually and from scratch, how about using network emulation software such as GNS3 and EVE-NG. They can simplify all these pumping things and let users focus just on router configuration.


    1. Hi Derek,

      for sure you can, but I don’t use any simulators. Here is why:

    2. First of all they use additional resources into PC. If you have them unlimited – no problem, but I don’t have them.
    3. Second point, my target is to see the whole picture in NFV world, not only router configuration, and be able to controll all components
    4. Third point, I don’t see any benefits besides simplification. With Ansible I get even more simplification.
    5. If like simulators, just used them.


  2. Hi Anton,
    I would like to thank you for all the work you are doing on this website.
    As a network engineer you are a source of inspiration for me !

    About the simulators (GNS3 for exemple), are you really sure that they are more resource-intensive than your lab (Nested VMs on VMware Workstation) ?



    1. Hi Marco,

      Thanks for the kind feedback. I haven’t used GNS3 for roughly 5 years, so I don’t know it development stage now. As I’m working a lot not only with network images themselves, but also heavily pushing automation and other stuff, for me it’s necessary to understand and be able to modify/control all components, what is quite easy in Linux, that’s why I’m using VM with it.
      Maybe GNS is good enogh in terms of resource’s usage and control it provides you, I don’t know. I just know that there is no magic and in GNS3 you will have to start VM Box with Nokia VSR what results in the same memory/CPU usage 🙂


  3. Hi Anton ,

    Very nice post , have similar things on mind.
    Can you share the hardware details of the node on which you did this lab .

  4. Hi,
    Is this installing Centos 7 as a guest OS on top of Windows OS?
    So you’re doing Windows as a host > Centos 7 as a guest (using vmware)
    Then you’re doing Centos 7 as a host > Nokia/Cisco as a guest (using KVM).
    Can you please confirm this is correct?
    If I want to use Centos 7 as my base operating system, and given that I only have one NIC. How do you recommend I should take care of creating virtual interfaces so build the topology?
    Thank you.

    1. Hi Karl,
      yes, you are right. I have Windows with CentOS 7 running as guest VM (using VMware Player or Oracle Virtual Box it doesn’t matter). Inside CentOS7 you can run any VM within KVM as explained here:
      If you want to run CentOS as you host without Windows, it’s fully OK. Basically, you don’t need any external connections for your VMs. So you need just to configure one port on your NIC to access the internet from your host OS and that’s it.


      1. Thanks Anton. I’d like you to help me with this small hiccup.

        I managed to install Centos and KVM on top of it. I also managed to launch SROS but the problem is there are limited number of commands (i.e. I can’t install cards, configure, or do a lot of things). The hostname isn’t changed based on the “configured” name in the XML file however I can Console to it. It feels like as if KVM isn’t executing all the parameters within the XML file. Is there a way to troubleshoot it?

        admin bof enable-vsd-config environment
        file password

        This is a snippet of my XML file:


        TIMOS:chassis=SR-c4 slot=A card=cfm-c4-xp mda/1=m5-1gb-sfp-b mda/3=m5-1gb-sfp-b address= static-route= license-file=ftp://user:password@



        <model type='virtio'/

  5. Hi Anton, Please correct me if I’m wrong. Centos VM only have one interface to internet right (NAT) and 2 custom interface vmnet3 and vmnet4. In step #6. Create appropriate network connections… how come got 3 interfaces ens33,34,35? I bit confuse how to map interfaces created over VM centos and this ens interfaces? Please clarify further. Thank you

  6. Hi Anton, appreciate if you can show how to create xml file for xrv. I only have iosxrvk9demo.qcow2 image…please assist and advise. Thank you

  7. Hi Anton… I create new Centos7 VM host(virtualbox)and installed KVM and create guest VM. I just maintain default network(virbr0/NAT) and to access externally the guest vm i create new bridge br0 and mapping to to interface enp0s3. (for your info, VM host able to access internet and can be accessed ssh in my lan via br0)..When i boot guest VM, it can get ip from my router dhcp and both host and guest vm can ping each other…….what puzzle me is that vm guest not able to ping router gw and not able to access internet. I have tried disable my host vm firewall but still the same. Please advise any. Thank you

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