Snippet: setting up nested virt for Juniper (GNS3)

October 20, 2024

vJunos-switch deployment guide - 5g, 4 cores

Juniper VMs nest the control plane inside a Linux VM emulating forwarding plane - for this reason, running virtualized Juniper devices in a VM can be problematic

I’d recommend not trying to do the above and using something dedicated

This is probably from an Ubuntu Server install:

See if nested virtualization is enabled

grep -cw vmx /proc/cpuinfo

Enable nested virtualization

echo "options kvm-intel nested=1" >> /etc/modprobe.d/kvm.conf modprobe -r kvm && modprobe kvm systemctl restart libvirtd

Interfaces on the switch should be named: fxp0 ge000 - ge0xx

-cpu host -smbios type=1,product=VM-VEX kvm options are REQUIRED:

without -cpu host or -cpu $something-with-vtx KVM won’t work
without smbios options the network interfaces won’t be assigned ge-0/0/x IDs

Once the vJunos switch is up:

root@:~ # cli
root> edit
Entering configuration mode

[edit]
root# set system root-authentication plain-text-password
New password:
Retype new password:

[edit]
root# delete chassis auto-image-upgrade

[edit]
root# commit
commit complete