Emulating Juniper Devices – Various options



I have got a lot of requests for writing up a blog post on various Methods of emulating Juniper devices for practice.

Note : For 2/3 methods to work, you need to have official Junos software (vmx-vcp and vmx-vfp)

Method 1 – Gns3

Most popular and Familiar Method – Install via gns3

After installing Gns3, download the

Vmx-vfp Appliance – https://docs.gns3.com/appliances/juniper-vmx-vfp.html

Vmx-vcp Appliance – https://docs.gns3.com/appliances/juniper-vmx-vcp.html

Documentation is straight forward, all you need to do is double click on the appliance and upload the image when requested, as easy as it can get.


Method2 – Vagrant

Use Juniper uploaded Images via vagrant.

Most of Juniper Vqfx / JNCIE-DC practice came up from a vagrant, You don’t need to have any official images or access to Juniper software downloads. The downside is that it only supports VQFX and generic SRX, but for most of the Routing protocol and MPLS learning this should be good.




Again, following Github link, will auto setup the topology without you worrying about much details to vagrant.

https://github.com/Juniper/vqfx10k-vagrant -> Go into a specific folder and say vagrant up, that should take care of installing and bringing up the boxes


Method3- My personal favorite as of now – Advanced Method.

Via Docker

A good blog post on how to do it

Deploy Juniper vMX via Docker Compose

but am following the method from VRNET lab package from Github, it took a while to figure out the specific way to set up this after reading instructions but its really worth it.


You need to have some understanding of Docker and need to read up how to set up connectivity between containers, but once you get to know it most of it can be scripted and automated.

There are some other paid and free emulated tools but most of it I wanted to reduce the scope which is supported by a global group of people via Git and it will have a future scope of development when compared to Tools which are closed source.






VPLS IN VMX !! – Vmx is Awesome



I wanted to setup VPLS in VMX, Back in 2012-2013 during my studies for Jncie-sp track, we never had this tool for simulation, though oilve was around helping with complete layer-3. Thankfully i had partner-labs then and also our own lab setup to play around with VPLS. But again nothing as satisfying as playing it analyzing it on your system.

Tools Used :

Xshell – Terminal Emulator

Vmware- Workstation 12



Lets see the topology


Core comprises of

BGP/RSVP/MPLS/OSPF – Lets quickly check everything in place,  I will discuss the connectivity as well


Lets see the IOU / Vmware connectivity



Lets quickly check, Vpls configuration / Bgp configuration, Am keeping it simple by showing only on one device.



The most important thing, not that instance wont run if you dont have vt, it still finds it way via a LSI interface, but the general flow described in JMV is also via VT interface



Lets see if we have arp flooding , kindly remember the arp addresses, that will be verified on end-nodes




Final Ping verification From end-nodes



Rakesh M


What is Lt Interface – How are Logical systems Built in Juniper Mx without a cable ? – JNCIE-SP

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Most of the times I get queries about my preparation for Juniper SP track. While the questions are based on two categories, one what study materials have i used, secondly how i practiced. While the first question is something which I will cover in another blog post, this is mainly based on second Query on how did i practice.

I worked for Juniper Networks – So Its sort of Obvious that i had access to devices, mostly the high end ones like T640 and T320 , T320 with XE-interface Loop was my all time favorite though.

Secondly, again my work experience helped with a huge migration from Juniper 120 boxes to Cisco ASR series and had a lot of fun and struggle then.

But for JNCIE exam, all that matters would be how good you are actually at technology. It will really not matter if you are using a VMX or Real device say Mx/Ex/M/T/SRX box, a simple olive can also do, service provider Layer-3 preparation is beautiful 🙂

Coming to the point, I had access to device which has no Mic Cards, No Physical interfaces (literally not coming up) so i cannot use a loop-cable to do what so ever in regular fashion.

It was just lying around there, waiting for its turn to be Turned off. I was to do some internal training’s and saw this guy perfectly suitable for 14 odd routers by using Logical Tunnel interface. Yes, if you have an MX , even if its physically not possible to loop around, you can build your virtual systems and play around using LT.


First things first, I will show you the procedure for building Two Logical Routers, but procedure remains same for almost any number of routers




This is interface that you should be looking for

show inter terse | match lt
lt-1/0/0 up up



This is how you build the tunnel interfaces

Test#show interfaces lt-1/0/0
unit 1 {
encapsulation frame-relay;
peer-unit 2; ( logical unit number of the opposite-end connecting interface)
dlci 12;
family inet {;
unit 2 {
encapsulation frame-relay;
peer-unit 1;( logical unit number of the opposite-end connecting interface)
dlci 12;
family inet {;


Finally you integrate them into logical-systems

test#show logical-systems
r1 {
interfaces {
lt-1/0/0 {
unit 1;

r2 {
interfaces {
lt-1/0/0 {
unit 2;

run ping logical-system r2
PING ( 56 data bytes
64 bytes from icmp_seq=0 ttl=64 time=0/650ms











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