Gns3 support diffrent network devics to simulate. Cisco routers work in gns3 with dynampics, on the other hand if you want to run juniper router on gns3 you need qemu or oracle virtual box. In this post we will learn how to run juniper router in gns3 environment.
We need following software :

1. Gns3 - Download Gns3
2. Oracle Virtual Box - Download Virtual box
3. Juniper Router image -Download via torrent

Steps:
1.Download and install Gns3 if you don't have from the above link.
2 Download the Juniper router image from the above given link.
after the juniper image is downloaded keep it in a seprate folder.
3. now run Gns3 and go to :
Edit > Preference > Qemu > JunOS

 4. Now put some name in the identifier name and browse the downloaded juniper image in the field binary image as example see the following screenshot.


Save the JunOS image and click apply then ok.

now you will see that juniper router is active in the router-list.
Drag and drop the juniper router and clisk start and open the console of your juniper router after the router boot completes it will ask for login type root and press enter you will get the access of router.
 Enjoy !!!

Virtual box method will be posted soon