How To - Step By Step Installation of JunOS on GNS3 [Part 4]

Posted by Ahsan Tasneem | 11:08 PM | , , , , , , , , , , , , , , , , , , | 0 comments »


To check if everything work, let’s configure 2 Olives:

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

root#set interfaces em0 unit 0 family inet address
commit complete
Configure the other device using the same commands but with another IP address (e.g. and ping.

Exiting configuration mode
root> ping
PING ( 56 data bytes

64 bytes from icmp_seq=0 ttl=64 time=9.771 ms
64 bytes from icmp_seq=1 ttl=64 time=0.614 ms
64 bytes from icmp_seq=2 ttl=64 time=0.693 ms
64 bytes from icmp_seq=3 ttl=64 time=0.630 ms
Additionally, configure OSPF (or any other multicast based protocol) to test if your routers can talk to each other using multicast packets. Again, type those commands on both routers:
root# set protocols ospf area 0 interface em0

root# commit
commit complete

root# exit
Exiting configuration mode
Then monitor the traffic from one of the router, you should see some multicast traffic (from/to
root> monitor traffic interface em0

02:30:30.973748 Out IP > OSPFv2, Hello, length 48
02:30:31.007675  In IP > OSPFv2, Hello, length 48
Is everything working? yes? then you are successfully running JunOS! Happy networking

What is working

Here is a list of what has been tested and works. You can extend this list by posting comments on what is working or not for you and I’ll update the list:

 OSPF (fxp0)                                  OK
 OSPF (em0)                                  OK

A few words about the patch

By default using JunOS with a non-patched Qemu, multicast based protocols didn’t worked. As I have very little driver coding experience (and time to learn), I patched Qemu to allow multicast frames to be received by JunOS, instead of being filtered at the driver level multicast frames are filtered by JunOS. The only problem I see could be on the performance side, as JunOS receives every multicast frames, even those not destined to it. However, I think this is not an issue for a simulated lab environments and it worked just fine so far.
If you feel you can do something cleaner, please don’t hesitate, you can still read one of the Intel manuals concerning the e1000 to have an overview of how complicated driver programming can be ;)


If you are IT guy (hope you are if you want to play with JunOS), you should be able to run JunOS on your PC without too many issues. I wrote this howto to be as complete as possible, showing how to compile and patch Qemu on 3 different operating systems, installing FreeBSD and JunOS. I encourage everyone to contribute to it by providing fixes, comments or any other help.

Related Articles
How To - Step By Step Installation of JunOS on GNS3 [Part 1] 
How To - Step By Step Installation of JunOS on GNS3 [Part 2]
How To - Step By Step Installation of JunOS on GNS3 [Part 3]


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