Category Archives: Juniper

Achievement Unlocked: JNCIA Certification

After having a few Cisco certifications under my belt, I felt it would be wise to start diversifying my skills. When I received a free exam voucher it pushed me to go for it. As far as exam content goes, 65 multiple choice questions with a few multiple choice/multiple answer questions was it. No simulations or interactive questions. I passed with minimal studying. If you do not have your JNCIA certification and you are thinking of going for it, I would recommend taking a shot at it. As long as you have some basic networking skills, can do some binary math, and have used JunOS, you will probably pass. One downside is that it is only valid for 2 years, instead of 3 like Cisco.


So much time wasted for such a stupid problem

Let me preface this by saying that remotely rebooting a router/firewall always has associated risks; however, this one may never cross your mind as I’ve found out the hard way.  Apparently, Juniper does not want you to have a Cisco terminal server (aka reverse telnet) connected to their devices’ console ports.

I had been planning on upgrading from JUNOS 11.4R1.6 to the latest 12.1 release because I’ve noticed some weird/undocumented issues with its DHCP server implementation (to make a long story short, DHCP acknowledgments were taking excessively long to process and send out in response to a request).  After the old “request system software add … reboot” command I sat and patiently waited for the box to come back to life; unfortunately, it never did.

Almost by accident, I stumbled upon Juniper KB17145 entitled “SRX reboot can have problems when console cable is connected to Cisco terminal server.”  My favorite sentence is: “misconfiguration on the Cisco port can cause SRX not to boot properly”

This is how Juniper wants you to configure the Cisco serial port:

line aux 0
  session-timeout 7200
  exec-timeout 0 0
  no exec
  transport preferred none
  transport input all
  stopbits 1

So I applied their recommended configuration, rebooted the SRX, and magically, it booted properly!