FirstServed Tech Blog - FirstServed and the Art of Server Tuning

When connecting to a Juniper router’s console port, do not use your everyday DB9-DB9 serial cable!
Although the Juniper M7 qualifies as a computer which runs BSD, it won’t be able to communicate using this type of cable.

So, what cable should you use?
Use a standard Cisco Roll-over cable, and use an RJ45 – DB9 converter at the router’s side (or both sides, depending on wether the cable had a build in DB9 connection at one of it’s sides).