Junos OS Releases in the Routing Matrix
Junos OS Required
The TX Matrix Plus router and T1600 routers are delivered with the Junos OS preinstalled.
There are up to three copies of the software: one on a CompactFlash card (if installed) in the Routing Engine, one on the SSD1 in the Routing Engine (if installed), and one on a USB device that can be inserted into the slot in the Routing Engine faceplate.
When the TX Matrix Plus router boots, it first attempts to start the image on the USB device. If a USB device is not inserted into the Routing Engine or the attempt otherwise fails, the TX Matrix Plus router next tries the CompactFlash card (if installed), and finally SSD1 in the Routing Engine (if installed).
 | Note: SSD2 is not currently supported. |
If you are running a release prior to the Junos 9.6R2 release, you must upgrade the software release before connecting the fiber-optic array cables.
Running Different Junos OS Releases on the Routing Engines
We recommend that you run the same Junos OS Release on the master and backup Routing Engines. If you run the same Junos OS Release on all master and backup Routing Engines in the routing matrix, a change in mastership to any backup Routing Engine in the routing matrix does not cause a change in mastership in any other chassis in the routing matrix.
However, if you choose to run different Junos OS Releases on the Routing Engines, all Routing Engines on the same control plane must run the same Junos OS Release. All master Routing Engines in the TX Matrix Plus router and T1600 routers are on one control plane; all backup Routing Engines are on another control plane.
| Note: If you run different Junos OS Releases on the Routing Engines, a change in Routing Engine mastership might cause one or all T1600 routers to be logically disconnected from the TX Matrix Plus router. |
