You want to install a different release of JUNOS software on a J-series router.
First, retrieve the JUNOS install package, junos-jseries, from the Juniper Networks web site (http://www.juniper.net/support) and copy it to a local server. You can install the software directly from the server:
aviva@RouterA> request system software add validate unlink reboot server1 :junos-jseries- 7.4R1.7-export-cf256.gz
You can also copy the software to the router and then install that copy:
aviva@RouterA> file copy server1: junos-jseries- 7.4R1.7-export-cf256.gz /cf/var/tmp aviva@server1's password: junos-jseries-7.4R1.7-export-cf256.gz 100% 64MB 774.5KB/s 01:24 aviva@RouterA> request system software add validate unlink reboot /cf/var/tmp/junos-jseries-7.4R1.7-export-cf256.gz
To upgrade to a newer software release, first download the J-series install package, junos-jseries, from the Juniper Networks web site (http://www.juniper.net/support) and copy it to a local server and then to the router. When moving the package to the router, a good place to put it is /cf/var/tmp.
The request system software command includes a few options. The validate option checks that the new software is compatible with your current router configuration file. When you are updating to a different release of the JUNOS software, the validation check is performed automatically. The unlink option removes the software package from the router as soon as possible to make more room on the hard disk for the installation to complete. The final option reboots the router after the validation and the installation complete and if the upgrade is successful. When the reboot is complete, you see the login prompt.
Use the request system software add command to install the new software. During the installation, the filesystem on the router's flash disk is rebuilt and all components of the JUNOS software are completely reinstalled. Configuration information from the previous software installation is retained, but the contents of logfiles might be erased. This is why you take a snapshot of the software using the request system snapshot command before you load a new version of the software (see Recipe 1.19).
Juniper Networks web site (http://www.juniper.net/support); Recipes 1.19, 1.20, and
Router Configuration and File Management
Basic Router Security and Access Control
Routing Policy and Firewall Filters