ISSU: Upgrade from FreeBSD 6.1-based Junos OS to FreeBSD 10.x-based Junos OS

You can upgrade from a FreeBSD 6.1-based Junos OS MX Series router to a FreeBSD 10.x-based Junos OS by performing unified in-service software upgrade (ISSU). A unified (ISSU) enables you to upgrade between two different Junos OS releases with minimal disruption on the control plane and with minimal disruption of traffic. Before performing a unified ISSU from a FreeBSD 6.1-based Junos OS to an upgraded FreeBSD 10.x-based Junos OS, the configuration must be validated on a remote host or on a routing engine. The remote host or the routing engine must be running a Junos OS with an upgraded FreeBSD.