Prior to Junos 10.0, for a standalone EX4200 switch to join an existing Virtual Chassis configuration, it had to be running the same version of software that was running on the Virtual Chassis master. Otherwise, the master kept the new switch in the inactive state. The automatic software update feature in Junos 10.0 gives the Virtual Chassis master switch the ability to automatically update the software on a new member switch so that it can join the Virtual Chassis configuration and be placed in an active state. The automatic software update feature is disabled by default. The user must enable the automatic software feature and provide a location of the software image through CLI. The command syntax is as follows: [edit virtual-chassis] user@switch# show auto-sw-update { package-name } The could be any of the following formats: Local directory: /pathname/Image-name—for a software package that is available from a local directory on any member Remote location: for software packages
http://www.ebrahma.com/2013/09/juniper-ex-series-automatic-software-upgrade-on-vc-member-switch/Labels: eBrahma