[j-nsp] VC (2x EX4200) JunOS Upgrade without downtime ?

[Giovanni Bellac]

Hello

I am going on to do a JunOS upgrade from 10.0S10 to latest 10.4 due sflow issues 
in 10.0.

Here are the docs from Juniper:
http://www.juniper.net/techpubs/en_US/junos10.0/topics/task/installation/ex-series-software-installing-single-routing-engine-cli.html


It looks easy.

Each of our customer (layer2) rack-switches are connected with a trunk (lacp) to 
the VC.
So we can shutdown one EX4200 of the VC (2x EX4200) without downtime on paper  ?


I have read in the forums of Juniper, that you CAN NOT upgrade a VC without 
downtime, because the updated member will NOT join the VC.

Is that right ? Is a JunOS upgrade on a VC without downtime impossible ?

Best regards
Giovanni