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

[Stefan Fouant]

> -----Original Message-----
> From: juniper-nsp-bounces at puck.nether.net [mailto:juniper-nsp-
> bounces at puck.nether.net] On Behalf Of Giovanni Bellac
> Sent: Sunday, March 20, 2011 4:33 PM
> To: juniper-nsp at puck.nether.net
> Subject: [j-nsp] VC (2x EX4200) JunOS Upgrade without downtime ?
> 
> 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/installatio
> n/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
> ?

In my experience, you can do this and maintain availability of the entire
VC, however individual member switches may themselves go down for a period
of time while the upgrade takes place.

In your environment, because you have 2x EX4200s, you should be able to do
this without any downtime whatsoever as long as you are doing VC-LAG between
the customer switches and the VC.  In this case, while the Master is being
upgraded and switches mastership priority to the Backup, traffic will flow
via the remaining path in the VC-LAG through the Backup (now assuming the
role of the Master).

Perform the upgrade on the Master and it will ensure that all member
switches are upgraded, so you won't have to worry about individual member
switches not joining the VC due to incompatible code, etc.

Good luck!

Stefan Fouant, CISSP, JNCIEx2
www.shortestpathfirst.net
GPG Key ID: 0xB4C956EC