[j-nsp] EX4200: VC "incremental upgrade" ?

[Alexandre Snarskii]

On Mon, Oct 25, 2010 at 03:31:47PM +0200, Philipp Geschke wrote:
> On Mon, 25 Oct 2010 17:10:46 +0400, Alexandre Snarskii <snar at snar.spb.ru>
> wrote:
> > Hi!
> > 
> > Silly question: is it possible to perform "incremental upgrade"
> > on ex-series virtual-chassis ? I.e., upgrade some switches
> > (using 'request system software add member NN'), switchover
> > master to 'upgraded' part, then upgrade remaining switches ? 
> 
> no, that is currently not possible.
> You can always take single switches out of the stack and upgrade them
> outside of the stack, however, a hitless upgrade is not really possible.

Looks like it is possible. In progress of building new virtual-chassises
I found that one of VC's periodically flapped (pfem coredumps with 
corresponding interface flaps) right after commits.
Investigation shown that it was because of version mismatch 
on one of stack members: 

snar at vsw02# run show version | match "Base OS boot|fpc"
fpc0:
--------------------------------------------------------------------------
JUNOS Base OS boot [10.3R2.11]
fpc1:
--------------------------------------------------------------------------
JUNOS Base OS boot [10.3R2.11]
fpc2:
--------------------------------------------------------------------------
JUNOS Base OS boot [10.3R2.11]
fpc3:
--------------------------------------------------------------------------
JUNOS Base OS boot [10.3R2.11]
fpc4:
--------------------------------------------------------------------------
JUNOS Base OS boot [10.3R1.9]

and after upgrading JunOS on fpc4 to match others I see no more
errors. However, the fact that 10.3R1 switch was able to join 10.3R2
virtual-chassis leads me to interesting conclusion - looks like
incremental upgrade within the same major version, like 10.3R1 to 
10.3R2 to 10.3R3 is possible, while upgrade from 10.3 to 10.4 is not. 
And, of course, there must be no configuration changes during upgrade.

PS: or it is well-known bug to be fixed in some next release ? 

-- 
In theory, there is no difference between theory and practice. 
But, in practice, there is.