[j-nsp] Understanding versioning of service and regular releases

[Richard A Steenbergen]

On Fri, Jun 03, 2011 at 11:58:00AM +0200, Tore Anderson wrote:
> On 2011-05-27, JUNOS 11.1S2 was released for the EX. So this release is
> a couple of weeks newer than JUNOS 11.1R2.3. However,
> <https://www.juniper.net/customers/csc/software/junos_software_versions.jsp>
> says 11.1R2.3 is the recommended version for the EX 4500 in VC
> configurations.

Let me throw out some warnings about 11.1S2 for EX real quick.

First off, when you upgrade a backup RE (we saw this on EX8200 but it 
might apply to VC's too) and are running some older code on the master 
(we saw this on several dfiff versions of 10.1, 10.2, and 10.3), there 
is a ~15% chance that when the backup RE comes online is will cause the 
router to completely stop forwarding traffic. This isn't a case of the 
backup stealing control of the pfe, and it doesn't leave anything in the 
logs, it just silently disrupts the master RE so it can't reach 
anything, and stays that way until you restart the router or switch over 
to the 11.1 RE. We've seen this happen several times now on several 
different routers, no GRES or anything like that, and there is no PR 
yet.

Also, they've done something to royally hose the sync process between 
master and backup RE on this code. When running 11.1S2 on the backup, 
and any of a dozen different versions of 10.1, 10.2, or 10.3 (haven't 
tested 10.4, doesn't seem to happen when both REs are running 11.1S2), a 
commit sync will always fail. This wouldn't be so bad, except that on EX 
(at least on EX8200) you CAN'T disable commit sync, even if you don't 
specify it it always does it. This means that you will never be able to 
commit with the backup RE online, and the only workaround seems to be to 
reboot the backup RE before you commit on the master so that it sees it 
offline and successfully ignores it. Again no PR on this yet.

No experience with it on 3200/4200/4500/VCs yet, but based on our 
experience w/EX8200 so far this code should come with a warning label, 
may be hazardous to your health. :)

-- 
Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)