[j-nsp] MX upgrade to 15.1R4.6: loopback filters drop all traffic

[Saku Ytti]

On 18 September 2016 at 10:18, Chuck Anderson <cra at wpi.edu> wrote:

Hey,

> Has anyone upgraded from 14.2 to 15.1 and seen this issue?  Right
> after the upgrade, all loopback filters started dropping all traffic
> causing OSPF & BGP failures, inability to ping or SSH into fxp0, etc.,
> despite being configured to allow the appropriate management & control
> plane traffic which was working perfectly fine in 14.2.
> Deactivating/reactivating the filters "fixed" the issue, as did a full
> box reboot.  Of course JTAC can't reproduce it.  64-bit Junos,
> RE-1800X4's.

I've seen similar in ISSU years ago. Once after ISSU lo0 filter
dropped LDP, another time after ISSU one particular customer filter
was dropping things it should not have, forcing reprogramming helped
in both case.

And yeah, probably is going to be challenging to reproduce. I wonder
if implementations even try to verify correctness, do they ask HW
about state they just changed/added/removed, to confirm what code
asked actually did occur.

Not picking on Juniper here, I've seen various HW programming issues
in other vendors too.
-- 
  ++ytti