[j-nsp] curious optic issue

[sthaug at nethelp.no]

> I've seen at least twice now issues on XFP where temperature starts to draw
> weird saw-tooth, like this http://ytti.fi/ddm2.png

We've seen this too.

> Obviously I'm not running JNPR optic, but the two optics I've seen, have
> been from different vendors, who are not using same source. I think I've
> only seen it on 11.4R3 so far.

All the optics we've seen this problem with have been bought from a
specific local vendor. The vendor has agreed to replace the optics,
and as far as I know the problem has not reoccurred after replacing
the optics.

The problem was *not* Juniper specific. The problem showed up as a
module temperature reading that counted up to 127, wrapped around to
-128 and continued counting up. In other words pretty clearly an 8
bit counter. With counter values outside normal range, Juniper will
shutdown the port (sensible, in my optinion). Not all other vendors
will do so.

> Fix is to remove+reinsert optic, or reload router. I've not yet tried
> 'test xfp 1 power off|on', but I'm guessing it'll help too.
> 
> Anyone else seen this? My best guess is for some reason JNPR does something
> which causes the optic to do something which raises interrupt. And as it
> propagates to far-end, it should be something like maybe autonego? Maybe
> clock election? Which may cause both parties to police interrupts which
> might explain why ISIS on unrelated interfaces might timeout?  Highly
> speculative explanation, but it's all I've got.

I recommend you get those XFPs replaced.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no