[j-nsp] curious optic issue

[Saku Ytti]

Thanks to Steinar, Alexandre and 3rd person in other media the problem is
bit clearer now. 

I incorrectly stated I've seen this in other vendor too. Now when I double
checked my data, I realized the location where I thought it affected other
vendor I was looking at wrong end.
The other location was http://ytti.fi/ddm3.png 7600 XENPAK (other end is
JNPR and XFP from another vendor. Graph is coarser due to being older and
averaged out more)

Both the affected XENPAK and XFP were sold by same reseller. And I think
all of these resellers have bought from Gigalight. I'm not trying to name
and shame them, they are very common and resold by many companies, they
have good customer service and weird problems could affect any vendor. Plus
they are one of the most competitively priced option out there.
This particular vendor has probably some software defected optics out
there, it might be it only triggers after DDM counters have been polled X
times. Likely the root cause has been fixed long ago, but of course in
field affected optics still exists.

Like Steinar said, my best bet is to get optics replaced from this
particular reseller. And Alexandre's observation of it being temporal and
periodically reoccuring is interesting.

Obviously what ever the optic does, JNPR should not start to flap ISIS in
unrelated interface, if it's seeing optic misbehaving it should just power
down the optic. When this happened in CSCO, no other links suffered than
the affected.

> [....]
> > At least now I can go to DC, plug with my JNPR-crash-tool and crash
> > competitors routers with no traces in syslogs.
> 
> If my hypothesis is true, you have to wait for about eight months
> before crash happens :) 

I'm sorry I wasn't clear, that crash issue was completely different issue.
It crashes PFE immediately and always. JNPR has replicated it with these
optics in their lab in sunnyvale. And it's because some optics don't
respond to I2C polling in timely manner and JNPR does not handle this
gracefully.

-- 
  ++ytti