[c-nsp] 10G SFP+ ASR9001 LOS

[Florian Lohoff]

On Wed, Apr 05, 2017 at 12:45:56AM +0100, Tom Hill wrote:
> On 04/04/17 12:48, Florian Lohoff wrote:
> > Are there more debugging possibilities to find the cause for
> > the laser shutdown? I still think the SFP is faulty but
> > that means the whole lot is broken in some respect.
> 
> I assume you've tried the basics?
> 
>  1. Cross-connect cable cleaned end-to-end

Swapped
 
>  2. Swap for new optic (yes, you have)
> 
>  3. Tried a different port?

Did so

> I'm curious; when the LOS happens, what are the Tx/Rx SnR values?

Around -5dBm well within the warning low at -15dBm - So yes - plenty
of optical power budget left.

> You've stated that the optic is shutdown at present, so I'd assume that
> -40dBm Tx is only as a result of that, not a symptom. Can you elaborate
> on the symptoms in terms of Tx/Rx figures, and/or if there are any
> excessive errors/discards before the LOS?

The line works for sometimes weeks without a flaw. Sometimes it fails
twice a day. I am Monitoring rx/tx optical power levels doesnt show any
fluctuation (got it in grafana at 1Min intervals). When the LOS happens
the only thing you will observer is that the TX power goes to -40dBm
which causes the remote end to signal an Remote Fault Indication (RFI)

> Have you spoken to the upstream to ask if their monitoring has a poor Rx
> value?

I have asked for details and the power levels for the opposite direction
are also well within the transceiver bounds.

IMHO there is no reason at all for the SFP to shut down the laser
if it receives an optical signal until instructed to do so by the
ASR. The fault must be on our side as WE can fix it with shut/no shut
which basically resets the SFP.

Logs only show interface going Operational Down and a Remote fault
received.

Flo
-- 
Florian Lohoff                                                 f at zz.de
             UTF-8 Test: The 🐈 ran after a 🐁, but the 🐁 ran away
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