[j-nsp] Power issues on 10Gig link

[Tim Rayner]

Yes, by all means clean the fibre patches at both ends... both the patch leads, and the fibre at the back of the FOBOT.. And clean any intermediate patching.... And an OTDR test can identify anything along the path that is causing higher than expected loss....

However, it may be that the easiest solution is to step up to 10GBase-ZR optics - which tend to have a power budget of around 23 dB, rather than the 10GBase-ER which typically have a power budget of ~ 15 dB.

Tim.

Tim Rayner
Optical Engineer, AARNet Pty Ltd
street address: Building 9, Banks Street, YARRALUMLA  ACT  2600
postal address:  GPO Box 1559, CANBERRA   ACT   2601
t. +61 2 6222 3575     f. +61 2 6222 3535     e. Tim.Rayner at aarnet.edu.au
w. www.aarnet.edu.au
Network Faults (24x7): 1300 APL NOC (1300 275 662) or noc at aarnet.edu.au

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________________________________________
From: juniper-nsp [juniper-nsp-bounces at puck.nether.net] on behalf of Jared Mauch [jared at puck.nether.net]
Sent: Friday, 24 January 2014 12:36 AM
To: Ali Sumsam
Cc: <juniper-nsp at puck.nether.net>
Subject: Re: [j-nsp] Power issues on 10Gig link

On Jan 23, 2014, at 8:14 AM, Ali Sumsam <ali+junipernsp at eintellego.net> wrote:

> Hi All,
>
> I am using a SFP-10GBase-ER for my Cisco3750X for a 10gig link going to a
> Juniper MX5-T router (10GE XFP)
>
>
> I am receiving following logs on my Cisco3750X.
>
> %SFF8472-5-THRESHOLD_VIOLATION: Te1/1/2: Rx power low alarm; Operating
> value: -21.3 dBm, Threshold value: -20.0 dBm.
>
> No logs on Juniper.
>
> Does this mean I have to increase the power on the interface?
> Or is there anything else I need to look at?
>
> Following are the readings from my Juniper router.
>
> Laser rx power high alarm threshold       :  1.2589 mW / 1.00 dBm
>    Laser rx power low alarm threshold        :  0.0158 mW / -18.01 dBm
>    Laser rx power high warning threshold     :  1.0000 mW / 0.00 dBm
>    Laser rx power low warning threshold      :  0.0199 mW / -17.01 dBm
>

You need to take a look at your span length and OTDR numbers.

Was there recently a bend in the cable that caused this attenuation?

Do the light levels improve when cleaned?

If you replace the optic does the situation improve?

Is the launch power the same in both directions, but just low on the RX side facing the Cisco?

Finding the answers to these questions should resolve your alarms.

- Jared
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