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How to shut down laser on any optics
Howdy

I'm trying to shut down the laser from my optics from the junos cli in
order to ease troubleshooting. On MXes 240/480/960, mostly 17.4R2.

'set interface ge-<foo> disable' works *sometimes* on mpc2e with an
sfp, or on mpc2 with xfp, but fails (laser still emits) on some other
mpc2 with xfp too, and didn't find it working on mpc2e and mpc7e with
xfp and qsfp optics.

I know I can use 'test xfp <xfp index> laser off' from fpc shell, but
not only this doesn't seem to work on anything besides xfp, it also
requires shell access which I can't provide to everyone needing
port-level privileges.

All juniper genuine optics, with the same P/N between working and
non-working ones.

- would you consider the 'disable' not working as (I) expected a bug?
- is there some other magic cli command that would achieve what i'm after?

thanks in advance
pierre
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Re: How to shut down laser on any optics [ In reply to ]
> On Jun 24, 2020, at 10:50 AM, Pierre Emeriaud <petrus.lt@gmail.com> wrote:
>
> Howdy
>
> I'm trying to shut down the laser from my optics from the junos cli in
> order to ease troubleshooting. On MXes 240/480/960, mostly 17.4R2.
>
> 'set interface ge-<foo> disable' works *sometimes* on mpc2e with an
> sfp, or on mpc2 with xfp, but fails (laser still emits) on some other
> mpc2 with xfp too, and didn't find it working on mpc2e and mpc7e with
> xfp and qsfp optics.
>
> I know I can use 'test xfp <xfp index> laser off' from fpc shell, but
> not only this doesn't seem to work on anything besides xfp, it also
> requires shell access which I can't provide to everyone needing
> port-level privileges.
>
> All juniper genuine optics, with the same P/N between working and
> non-working ones.
>
> - would you consider the 'disable' not working as (I) expected a bug?
> - is there some other magic cli command that would achieve what i'm after?


Many of the optics don’t have a way to disable the laser except via custom commands over the i2c. Last I read the SFF MSA there wasn’t a good way to do this, and it wasn’t required.

- Jared
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Re: How to shut down laser on any optics [ In reply to ]
> On Jun 24, 2020, at 12:51 PM, Jared Mauch <jared@puck.nether.net> wrote:
>
>
>
>> On Jun 24, 2020, at 10:50 AM, Pierre Emeriaud <petrus.lt@gmail.com> wrote:
>>
>> Howdy
>>
>> I'm trying to shut down the laser from my optics from the junos cli in
>> order to ease troubleshooting. On MXes 240/480/960, mostly 17.4R2.
>>
>> 'set interface ge-<foo> disable' works *sometimes* on mpc2e with an
>> sfp, or on mpc2 with xfp, but fails (laser still emits) on some other
>> mpc2 with xfp too, and didn't find it working on mpc2e and mpc7e with
>> xfp and qsfp optics.
>>
>> I know I can use 'test xfp <xfp index> laser off' from fpc shell, but
>> not only this doesn't seem to work on anything besides xfp, it also
>> requires shell access which I can't provide to everyone needing
>> port-level privileges.
>>
>> All juniper genuine optics, with the same P/N between working and
>> non-working ones.
>>
>> - would you consider the 'disable' not working as (I) expected a bug?
>> - is there some other magic cli command that would achieve what i'm after?
>
>
> Many of the optics don’t have a way to disable the laser except via custom commands over the i2c. Last I read the SFF MSA there wasn’t a good way to do this, and it wasn’t required.

Correction (somewhat)

It’s not required for the hardware to implement this. There is a pin as well as bit you can set via i2c to (maybe) disable things:

- relevant part of MSA -
8.10

Enhanced Options [Address A0h, Byte 93]

The Enhanced Options are a one byte field with 8 single bit indicators which describe the optional digital diagnostic features implemented in the transceiver. Since transceivers will not necessarily implement all optional features described in this document, this field allows the host system to determine which functions are available over the two-wire serial bus. A '1' indicates that the particular function is implemented in the transceiver. Bits 3 and 6 of byte 110 (see Table 9-11) allow the user to control the Rate_Select and TX_Disable functions. If these functions are not implemented, the bits remain readable and writable, but the transceiver ignores them.
- snip -

They would either need to have the GPIO wired for this pin on the PCBs and/or implement disable sets this bit AND the optic would need to honor it.

- Jared
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Re: How to shut down laser on any optics [ In reply to ]
This would prove once again that vendor_endorsed_and_overcharged optics are just a useless scam.

This being said, we didn't experience this neither with Skylane nor Cubeoptics transceivers (currently on MPC7-MRATE / 18.4R[2-3]-[S*]). It «just works» as we expect (laser is switched off when the channel is disabled in the config). I would only expect to see another behaviour from some buggy/cheap/crappy network gears, whatever how lite the official specifications are, and therefore see this issue as a bug in a Juniper case.

Example of 2 different channels of a QSFP+ PLR4 (MTP):

Physical interface: xe-3/1/1:0 (disabled)
Lane 0
Laser bias current : 0.000 mA
Laser output power : 0.000 mW / -40.04 dBm
Tx laser disabled alarm : On
Physical interface: xe-3/1/1:1 (in use)
Lane 1
Laser bias current : 32.453 mA
Laser output power : 0.501 mW / -3.00 dBm
Tx laser disabled alarm : Off
[...]




> Le 24 juin 2020 à 18:59, Jared Mauch <jared@puck.nether.net> a écrit :
>
> They would either need to have the GPIO wired for this pin on the PCBs and/or implement disable sets this bit AND the optic would need to honor it.

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Re: How to shut down laser on any optics [ In reply to ]
Le mer. 24 juin 2020 à 18:59, Jared Mauch <jared@puck.nether.net> a écrit :
> >
> > Many of the optics don’t have a way to disable the laser except via custom commands over the i2c. Last I read the SFF MSA there wasn’t a good way to do this, and it wasn’t required.
>
> Correction (somewhat)
>
> It’s not required for the hardware to implement this. There is a pin as well as bit you can set via i2c to (maybe) disable things:
>
> - relevant part of MSA -
> 8.10
>
> Enhanced Options [Address A0h, Byte 93]
>
> The Enhanced Options are a one byte field with 8 single bit indicators which describe the optional digital diagnostic features implemented in the transceiver. Since transceivers will not necessarily implement all optional features described in this document, this field allows the host system to determine which functions are available over the two-wire serial bus. A '1' indicates that the particular function is implemented in the transceiver. Bits 3 and 6 of byte 110 (see Table 9-11) allow the user to control the Rate_Select and TX_Disable functions. If these functions are not implemented, the bits remain readable and writable, but the transceiver ignores them.
> - snip -
>
> They would either need to have the GPIO wired for this pin on the PCBs and/or implement disable sets this bit AND the optic would need to honor it.

Thanks Jared. So even with Juniper branded optics, same P/N, I guess
not all optics come from the same OEM, hence the "disable" stanza
working, or not.
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Re: How to shut down laser on any optics [ In reply to ]
Le mer. 24 juin 2020 à 21:29, Olivier Benghozi
<olivier.benghozi@wifirst.fr> a écrit :
>
> This being said, we didn't experience this neither with Skylane nor Cubeoptics transceivers (currently on MPC7-MRATE / 18.4R[2-3]-[S*]). It «just works» as we expect (laser is switched off when the channel is disabled in the config). I would only expect to see another behaviour from some buggy/cheap/crappy network gears, whatever how lite the official specifications are, and therefore see this issue as a bug in a Juniper case.

I'll open a case on this then, as this works for most of you, and
given the price of a current Juniper qsfp pluggable, one could expect
that it has all fancy optional features :)
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Re: How to shut down laser on any optics [ In reply to ]
On MPC7 can you please try test cmic fpc shell command?

On Wed, Jun 24, 2020 at 12:37 PM Pierre Emeriaud <petrus.lt@gmail.com>
wrote:

> Le mer. 24 juin 2020 à 21:29, Olivier Benghozi
> <olivier.benghozi@wifirst.fr> a écrit :
> >
> > This being said, we didn't experience this neither with Skylane nor
> Cubeoptics transceivers (currently on MPC7-MRATE / 18.4R[2-3]-[S*]). It
> «just works» as we expect (laser is switched off when the channel is
> disabled in the config). I would only expect to see another behaviour from
> some buggy/cheap/crappy network gears, whatever how lite the official
> specifications are, and therefore see this issue as a bug in a Juniper case.
>
> I'll open a case on this then, as this works for most of you, and
> given the price of a current Juniper qsfp pluggable, one could expect
> that it has all fancy optional features :)
> _______________________________________________
> juniper-nsp mailing list juniper-nsp@puck.nether.net
> https://puck.nether.net/mailman/listinfo/juniper-nsp
>
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Re: How to shut down laser on any optics [ In reply to ]
Le mer. 24 juin 2020 à 16:50, Pierre Emeriaud <petrus.lt@gmail.com> a écrit :
>
> Howdy
>
> I'm trying to shut down the laser from my optics from the junos cli in
> order to ease troubleshooting. On MXes 240/480/960, mostly 17.4R2.

> - would you consider the 'disable' not working as (I) expected a bug?

FYI, this is PR1376574, "Interface optic output power is not zero when
the port has been disabled.".
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