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What controls SFP TX Power

Posted: Mon Aug 01, 2016 12:34 am
by candh
I was wondering if anyone knows what determines the TX Power set on Mikrotik's SFP+ modules?  I've got a link where it's suddenly dropped and as a result the other side can't see me any more.  Testing out the link with loops that's defiantly the issue.  Is there anyway to manual over-ride it?  

Also, I can't work out what SFP rate select does?  Any wiser person know that?

Re: What controls SFP TX Power

Posted: Mon Aug 01, 2016 6:28 am
by cutedrummerboy
i am also interested.

Re: What controls SFP TX Power

Posted: Mon Aug 01, 2016 2:25 pm
by haik01
As far as I know it is set in the hardware.

If you experience problem because the link is too small, then you can "overpower" the receive part on the other side. Then you can use an optical attenuator.

Also, the "further" km is written on the SFP, the stronger (more powerful) the laser should be.

So if you use a 50 km SFP for a 1 meter pigtail between Mikrotik and a switch, that might cause a problem on the switch side.

Re: What controls SFP TX Power

Posted: Mon Aug 01, 2016 8:39 pm
by candh
Thanks haik01, that's the conclusion i'm coming to so far.  The reason I ask is that i've got a module where it's suddenly changed dramatically when nothing else in the loop has.  I know with some you can override this.

Re: What controls SFP TX Power

Posted: Tue Aug 02, 2016 6:28 am
by cutedrummerboy
As far as I know it is set in the hardware.

If you experience problem because the link is too small, then you can "overpower" the receive part on the other side. Then you can use an optical attenuator.

Also, the "further" km is written on the SFP, the stronger (more powerful) the laser should be.

So if you use a 50 km SFP for a 1 meter pigtail between Mikrotik and a switch, that might cause a problem on the switch side.
not stronger power because when i measured power of an sfp i always saw -5 to -5.5 dbm. after some research i found that it is the receiver sensitivity which give you the power to achieve longer distance link.