[c-nsp] Optical module transmit power

[Dale W. Carder]

On Apr 30, 2009, at 9:37 AM, Michael Robson wrote:
> We have a selection of ZR modules (XENPAK-10GB-ZR)

> For these modules, none of them are transmitting at anything like  
> their maximum of +4.0dBm (Cisco's figures for the maximum transmit  
> power), they are in fact transmitting between +1.9dBm and +2.3dBm.

This is to be expected.  Vendors just publish a tolerable
range somewhere in which the optics will operate.

> What determines what they will transmit at i.e. is it simply that  
> better manufactured ones achieve a transmit value closer to the  
> +4.0dBm power level

Maybe it's luck.

Anyway, how long are your fiber spans?  If they are really
long, and you're living on the edge now, you may end up in
a sticky situation as these optics degrade over time.

If they are not extremely long, you may have some horrible
jumpers or splices that are eating some dB.  Do you have
an OTDR?

Dale

p.s. My fiance did her postgraduate work at Manchester.
      Quite a nice place!