[c-nsp] Optical module transmit power

[Michael Robson]

We have a selection of ZR modules (XENPAK-10GB-ZR) in 6500s that we  
are using to drive some links at 10Gbps and I have recently noticed  
that all receive values (as reported via the sh int te x/y trans  
command) are lower than what Cisco specify as the minimum allowed  
values for those modules (i.e. the minimum quoted is -24dBm whereas we  
are seeing value reported as low as -28.8 dBm), and also a link that  
is receiving at -28.9dB and flapping. 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. 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, or is there some sort for  
decision/negotiation that determines the transmit value at connection;  
if the the latter, how can these modules be convinced to transmit at a  
higher power value?

Ta,

Michael
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