[nsp] WS-G5486 and WS-G5487

[sthaug at nethelp.no]

> It should work because both the LX and ZX GBICs have wide band receivers (eg 1200 - 1600 nm), 
> but you need to carefully check receive levels at installation time. The transit power
> of the 1000Base-ZX is strong (+5db) and if used on a short run you
> can saturate the 1000Base-LX receiver (-3db to -19db). 
> 
> Site A (1000Base-ZX)  <---- dark fiber ----> Site B (1000Base-LX)
> 
> Checks:
> a) The receive light level at Site B will need to be checked by a 1550nm light meter.
> b) The receive light levle at Site A will need to be checked by a 1310nm light meter.
> 
> I would recommend at least a 3db operational tolerance from either the maximum or minimum
> receive level for the GBIC. You can get troublesome links if the light level is too hot
> or too weak. 

Agreed. We had one fiber link which had been installed with ZX - LX
for various reasons. We saw occasional link downs at the ZX end, 
probably because the distance was right at the edge for the LX
power budget. We finally switched the LX with a ZX, and have had
no problems since then.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no