[c-nsp] SX GBICs - too close?

[Jay Ford]

On Sun, 8 Aug 2004, Deepak Jain wrote:
> Can someone point me to a quick reference about distances that might be
> _too close_ for SX transceivers? (say 6" or 12") I have a few GBICs
> ports that take 5-10 minutes to "recognize" the other end, and if I do a
> "clear int" on one of the interfaces it goes away for between 5 minutes
> and an hour or two. It can only be bad hardware or a bad installer. :)
>
> Saturating the receiver is what I am hoping for because I'd rather blame
> the latter. heh

It shouldn't be possible to saturate the receiver with SX.  According to
http://www.cisco.com/en/US/products/hw/modules/ps872/products_data_sheet09186a008014cb5e.html
the allowable transmit range is -4 to -9.5 dBm & the receive window is 0 to
-17 dBm.

You actually have jumpers as short as 6-12"?  You're not supposed to use
jumpers shorter than 2 m (6.5').  I've gone as short as 1 m in bench testing
with no obvious trouble, but no shorter.

________________________________________________________________________
Jay Ford, Network Engineering Group, Information Technology Services
University of Iowa, Iowa City, IA 52242
email: jay-ford at uiowa.edu, phone: 319-335-5555, fax: 319-335-2951