Networking gear can be irritating some days.  Case in point, the Catalyst 5500 at work, with its WS-5410 line card and WS-G5484 GBICs.

Everything on Cisco’s site says that these devices work together (and they do), and that the G5484 GBICs are 62.5/50 micron adapters designed to talk to multi-mode fibre.

Yet the only cable that works (ie, that makes the CatOS say the port is connected) is a 9 micron core single-mode fibre.

It. Should. Not. Work.

But. It. Does.

Does. Not. Compute.

I even tried the cabling and GBICs in another switch.  Same result.

Argh.