On Fri, 7 Jan 2005, Mikael Abrahamsson wrote:
On Fri, 7 Jan 2005, Robert Walton wrote:
I've currently got two catalyst 4000's connected via a single mode
fibre using SX GBIC's in an ad-hoc network configuration - at present
I've seen no service degredation and the link from box-to-box is about
40m. According to the cisco spec's these gbics should only be used with
multi-mode fibre, does anyone know over what distance you would start
hitting problems when using SMF with SX GBIC's?
It is not really a distance problem, it's a getting-light-into-the-hole
problem. You're using a laser designed to put light into a 50 or 62.5
mikrometer diameter hole, into a 10 mikrometer hole. Basically the surface
area of this hole is much less than designed. On the other hand, the light
that actually gets in there will be less degraded over distance.
I would definately not recommend using SX gbics over SM fiber for
production purposes. Better to purchase some LX GBICs off of ebay if your
budget is tight.
Indeed. As a general rule, using SX GBICs with singlemode fiber is not
recommended, nor is the reverse - LX/LH/ZX GBICs ober multimode. You can
run into all kinds of problems related to modal or chromatic dispersion in
those cases. This could show up as link flaps, interface errors, or some
other fun problem :-) The reverse would be more dangerous because the
potential exists to fry the receiver optics in your LX/LH/ZX GBICs.
jms
11 messages in net.nether.puck.cisco-nsp[c-nsp] Catalyst SX GBIC's and SMF 
