[c-nsp] Catalyst SX GBIC's and SMF

[Tim Winders]

I believe this is only with Cisco's "full size" GBICs and not with the SFP 
GBICS.

--

Tim Winders
Associate Dean of Information Technology
South Plains College
Levelland, TX 79336

On Fri, 7 Jan 2005, Lindahl, Carl wrote:

> Per Cisco
>
> http://www.cisco.com/en/US/products/hw/switches/ps708/products_data_shee
> t09186a008014cb5e.html
>
> You can run LX GBICs on MM Fiber w/ a specific "mode conditoning" patch
> cord.
>
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net]On Behalf Of Justin M.
> Streiner
> Sent: Friday, January 07, 2005 12:34 PM
> To: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] Catalyst SX GBIC's and SMF
>
>
> 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
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