[179615] in North American Network Operators' Group
Re: DWDM and EDFA and DCM
daemon@ATHENA.MIT.EDU (Mikael Abrahamsson)
Thu Apr 23 00:01:39 2015
X-Original-To: nanog@nanog.org
Date: Thu, 23 Apr 2015 06:01:34 +0200 (CEST)
From: Mikael Abrahamsson <swmike@swm.pp.se>
To: Rodrigo Augusto <rodrigo@1telecom.com.br>
In-Reply-To: <D15D748E.378F6%rodrigo@1telecom.com.br>
Cc: nanog <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
On Wed, 22 Apr 2015, Rodrigo Augusto wrote:
> Buy 80km sfp+ dwdm modules? c21 and c51.
> On this scenario a donšt have a EDFA, only put these sfp+ and I have link
> on other side( 60km) but I have a -19dbm and other side I have -21dbm( ddm
> sfp+ output).. I think I have a better signal than this? because I use
> 80km sfp+ and my distance is 60km? can I have a chromatic dispersion? I
> think to use a EDFA, but išm not sure this? if I have a chromatic
> dispersion I have to use a DCM not a ADFA or a booster?
> Right?!
If you use 80km SFP+ then they should be able to handle the CD (chromatic
dispersion) of your 68km fiber stretch, and if you have a power problem,
then you can solve that by adding EDFA mid-span.
CD causes "noise" (OSNR) to the receiver, it doesn't cause your power
levels to be low. So if you want to solve your power problem, add EDFA
mid-span. If you want to be able to use 40km optics (they might be
cheaper), add DCM as well if the manufacturer rates them as not being able
to electronically compensate for dispersion more than 40km.
--
Mikael Abrahamsson email: swmike@swm.pp.se
