[179612] in North American Network Operators' Group
Re: DWDM and EDFA and DCM
daemon@ATHENA.MIT.EDU (Rodrigo 1telecom)
Wed Apr 22 18:42:32 2015
X-Original-To: nanog@nanog.org
From: Rodrigo 1telecom <rodrigo@1telecom.com.br>
In-Reply-To: <CA+78=sFOmBFUEzPTp=wgJhTtZDGEh0hfnonZrPnxReaaPMBQYw@mail.gmail.com>
Date: Wed, 22 Apr 2015 19:43:22 -0300
To: Evelio Vila <evelio@thousandeyes.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
Nothing is wrong with the fiber... Attenuation is good... Gbics specs says -=
23db as a limit of your sensibility ...i have tried to put bidi sfp+ 80km on=
this fiber and have -25dbi on other side( not connect) this module have -20=
dbi sensibility ...
This scenario have a 4 channels... And i use 2 10gb channels... C21 and c22 o=
n side A and c51 and c52 on side B....
Enviado via iPhone =EF=A3=BF
Grupo Connectoway
> Em 22/04/2015, =C3=A0s 19:01, Evelio Vila <evelio@thousandeyes.com> escrev=
eu:
>=20
> I think the OP is asking about whether it should account for chromatic dis=
persion or not. Intramodal dispersion may very well be a limit on your link e=
ven the power budget (as presented before) is fine. As Mikael said, I would=
stick to the specs from the manufacturer for that specific module, or rent a=
n OTDR and make the measurements.
>=20
> --
> Evelio
>=20
>> On Wed, Apr 22, 2015 at 1:51 PM, Baldur Norddahl <baldur.norddahl@gmail.c=
om> wrote:
>> First: buy a power meter. They are really cheap and the only way to know
>> for sure how much signal you got. It will also tell you how much launch
>> power you have. The fiberstore modules are listed as 0 to +5 dBm launch
>> power - if you got lucky it might be +5 and if you got a lower end module=
>> it might be close to 0. Obviously this makes a huge difference for how mu=
ch
>> power you get on the other end. Also it is said that the laser will lose
>> power over time.
>>=20
>> Second you need to think in terms of power budget, not distance. So you g=
ot
>> 68 km and the module is rated for 80 km - but not all fiber is not born
>> equal. A power meter allows you to measure the true link loss.
>>=20
>> Third you did not tell what DWDM multiplexer you are using. A 44 channel
>> DWDM multiplexer from Fiberstore can have up to 4.5 dB insertion loss. Yo=
u
>> might have two of those on your link for a total of 9 dB loss. Your 80 km=
>> module has a 23 dB link budget, so this leaves you with 23-9 =3D 14 dB
>> budget. If your fiber has 0.25 dB loss per km, that is only 56 km.
>>=20
>> Regards,
>>=20
>> Baldur
>=20
