Does anyone have some experience to use dwdm monofiber mux/demux ( ex. fiberstore ) about 68km using a ADFA ? Have I to use a DCM( for chromatic dispersion ) on this distance? When I have to use a DCM ? Rodrigo Augusto Gestor de T.I. Grupo Connectoway http://www.connectoway.com.br <http://www.connectoway.com.br/> http://www.1telecom.com.br <http://www.1telecom.com.br/> * rodrigo@connectoway.com.br <mailto:rodrigo@connectoway.com.br> ( (81) 3497-6060 ( (81) 8184-3646 ( INOC-DBA 52965*100
On Wed, 22 Apr 2015, Rodrigo Augusto wrote:
Does anyone have some experience to use dwdm monofiber mux/demux ( ex. fiberstore ) about 68km using a ADFA ? Have I to use a DCM( for chromatic dispersion ) on this distance? When I have to use a DCM ?
You have to use DCM when the chromatic dispersion caused by your distance exceeds what your receiver optical module can handle. So the answer is "it depends". If you're using 1GBASE-DWDM optics then you'll be fine, if you use 10GBASE DWDM optics then it depends on the distance they were designed to handle, if you buy the 40km ones then you should have DCM. -- Mikael Abrahamsson email: swmike@swm.pp.se
Buy 80km sfp+ dwdm modules c21 and c51. On this scenario a don¹t 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 i¹m not sure this if I have a chromatic dispersion I have to use a DCM not a ADFA or a booster Right?! Rodrigo Augusto Gestor de T.I. Grupo Connectoway http://www.connectoway.com.br <http://www.connectoway.com.br/> http://www.1telecom.com.br <http://www.1telecom.com.br/> * rodrigo@connectoway.com.br ( (81) 3497-6060 ( (81) 8184-3646 ( INOC-DBA 52965*100 On 22/04/15 15:33, "Mikael Abrahamsson" <swmike@swm.pp.se> wrote:
On Wed, 22 Apr 2015, Rodrigo Augusto wrote:
Does anyone have some experience to use dwdm monofiber mux/demux ( ex. fiberstore ) about 68km using a ADFA ? Have I to use a DCM( for chromatic dispersion ) on this distance? When I have to use a DCM ?
You have to use DCM when the chromatic dispersion caused by your distance exceeds what your receiver optical module can handle.
So the answer is "it depends". If you're using 1GBASE-DWDM optics then you'll be fine, if you use 10GBASE DWDM optics then it depends on the distance they were designed to handle, if you buy the 40km ones then you should have DCM.
-- Mikael Abrahamsson email: swmike@swm.pp.se
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 much power you get on the other end. Also it is said that the laser will lose power over time. Second you need to think in terms of power budget, not distance. So you got 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. 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. You 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 = 14 dB budget. If your fiber has 0.25 dB loss per km, that is only 56 km. Regards, Baldur
I think the OP is asking about whether it should account for chromatic dispersion or not. Intramodal dispersion may very well be a limit on your link even 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 an OTDR and make the measurements. -- Evelio On Wed, Apr 22, 2015 at 1:51 PM, Baldur Norddahl <baldur.norddahl@gmail.com> 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 much power you get on the other end. Also it is said that the laser will lose power over time.
Second you need to think in terms of power budget, not distance. So you got 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.
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. You 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 = 14 dB budget. If your fiber has 0.25 dB loss per km, that is only 56 km.
Regards,
Baldur
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 -20dbi sensibility ... This scenario have a 4 channels... And i use 2 10gb channels... C21 and c22 on side A and c51 and c52 on side B.... Enviado via iPhone Grupo Connectoway
Em 22/04/2015, às 19:01, Evelio Vila <evelio@thousandeyes.com> escreveu:
I think the OP is asking about whether it should account for chromatic dispersion or not. Intramodal dispersion may very well be a limit on your link even 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 an OTDR and make the measurements.
-- Evelio
On Wed, Apr 22, 2015 at 1:51 PM, Baldur Norddahl <baldur.norddahl@gmail.com> 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 much power you get on the other end. Also it is said that the laser will lose power over time.
Second you need to think in terms of power budget, not distance. So you got 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.
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. You 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 = 14 dB budget. If your fiber has 0.25 dB loss per km, that is only 56 km.
Regards,
Baldur
Remember, distance ratings are just generalizations. It all comes down to power budget. When fiber is laid there are slack loops for potential future service and for use if a cable is cut, splice cases -- because it's hard to work with a fiber spool with more than 5 miles of cable on it, other connectors, hand holes with slack coils, etc. If the route is 80km the actual fiber distance could be more like 100 or 120km with all of the slack. Then you add on DB loss for every splice and connector. As others have said, the only way to really know is to shoot it with a power meter and see what the end to end loss is, and then get the correct optics for the path you have On Wed, Apr 22, 2015 at 6:43 PM, Rodrigo 1telecom <rodrigo@1telecom.com.br> wrote:
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 -20dbi sensibility ... This scenario have a 4 channels... And i use 2 10gb channels... C21 and c22 on side A and c51 and c52 on side B....
Enviado via iPhone Grupo Connectoway
Em 22/04/2015, às 19:01, Evelio Vila <evelio@thousandeyes.com> escreveu:
I think the OP is asking about whether it should account for chromatic dispersion or not. Intramodal dispersion may very well be a limit on your link even 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 an OTDR and make the measurements.
-- Evelio
On Wed, Apr 22, 2015 at 1:51 PM, Baldur Norddahl < baldur.norddahl@gmail.com> 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 much power you get on the other end. Also it is said that the laser will lose power over time.
Second you need to think in terms of power budget, not distance. So you got 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.
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. You 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 = 14 dB budget. If your fiber has 0.25 dB loss per km, that is only 56 km.
Regards,
Baldur
On Wed, 22 Apr 2015, Rodrigo Augusto wrote:
Buy 80km sfp+ dwdm modules? c21 and c51. On this scenario a don¹t 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 i¹m 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
On 04/23/2015 12:01 AM, Mikael Abrahamsson wrote:
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.
Should you find yourself on the edge (or unknowing) of the dispersion tolerance of the 80km modules you would like to use, 120km-tolerant modules are also somewhat readily available these days, including from fiberstore. They don't have the power to shoot 120km without external (generally mid-span) amplification, but they will tolerate the accumulation of ~120km worth of chromatic dispersion. Thus, you can do 120km of fiber (typ.) with EDFAs in the span for power budget reasons but without an accompanying DCM at each hop. Since the commodity DCMs cost almost as much as commodity mid-power EDFAs, these days, that could be a significant cost savings. As always when buying whitebox/commodity networking goods, careful review of the specifications and testing in your proposed application is in order. -- Brandon Martin
Rule of thumb is you need Dispersion compensation for any single span over 60Km. 10G/STM64 has a CD Tolerance of 1176 ps/nm, 40G/STM256 has a CD tolerance of 73.5ps/nm but you don't want your dispersion number to ever go negative. If it's a single-span only rule of thumb is use the next size smaller than the measured fiber distance maintaining at least 10km on the bottom end, 65km would use a 40km dcm 70km would use a 60km dcm. As long as each site does OEO you can do Dispersion hop-by-hop, if any node on the ring pass a channel through, or is only optically amplified, you need to calculate DC along the entire path, ensuring that the DC number never goes negative. DC should be inserted between the egress of the combining mux and the post-amp to maximize your launch power. Try to stay away from channel-by-channel DCM, it gets really messy as the system grows. And remember always clean-scope-clean! -----Original Message----- From: NANOG [mailto:nanog-bounces@nanog.org] On Behalf Of Brandon Martin Sent: Thursday, April 23, 2015 2:36 AM To: nanog@nanog.org Subject: Re: DWDM and EDFA and DCM On 04/23/2015 12:01 AM, Mikael Abrahamsson wrote:
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.
Should you find yourself on the edge (or unknowing) of the dispersion tolerance of the 80km modules you would like to use, 120km-tolerant modules are also somewhat readily available these days, including from fiberstore. They don't have the power to shoot 120km without external (generally mid-span) amplification, but they will tolerate the accumulation of ~120km worth of chromatic dispersion. Thus, you can do 120km of fiber (typ.) with EDFAs in the span for power budget reasons but without an accompanying DCM at each hop. Since the commodity DCMs cost almost as much as commodity mid-power EDFAs, these days, that could be a significant cost savings. As always when buying whitebox/commodity networking goods, careful review of the specifications and testing in your proposed application is in order. -- Brandon Martin
participants (8)
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Baldur Norddahl -
Brandon Martin -
Evelio Vila -
Jameson, Daniel -
Mikael Abrahamsson -
Rodrigo 1telecom -
Rodrigo Augusto
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Shawn L