Re: [802.3BA] Discussion on 40G for => 10 km SMF

[Chris Cole <chris.cole@xxxxxxxxxxx>]

Title: Re: [802.3BA] Discussion on 40G for => 10 km SMF

Gary,

 

You are generous with your reach allocation of 3km to 4km for simple 40G NRZ in the 1550nm window. ITU-T defines the 40G VSR (1550nm NRZ) reach as 2km (at 2dB path penalty) because that is the limit beyond which interoperability starts falling apart. 3km to 4km reach can only be achieved through careful tuning of transmitter parameters to match receiver parameters.

 

Unless "metro applications" includes small villages, 2km 8 wave transport is not very useful.

 

Chris

---

From: Gary Nicholl (gnicholl) [mailto:gnicholl@xxxxxxxxx]
Sent: Mon 8/11/2008 11:11 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] Discussion on 40G for ="" 10 km SMF

> -----Original Message-----
> From: Chris Cole [mailto:chris.cole@xxxxxxxxxxx]
> Sent: Friday, August 08, 2008 6:17 PM
> To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
> Subject: Re: [802.3BA] Discussion on 40G for ="" 10 km SMF
>
> Mikael,
>
> Your proposal for an easy to develop 40GE 8 wave transport
> might benefit from additional technical due diligence.
>
> With 20nm spacing, it is not possible to get 8 wavelengths
> into the 1310nm window; there are only 5 wavelengths
> available. In any case, other then for the 1311nm wavelength,
> all other CWDM wavelengths (in all
> bands) have severely limited reach because of 40G dispersion effects.



To put this into context, a 40G serial solution running in the 1550nm
window is (dispersion) limited to a distance of only 3-4km
(significantly less than even the 10km Mikael is looking for). This
compares to a distance of 80+km at 10G .

Bottom line is that 40GE colored optics will require something other
than a simple serial solution (as Chris pointed out in an earlier
email). 


Gary ....



>
> Chris
>
> -----Original Message-----
> From: Mikael Abrahamsson [mailto:swmike@xxxxxxxxx]
> Sent: Friday, August 08, 2008 2:55 PM
> To: Chris Cole
> Cc: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
> Subject: Re: [802.3BA] Discussion on 40G for ="" 10 km SMF
>
> On Fri, 8 Aug 2008, Chris Cole wrote:
>
> > There is nothing about any approach being considered for
> 40GE 10km SMF
> > that helps DWDM better then the other being considered.
>
> I am not primarily talking about DWDM, I am talking about
> 10km (and perhaps up to 40km) SMF light with CWDM wave
> spacing (20nm) for metro applications.
>
> Enabling fairly easy development of 40GE 8 wave transport
> without transponders (colored optics directly into external
> CWDM mux) tips the balance for me in favor of 40GE serial, if
> cost projections are similar for 40GE serial vs 4x10GE CWDM.
>
> --
> Mikael Abrahamsson    email: swmike@xxxxxxxxx
>