[151485] in North American Network Operators' Group
Re: last mile, regulatory incentives, etc
daemon@ATHENA.MIT.EDU (Masataka Ohta)
Thu Mar 22 18:17:43 2012
Date: Fri, 23 Mar 2012 07:15:56 +0900
From: Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp>
To: nanog@nanog.org
In-Reply-To: <CAP-guGX7B-XHiC0-54RWo9H22NFp-ChKBen1zWSPFsTWDrVYkA@mail.gmail.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
William Herrin wrote:
> PON (e.g. FIOS) is similar to CWDM.
If you are not talking about WDM PON, no, not at all.
> The PO in PON is Passive Optical.
> As in a glass prism-like device with no electronics.
The passive optical device of usual PON is not a prism but a
splitter.
The entire optics is shared by all the subscribers sharing
a fiber.
Thus, the problem is collision avoidance of simultaneous
transmission, which makes PON time shared with L2 protocols.
> So, you share fiber by having one guy control one wavelength (color,
> e.g. red) and another guy control another wavelength (e.g. blue).
That's not a usual PON but WDN PON.
> Or, you could share at a different level: ethernet packets.
That's where usual PON can be shared. But, it costs a lot,
as much as sharing at L3.
Masataka Ohta
