last mile, regulatory incentives, etc

Thu Mar 22 22:15:56 UTC 2012

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