[160171] in North American Network Operators' Group
Re: Muni fiber: L1 or L2?
daemon@ATHENA.MIT.EDU (Jason Baugher)
Fri Feb 1 16:06:50 2013
In-Reply-To: <CAGbD49rHhz=PmqL-8a12OaK=zJE9iBTnb7ZeT=0k68azgdZusw@mail.gmail.com>
Date: Fri, 1 Feb 2013 15:04:18 -0600
From: Jason Baugher <jason@thebaughers.com>
To: Scott Helms <khelms@zcorum.com>
Cc: NANOG <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
I should clarify: Distance x loss/km + splitter loss. = link loss.
On Fri, Feb 1, 2013 at 3:03 PM, Jason Baugher <jason@thebaughers.com> wrote:
> I disagree. Loss is loss, regardless of where the splitter is placed in
> the equation. Distance x loss + splitter insertion loss = total loss for
> purposes of link budget calculation.
>
> The reason to push splitters towards the customer end is financial, not
> technical.
>
>
> On Fri, Feb 1, 2013 at 2:29 PM, Scott Helms <khelms@zcorum.com> wrote:
>
>> Owen,
>>
>> You're basing your math off of some incorrect assumptions about PON. I'm
>> actually sympathetic to your goal, but it simply can't work the way you're
>> describing it in a PON network. Also, please don't base logic for open
>> access on meet me rooms, this works in colo spaces and carrier hotels but
>> doesn't in broadband deployments because of economics. If you want to
>> champion this worthy goal you've got to accept that economics is a huge
>> reason why this hasn't happened in the US and is disappearing where it has
>> happened globally.
>>
>>
>> > Bottom line, you've got OLT -> FIBER(of length n) -> splitter ->
>> > fiber-drops to each house -> ONT.
>> >
>>
>> So far you're correct.
>>
>>
>> >
>> > All I'm proposing is making n really short and making "fiber-drops to
>> each
>> > house" really long.
>> > I'm not proposing changing the fundamental architecture. Yes, I
>> recognize
>> > this changes the economics and may well make PON less attractive than
>> other
>> > alternatives. I don't care. That's not a primary concern. The question
>> is
>> > "can PON be made to work in this environment?" It appears to me that it
>> can.
>> >
>>
>>
>> Here is where you're problems start. The issue is that the signal *prior
>> to being split* can go 20km if you're splitting it 32 ways (or less) or
>> 10km if you're doing a 64 way split. AFTER the splitter you have a MAX
>> radius of about 1 mile from the splitter.
>>
>> Here is a good document that describes the problem in some detail:
>>
>> http://www.ofsoptics.com/press_room/media-pdfs/FTTH-Prism-0909.pdf
>>
>>
>> Also, here is a proposed spec that would allow for longer runs post
>> splitter with some background on why it can't work in today's GPON
>> deployments.
>>
>>
>> http://www.ericsson.com/il/res/thecompany/docs/publications/ericsson_review/2008/3_PON.pdf
>>
>> --
>> Scott Helms
>> Vice President of Technology
>> ZCorum
>> (678) 507-5000
>> --------------------------------
>> http://twitter.com/kscotthelms
>> --------------------------------
>>
>
>
