ajschmitt
join:2005-11-30
| reply to ronpin
Re: My Take on Lightspeed
said by ronpin  :Each of those 40 fibers from the Verizon CO to the splitter pedestal are terminated in optical OLT ports in the CO that mux up to 32 users each. So those 40 strands will serve up to (40x32) 1280 homes -- near the pedestal. Not according to the VZ lineman I spoke to. He said the cable that went from the splitter box (which serves maybe 100 homes) is practically unused.... that they just pull fat fiber. I wish I knew exact fiber counts, but this would mean that only 10% of the fiber is lit, and many extra OLT ports could be added in the future. Or, some users could be moved to 1:1 connections.
said by ronpin :WDM-PON is actually the term being used to describe the current 3 laser BPON system. "DWDM" (Dense Wavelength Division Multiplexing) is "in search of an application" -- in the Last Mile. The ITU "color grid" defines 96 wavelengths in the 1500nm "C" band for DWDM . Really, only 32 wavelengths are needed to give each current FiOS user a unique "virtual fiber". I did err earlier (above) when I cited uDWDM as the method needed to do that (ultra-DWDM defines 1024 lambdas with much tighter spacing). I think we are splitting hairs on terminology. I'm talking about what was announced by Korea Telecom and enabled by Novera Optics
»noveraoptics.com/htmls/company_overview.html |
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ronpin
Imagine Reality
join:2002-12-06
Nirvana
 ·AT&T Southwest
| reply to ajschmitt
said by ajschmitt :One thing you are missing - VZ runs a a multiple fiber bundle (like 40) to the splitter cabinet. Even though one of those fibers are being used, nothing precludes removing the splitter and then wiring up the home runs 1:1. At the very least, it would be easy to further partition the network to reduce the number of users per fiber. And if none of this works, there is always WDM-PON, though I think it is a technology in search of an application. Each of those 40 fibers from the Verizon CO to the splitter pedestal are terminated in optical OLT ports in the CO that mux up to 32 users each. So those 40 strands will serve up to (40x32) 1280 homes -- near the pedestal.
WDM-PON is actually the term being used to describe the current 3 laser BPON system. "DWDM" (Dense Wavelength Division Multiplexing) is "in search of an application" -- in the Last Mile. The ITU "color grid" defines 96 wavelengths in the 1500nm "C" band for DWDM . Really, only 32 wavelengths are needed to give each current FiOS user a unique "virtual fiber". I did err earlier (above) when I cited uDWDM as the method needed to do that (ultra-DWDM defines 1024 lambdas with much tighter spacing).
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"Now is the time for all good men to come to the aid of their country" - and stop the NeoCons |
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ajschmitt
join:2005-11-30
| reply to ronpin
One thing you are missing - VZ runs a a multiple fiber bundle (like 40) to the splitter cabinet. Even though one of those fibers are being used, nothing precludes removing the splitter and then wiring up the home runs 1:1. At the very least, it would be easy to further partition the network to reduce the number of users per fiber.
And if none of this works, there is always WDM-PON, though I think it is a technology in search of an application. |
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ronpin
Imagine Reality
join:2002-12-06
Nirvana
·AT&T Southwest
4 edits | reply to nunya
Passive FTTP will be obsolete for a future FTTN upgrade. You'll recall FTTP was designed to handle voice, video and data -- all on separate lasers (1310nm, 1490nm, 1550nm). Also, the passive feature allows a 6 mile range, no field electronics and 1x32 passive splits per fiber (to reduce trunk fiber counts)
None of those features are needed to upgrade LightSpeed. The FTTN architecture already combines video and data onto the same pipe. Voice/VoIP is also just data.
The close-in FTTN nodes (less than 5000 feet) remove the need to reduce fiber trunk strand counts and thus the need to share fibers via 1x32 passive splits per fiber. Why? In the FiOS "centralized splitter" implementation -- a passive splitter pedestal is placed within 5000 feet of homes. Individual strands are then "homerun" to each house -- via high-count ribbon cables. This is precisely analogous to running high-count ribbon cables from the FTTN nodes to homes -- to replace the current copper pairs.
So, if you followed that terse explanation -- no shared/split fiber or multi-laser (WDM) "FTTP" will be needed at all. What remains is actually a classic "active" fiber distributed "star" network. Fiber -- in this case -- adds [only] OCxxx or gigE speeds for HDTV and data applications. The distance feature of fiber will not be needed to overlay an old close-in FTTN network.
Get it? an actual FTTP overlay to replace a FTTN network would be silly. An "active fiber" network can precisely duplicate the old FTTN network -- only with virtually unlimited future capacity. Cheap "media converters" can even maintain a classic copper signal at each homesite if desired (300' max range) One advantage of active fiber is "symmetrical upload speeds" will be available. FTTP has asymmetrical upload speeds due to the need to share upload time slots on the shared fiber. No problem on "active fiber". So SBC will wind up with a "better" fiber network than Verizon's FiOS (unless FiOS switches to uDWDM VC's -- unique lambda's for each user on a currently shared 32 user fiber strand -- a unique virtual fiber for each user).
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"Now is the time for all good men to come to the aid of their country" - and stop the NeoCons |
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