In a message written on Sun, Mar 25, 2012 at 05:29:04PM +0100, Nick Hilliard wrote:
most of the expense of laying fibre is associated with ducting + wayleave. Once you have that in place, blowing new fibre is relatively inexpensive. So rather than amortising the cost according to the lifetime of the fibre, it makes much more sense to amortise over the lifetime of the ducting.
Maybe. In rural deployments it's much more likely the fiber is aerial, it's far cheaper to attach to existing poles with few cables on them than it is to bury the fiber. Even in urban areas where buried duct is the norm, being able to use old ducts varies a lot with the geography and how active the area is to other development. I've seen plenty of ducts where it had been cut and repaired several times before use that running a new cable through it was impossible and it simply had to be replaced. In other locations 20 years later a new cable goes through like butter. But I think it's all a bit of a tangent; when talking about _residential_ fiber it's prudent to run 2-6 strands to every home day one, and then, well, there's basically never a point in running more. The chance of blowing more fiber down the duct later is near zero. It's also why I'm not a fan of *PON schemes, eliminate the splitter and run a single star topology. 20 years from now Petabit optics will look different than today's GigE in some way, but I'll bet money they are tuned to run on single mode fiber. They may not like the splitters and the like though. By doing a star back to a wiring center you enable all technologies. GPON today, direct GigE or 10GE where necessary, and all future technologies. -- Leo Bicknell - bicknell@ufp.org - CCIE 3440 PGP keys at http://www.ufp.org/~bicknell/