Muni fiber: L1 or L2?

Wed Feb 6 00:17:19 UTC 2013

Scott Helms wrote:

>> They are not soo different, as long as you try to recover initial
>> cost not so quickly, which is why copper costs about $10/M or so.

> I know several dozen companies that do this kind of construction and they
> don't agree.

That is, they are trying to recover initial cost quickly.

>> And, you can see the slide contain "POP Active Equipment Cost",
>> which you thought "most of the cost is in lighting the fiber",
>> is already included.

> Google is making their own access gear.  Their economy is very very
> different from all of us here.

If you think google access gear is much less expensive than others,
let google be the dominant supplier of the access gear for all of us.

>> If you throw away optical MDF, there is no point to discuss
>> L1 unbundling.
>>
> 
> OK, historically the main distribution frame was where all of the copper
> pairs came into a central office

which means they have enough space to accommodate optical MDF.

> note that a phone company often had
> several central offices to cover their territory in the time before there
> were remotes (Digital Loop Carriers).

Each CO has its own MDF, where competing ISPs must have their
routers.

No different from competing ISPs using DSL or PON.

> Today even when you home run all of
> your fiber connections you bring it to a central patch panel(s) which
> really doesn't look like a main distribution frame.

If so, it is merely because they want to make L1 unbundling difficult.

>>>> Surely, transition from copper to fiber is not trivial, but it
>>>> helps a lot that fiber cables are thinner than copper cables.
>>
>>> Really, so you think that the thickness of the cable has an impact on how
>>> much it should cost?  So, tell you what I'll exchange some nice thick
>>> 10 gauge copper wire for 4 gauge platinum, since its much thinner that
>>> ought to be a good trade for you, right?  ;)
>>
>> My point is that a conduit capable of storing additional 10 guage
>> copper can, instead, store 10 guage fiber.
>>
>> Or, if you assume a conduit without any extra space, upgrading to
>> PON is also impossible.

> OK, twisted pair cabling isn't run in conduit.

Each fiber in an access cable, neither.

> You cannot remove the twisted pair in whole or
> part and then run fiber through that cabling.

Are you saying you can remove a fiber from an access cable?

No, you can't.

Well....., it is not impossible if you use quite fatty cable in
which each fiber is stored in its own conduit. But, it costs a lot.
Worse, if a cable is cut, you must repair all the conduit to be
air tight again, which means it is practically impossible.

> You can of course use the
> same trench IF you have buried cable and there is room.

There is room for another cable mostly always, because, without
the room, you can not replace copper cables without much service
interruption.

To replace a damaged copper cable without much service
interruption, you have to lay a new cable before removing the
damaged cable.

	                                      Masataka Ohta