Re: Muni fiber: L1 or L2?

[Mikael Abrahamsson <swmike () swm pp se>]

On Wed, 6 Feb 2013, Scott Helms wrote:

> The cost difference in a single interface card to carry an OC-3/12 isn't 
> significantly more than a Gig-E card.  Now, as I said there is no 
> advantage to doing ATM, but the real cost savings in a single interface 
> are not significant.

There has always been a substantial price difference for ATM/POS compared 
to ethernet.

But when designing ETTH networks, the cost saving is in the use of very 
simple devices. L2/L3 switches all the way. No tunneling, no fancy 
encap/decap Q-in-Q etc. Enough intelligence to do the BCP38 stuff to 
prevent spoofing, MitM-attacks, nothing more, but still deliver needed 
services over unicast and multicast.

So as soon as the design contains any of the words L2TP, PPPoE/A, ATM, 
POS, OC-whatever, xPON or anything like it, you're incurring unneccessary 
cost, especially for high bw services.

The most inexpensive device to L3-terminate 10GE worth of traffic from a 
few thousand customers is in the few thousand dollar range, what's the 
cost if you want to do the same using L2TP or PPPoE ? What about ATM? I 
don't even know if ATM on OC192/STM64 is even widely available. My guess 
is anyhow that you're not looking at a device that costs at least 5-10x 
the cost.

Designing a fiber plant very much like the traditional copper plant, ie 
aggregating thousands of households in a single pop, and letting "anyone" 
terminate that fiber, is a very future proof and scalable approach. The 
fiber can be lit up using any technology (active p-t-p ethernet, or PON, 
or whatever is desired), this doesn't have to be chosen at time of 
actually drawing the fiber. Yes, it's a high initial cost but I firmly 
believe that over tens of years of lifetime of the fiber, this cost is 
lower than other solutions.

--
Mikael Abrahamsson    email: swmike () swm pp se