FTTH Active vs Passive

Dan White dwhite at olp.net
Tue Dec 1 11:14:35 CST 2009

On 01/12/09 10:43 -0600, Justin Shore wrote:
> Active is the way to go.  Passive is merely a stepping stone on the way  
> to active.  Passive only makes sense (in some cases) if you are 1) fiber  
> poor and 2) not doing a greenfield deployment.  If you have the fiber to  
> work with or if you are building a FTTH plant from scratch go with  
> active.  The only real proponents of PONs are the RBOCs who are  
> exceedingly cheap, slow to react, and completely unable to think ahead  
> (ie, putting in an abundance of fiber for future use instead of just  
> enough to get by) and some MSOs who don't dread and loathe shared  
> network mediums like CATV and PON (whereas those from a networking  
> background would never ever pick such a technology).
> Few vendors will ever admit that they interop with another vendor's gear  
> though.  They don't want you to buy their optical switches (which have a  
> small markup) and someone else's ONTs (which typically have a much  
> greater markup).  In some cases even though that adhere to the standards  
> to a point they diverge and go proprietary for things like integrating  
> voice or video into the system.  That could cause management and/or  
> support issues for you at some point in the life of the product.  
> Personally I'd go with a vendor that offers the complete solution  
> instead of piecing one together.
> PON has some popularity in MDUs.  The splits are easy to manage because  
> they're all in one location.  Bandwidth needs are typically on the low  
> end in MDUs due to a lack of businesses (bandwidth being a severe  
> future-proofing problem for PON).  PON's biggest limitations for us is  
> the distance limitations.  We're deploying FTTH in the rural  
> countryside, not in a dense residential neighborhood.  PON has very  
> specific distance limitations for each split and cumulative across all  
> splits that make rural deployments extremely difficult.  The price  
> difference between Active and PON is negligible at this point and in  
> many cases cheaper for active.  Go with active for FTTH.  You won't  
> regret it.

All valid points. Deploying a strand to each customer from the CO/Cabinet
is a good way to future proof your plant.

However, there are some advantages to GPON - particularly if you're
deploying high bandwidth video services. PON ONTs share 2.4Gb/s of
bandwidth downstream, which means you can support more than a gig of video
on each PON, if deploying in dense mode.

Another big advantage is in CO equipment. A 4-PON blade in a cabinet is
going to support on the order of 256 ONTs.

Dan White

More information about the NANOG mailing list