nanog mailing list archives

Re: FTTH Active vs Passive


From: Dan White <dwhite () olp net>
Date: Tue, 1 Dec 2009 11:14:35 -0600

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


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