I'm wondering what everyones thoughts are in regards to FTTH using Active
Ethernet or Passive. I work for a FTTH Provider that has done Active
Ethernet on a few networks so I'm always biased in discussions, but I don't
know anyone with experience in PON.
I've read before that almost all PON technology is proprietary, locking you
into a specific hardware vendor. However I think this is changing or has
already changed, opening PON up for interoperability. Can anyone confirm
this?
I'm wondering what everyones thoughts are in regards to FTTH using Active
Ethernet or Passive. I work for a FTTH Provider that has done Active
Ethernet on a few networks so I'm always biased in discussions, but I don't
know anyone with experience in PON.
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).
I've read before that almost all PON technology is proprietary, locking you
into a specific hardware vendor. However I think this is changing or has
already changed, opening PON up for interoperability. Can anyone confirm
this?
There are several actual PON standards out there:
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.
The suburban area where I live, mostly detached homes, has a service
density of around 1500 to 2000 residences per square mile. Practically
speaking, one or two dedicated fibers per residence at that density
means you're not going to get a 5 mile radius from your powered
equipment. Pi * 5^2 * 2000 residences * 2 strands per residence =
300,000 strands of fiber.
So you're going to deploy powered equipment to one hell of a lot of
non-customer field locations. Since most of those locations are not
carefully conditioned computer rooms, you're going to pay more for
ruggedized equipment too.
In that scenario, PON cuts the number of field locations in which you
have to maintain non-CPE powered equipment by an order of magnitude or
more. Perhaps even to zero. This improves system reliability and
yields a rather substantial savings on maintenance cost over time. Pi
* 5^2 * 2000 residences * 1 strand / 16 residences per strand = 9,800
strands of fiber, a much more manageable number.
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.
You don't need to supply more than a gig per household, so active gige (or 100meg) is enough to feed the household with their broadcast video needs. So yes, you will need 10GE to the node and 100/1000 to each household do this this kind of video.
PON only makes sense with low take-rates and high per-truckroll costs when I did the business case last time.
Another big advantage is in CO equipment. A 4-PON blade in a cabinet is
going to support on the order of 256 ONTs.
But you lose out on the CPEs, at least historically these were much more expensive than the 100FX/TX media converters available in the market.
You don't need to supply more than a gig per household,
"640K ought to be enough for anybody. " (oft mis-attributed to Bill Gates) Bill Gates - Wikiquote
If, 10 years ago (1999) when most internet-connected homes still used dialup, you had suggested that ISPs would be putting in gigabit services to homes, people would have laughed. Yet today, here we are talking about gig feeds. I wonder how much bandwidth homes will be using 10 years from now...
First commercial gige service available to residential here in Sweden was a few years after 2000 (be it only a few houses), I'd say at least 10% of swedish households can buy at least 100/10 service for less than 50USD a month and it's been like that for 5+ years (before that it was 10/10 for the same money).
Active ethernet means you upgrade CO and CPE and you can do whatever you need on the fiber strand to that household, whereas PON you need to upgrade everything that shares that passive stretch sharing 64-128 households.
Star networks (=active ethernet in the FTTH world) is the way to go, it's superior in the vast majority of use cases.
Once upon a time, Byron Hicks <bhicks@ots.utsystem.edu> said:
4k video feeds (the new High Def):
compressed: 1Gb/s
??
Current over-the-air HD (at a max of 1080i) is up to 19 megabits per
second (and most don't run it that high). Most cable systems compress
it more. 4k video is roughly 8 times the pixels than 1080i, but is
typically going to be compressed with better algorithms (MPEG4 is
roughly half the size of MPEG2), which would mean 4k video (at TV
quality) would be around 100 megabits per second.
These were the numbers presented at an Internet2 meeting about the 4k
testing happening between UCSD and UW. I'm not sure what compression
algorithm they were using for the test.
If, 10 years ago (1999) when most internet-connected homes still used
dialup, you had suggested that ISPs would be putting in gigabit
services
to homes, people would have laughed. Yet today, here we are talking
about gig feeds. I wonder how much bandwidth homes will be using 10
years from now...
s/be using/have access to/
One could make the argument that when we were doing dial-up over POTS the % utilization vs port speed was higher than today with packet switching to the curb. People have been lamenting the lack of for-profit apps that will actually each up these 100+ mb/s residential pipes (the "killer app").
One could further argue that the talk of gigabit pipes to the home has been ushered in by the cost-effectiveness of gigabit ethernet over SONET or other technologies and this is why we are seeing such a massive increase in the port speeds to customers. As a percentage of pipe available (discounting things like kiddie's using Torrent), I wouldn't be surprised to see that percentage drop. (Residential broadband folks chime in please).
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.
That's true but I'd hope it wouldn't be needed. A single residence wouldn't get anywhere near needing 1Gbps of video bandwidth. Even with MPEG2 and 50 HD STBs @ 19Mbps that would still leave 50Mbps for Internet. I don't know of anyone needing that much BW for video.
PON does present the possibility of doing and RF Overlay though which makes traditional RF possible. That's something our CATV guy talks about often. The RF wavelength gets spun off at the NID and outputted as traditional RF on coax. I've heard of similar things with limited WDM from the egress side of the active Ethernet switch to the NID but I haven't seen any in production.
Another big advantage is in CO equipment. A 4-PON blade in a cabinet is
going to support on the order of 256 ONTs.
This is something that I don't think many people have dealt with before. In our rural Active FTTH environment we're not hubbing all the fiber out of COs. Most of it hubs back to cabinets on the side of the road and from there gets put on an Ethernet ring which ultimately terminates in the COs. Because of this while we may have tens of thousands of strands out in the field we don't have anywhere near that amount in a single cabinet or CO. A lot of people think that Active FTTH means home-running ever strand back to a single CO and that's not generally the case. LECs usually deploy a distributed model with aggregation out in the field in cabinets or huts and then backhaul that back to the COs. This also means that fewer individual fiber ports get served out of any one location. So a cabinet might have 3-4 blades in individual chassis or it might have a 13-slot chassis with as many slots populated to meet the demand. It seems to work well. I see what you mean though with the port density and space savings. I think most deployments manage to avoid the hassle but I can see where extremely dense locations could run into trouble.
I'm wondering why despite all this comparatively magical speed
increase we have seen over the last decade, with 10 times better on
the horizon, we the customer ever get a 1:1 speed ratio?
In the case of PON, WDM is used to dedicate wavelengths on the strand for
different purposes - ingress, egress, RF overlay (as someone else
mentioned), TDM voice etc.
You could deploy 2 or 3 strands and get more bandwidth to the customer,
using perhaps less expensive hardware, or you could maintain fewer strands
in the ground and depend on equipment manufactures to maintain an adequate
growth in bandwidth capabilities.
I'm wondering why despite all this comparatively magical speed
increase we have seen over the last decade, with 10 times better on
the horizon, we the customer ever get a 1:1 speed ratio?
speed kills...
actually, the killer here is PMTU... there is almost no
way to effectively utilize the BW when the MTU is locked to
1500 bytes.
You could deploy 2 or 3 strands and get more bandwidth to the customer,
using perhaps less expensive hardware, or you could maintain fewer
strands
in the ground and depend on equipment manufactures to maintain an
adequate
growth in bandwidth capabilities.
Neither approach is going to work for everyone.
--
Dan White
At my previous job we were deploying a hybrid system - a mix of active and
PON depending on the requirements of the customer.
For the active systems it wasn't homerun fiber back to the main CO - we had
a nice ring of fiber to key locations in the City and then we would place a
ped where the spurs would connect to.
Top that off with a CISCO Wireless Mesh overlay and no matter what speed
and mobility you needed you could get it somehow... Our only limit (at the
time I left) was upstream to the Internet.
These were the numbers presented at an Internet2 meeting about the 4k
testing happening between UCSD and UW. I'm not sure what compression
algorithm they were using for the test.
"The Italian broadcaster, RAI, demonstrated satellite broadcasting of
SHV at 140 Mbit/s from Turin to IBC."
Super Hi-Vision has a resolution of 4320x7860 (and also carries 22.2
channel sound). IIRC the video codec used was Dirac.
From the Dirac website:-
"In our first experiments, we managed to get excellent picture quality
at 128Mb/s, which sounds huge but is equivalent to just 4Mb/s for HDTV."