On Wed, Dec 12, 2018 at 7:16 AM Ross Tajvar <ross@tajvar.io> wrote:

I don't really have any advice to offer here (sorry), but I am curious how setting up a GPON LAN would save money vs just getting cheaper switches...and also what a GPON LAN even looks like. Does every office or classroom have an ONT?

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Hi Ross Every room will have a small switch style ONT. These devices can have a small battery for power outages and provide PoE to voice over IP phones. Typically the ONT switch has from 4 to 24 copper ethernet ports. The building will have a tree like structure of splitters. For example if there are four floors, you might have a 1:4 splitter at the entrance to the building, then on each floor you could have another 1:4 splitter to four sections and then in each section you might have a 1:8 splitter to provide network to 8 rooms. Of course this could be designed in many different configurations depending on the needs and layout of the building. The maximum combined splits is 128. In my example we had 4*4*8 = 128 splits. If you need more, you will deploy additional OLT ports with new splitter trees. As to cheaper I can not say. I am not selling any of this stuff. I can say that the price for a small 4 port ONT switch is about USD 50 to 100. The battery is extra but not very expensive. It is just a small cell phone style battery that plugs directly into the ONT, not a full UPS system. It is possible to build this with redundancy. I suspect it is rarely done. The redundancy works in the way, that the 1:8 splitter can be replaced with a 2:8 splitter. This has the same power budget, but you get two input ports to the splitter. Only one can be active at a time. The GPON OLT switch needs to coordinate which of the input ports is used. How that is done is vendor specific. You would build an independent backbone tree for the second input port to the splitter. It is possible one should not choose this system over a traditional approach, but the people screaming "rip it out" are out of line IMHO. It would be a huge expense to rewire a building with copper and they already got a working fiber system. Much can be said about GPON but it is actually quite stable and easy to manage. Compared to the traditional approach, you will only have one centralized GPON switch to manage. All the small ONT switches are managed through this. Complaints about the interface is vendor specific. Because there is only one centralized switch, it would be fairly cheap to switch vendor. Much cheaper than to rewire with copper in any case. Regards, Baldur

On Wed, Dec 12, 2018 at 10:16 AM Aled Morris <aled.w.morris@googlemail.com> wrote:

On Wed, 12 Dec 2018 at 06:48, Baldur Norddahl <baldur.norddahl@gmail.com> wrote:

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It is possible one should not choose this system over a traditional approach, but the people screaming "rip it out" are out of line IMHO. It would be a huge expense to rewire a building with copper and they already got a working fiber system. Much can be said about GPON but it is actually quite stable and easy to manage.

I don't think anyone is saying replace the existing fibre with copper, but instead to run cheap SFP-equipped switches in basically the same topology as the GPON you described.

That would still be costly in time and money with no obvious gain. You would get some downsides however. Now you have many single point of failures, a lot of small switches at the splitting points that need power backup and be managed. And exactly the same issue with PoE that someone raised. Only you will find more GPON ONT switches that already have the PoE with a battery build in, because those devices where made to answer that. Again not saying that you would make a new build in any particular way, but to rip anything out of a brand new build requires justification. The original poster might indeed have justifications, but the people recommending to "rip it out" does not appear to have anything, but that this is GPON technology. If your justification is that you only want to work with technology known to you, then it is maybe you that needs to be replaced. It is certainly possible to build something close to the GPON system using WDM instead. It is going to be more expensive. GPON splitters are very cheap, WDM splitters less so and the DWDM SFP modules way more expensive than the typical ONT. CWDM modules can be the same price as the ONT but you need to add a switch to that. You will also have a problem with the multi level tree approach.

For a new build, less splitting and more copper in-building would be cheaper and easier.

Maybe. Those big fat copper runs get unwieldy and take up a lot of space. That GPON system might have a 12 fiber, 3 mm cable as the backbone and a maximum of 8 drop cables (2-3 mm) from the splitter. The drop cables are much smaller than cat 6 cabling. Regards, Baldur

On Wed, Dec 12, 2018 at 7:51 PM William Herrin <bill@herrin.us> wrote:

On Tue, Dec 11, 2018 at 10:47 PM Baldur Norddahl <baldur.norddahl@gmail.com> wrote:

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Compared to the traditional approach, you will only have one centralized GPON switch to manage. All the small ONT switches are managed through this. Complaints about the interface is vendor specific. Because there is only one centralized switch, it would be fairly cheap to switch vendor. Much cheaper than to rewire with copper in any case.

Except you won't have one central GPON switch because LANs change incrementally.

In my experience, a PON network is extremely flexible. Our FTTH network is ever expanding and there is no master plan. Whenever people in existing areas decide to buy our product or whenever people in a new area decides to take a vote to get us in their area, the network will expand as needed. Often we will discover that we could not make a planed crossing because of something in the ground, but we can just change plans and do it another place. We have a competitor that decided to use p2p (point to point ethernet over fiber) instead and I have watched how they are struggling because they had to plan everything from the outset, and we didn't. The reason being that we use very little fiber for our backbone and can afford to change plans constantly. They need to backhaul hundreds or thousands of fiber strands to the central point, where they have the switches.

That throwback in office 412 with the fax machine? Can't simply buy him a pots line. You get to futz with fax over the converged phone system.

GPON is actually ATM and will provide hard realtime bandwidth guarantees. ISDN delivery over GPON is part of the standard. You will reserve 2x64 Kbit/s channels and GPON guarantees that will always be 100% available with no dropped frames and no jitter. You can do fax, modems, anything that the public phone service will carry over ATM. I have not personally tried this out as fax and modems are completely dead in my part of the world and nobody cares. But I have had a ONT (from Zhone no less) with ISDN ports (not POTS) and thought they are crazy.

Speaking of the converged phone system, you're now committed to VoIP on a VLAN. When you decide you want to switch to a physically separated network for the phones, well, that's too bad because your cabling infrastructure doesn't make that possible.

Nothing stops you from deploying two independent GPON networks, one for ISDN service and the other for data service. Typically the drop cables will be at least 2 fibers (GPON runs on a single fiber) so you would not need to change anything. In my example the backbone would need a maximum of 7 fibers. With a duplicated GPON network, that would be 14 fibers in the backbone. Personally I think duplicated networks are silly. But who am I to decide?

The AV lab gets screwed. You're running the coax they need through the noisy electrical riser because you didn't build dedicated comms risers and closets. Naturally nobody checked with them so you don't yet realize they can't do what they need to do with video over IP equipment.

Fiber will transmit anything that goes on coax as analog signals. Typically on 1550 nm. The converters are dead cheap and are purely analog devices. This is how we deliver TV on a FTTH GPON network. GPON uses 1310 nm for upstream data, 1490 for downstream data and 1550 nm for analog TV. When I say analog TV that is really DVB digital signal these days, but the equipment does not know any of that and just transmits it as an analog signal. Many GPON ONT for residential use come with a coax TV out port that can be turned on and off remotely, so the ISP can control TV delivery. Some also have build in filters that can be remote controlled, so you can have multiple TV packages using the usual system of filtering frequencies on the coax.

And what will you do in 5 years when they want the computer lab in 204 upgraded to 100Gig? Maybe run some fiber all the way back to the campus head end because as expensive as that is, it's still cheaper than replacing the OLT with 100-gig capable equipment and then replacing all the ONTs in the building because oops, there's no 100 gig OLT compatible with the old ONTs and you'd have to take the building down for a week to forklift-upgrade the whole mess.

One advantage of a fiber to the desktop solution is that you have fiber to every room. You just move a drop cable from the splitter and to a pair of backbone fibers. With this you can get a dedicated connection from any room to any other room including back to your data center. Yes you will have extra dark fibers available, anything else would be stupid.

Folks have advised Nick rip it out now because they foresee the slow-motion train wreck on its way. That may be extreme, but certainly he should take immediate action to preserve his options. For example, I would demand the creation of comms closets and risers before the building opened and I'd threaten to quit if they weren't. At least then the inevitable modifications can be structured and planned instead of turning in to an ad-hoc mess.

This is out of line IMHO. Hopefully they did add in extra conduits so you could do some special cable runs (including some copper and coax), if needed. But if they did not, it would be the responsibility of management, not yours. It also has nothing to do with fiber nor GPON. Plenty of copper builds have a severe lack of space for future proving. If they did the fiber build in the recommended way, there will be ducts prepared for fiber blowing, so one quickly can add more fiber cabling. I find it silly to threaten to quit if they wont make closets, that are then going to be empty. Regards, Baldur

Lower power consumption of electronics and the fact that most (not all) deployments don't need more than 10 megs committed to them, so share a big pipe and burst away. 1U can have 256 endpoints easily and consume less power than a regular switch. ----- Mike Hammett Intelligent Computing Solutions Midwest Internet Exchange The Brothers WISP ----- Original Message ----- From: "Alfie Pates" <alfie@fdx.services> To: nanog@nanog.org Sent: Wednesday, December 12, 2018 3:34:29 PM Subject: Re: Enterprise GPON / Zhone Questions The discussion was regarding an in-building LAN - residential access networks/WANs are a wholly different beast and GPON is fantastically suitable for that particular problem. There is, however, a reason that a lot of new mixed-use (business && residential) WAN fibre deployments end up building a home-run dark fibre network for business use and overbuilding with GPON for residential use - the 1-1 mapping of end users to patch points/flexibility points makes for a vastly more future-proof network. I think we often underestimate just how long the networks we install stick around. I ordered a 10Gbit/s service not too long ago over the very same fibre that was used to serve 2Mbit/s connections in the mid 90s: I'm not kidding, the fibre was physically disconnected from an old, derelict 2Mbit/s SDH network termination and plugged into a brand new 10Gbit/s EDD. GPON is cool, definitely - I've worked on very large scale GPON deployments before, and it is definitely a very useful technology that allows us to affordably deploy high-bandwidth consumer and small-business connectivity. However - it is a compromise, and I don't think you're gaining anything by running GPON versus the tried-and-tested method of active, switch-based aggregation, especially compared to the sacrifices you make deploying a passively-aggregated network. As I said before - I wouldn't stake my reputation on it. ~A

On Wed, Dec 12, 2018 at 12:09 PM Baldur Norddahl <baldur.norddahl@gmail.com> wrote:

On Wed, Dec 12, 2018 at 7:51 PM William Herrin <bill@herrin.us> wrote:

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On Tue, Dec 11, 2018 at 10:47 PM Baldur Norddahl <baldur.norddahl@gmail.com> wrote:

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Compared to the traditional approach, you will only have one centralized GPON switch to manage. All the small ONT switches are managed through this. Complaints about the interface is vendor specific. Because there is only one centralized switch, it would be fairly cheap to switch vendor. Much cheaper than to rewire with copper in any case.

Except you won't have one central GPON switch because LANs change incrementally.

In my experience, a PON network is extremely flexible. Our FTTH network [...]

Exactly, your FTTH network. PON wouldn't exist if it didn't have valuable use scenarios. Like an FTTH network. I was discussing Nick's scenario which is NOT an FTTH network. It's an in-building LAN with fiber runs measuring in tens or hundreds of feet (not miles) behind walls (not up on accessible utilities poles or down in accessible conduits) with screwy in-wall ONTs (not the user's responsibility to power) stuffed in a space that doesn't dissipate heat well. YOUR use of PON makes reasonably good sense.

One advantage of a fiber to the desktop solution is that you have fiber to every room. You just move a drop cable from the splitter and to a pair of backbone fibers.

Did it read to you like Nick's installation had drop cables of non-trivial length from easily accessed splitters? It didn't read that way to me.

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I would demand the creation of comms closets and risers before the building opened and I'd threaten to quit if they weren't. At least then the inevitable modifications can be structured and planned instead of turning in to an ad-hoc mess.

This is out of line IMHO. Hopefully they did add in extra conduits so you could do some special cable runs (including some copper and coax), if needed.

Nick said they did not create comms closets or a comms riser.

But if they did not, it would be the responsibility of management, not yours. It also has nothing to do with fiber nor GPON. Plenty of copper builds have a severe lack of space for future proving.

To an internal user, internal IT *is* part of the management complex. They're the ones who get to choose your password length and VPN rules. They make choices which are enforced on you, hence management.

If they did the fiber build in the recommended way, there will be ducts prepared for fiber blowing, so one quickly can add more fiber cabling.

If they did the fiber build in anything reasonably close to the recommended way there would be ducts connected to comms closets holding the splitters. He's already told us there are no comms closets. Regards, Bill Herrin -- William Herrin ................ herrin@dirtside.com bill@herrin.us Dirtside Systems ......... Web: <http://www.dirtside.com/>

On 12/12/18 10:51 AM, William Herrin wrote:

The AV lab gets screwed. You're running the coax they need through the noisy electrical riser because you didn't build dedicated comms risers and closets. Naturally nobody checked with them so you don't yet realize they can't do what they need to do with video over IP equipment.

There are double-shield coax solutions for noisy risers. The outer shield is grounded to the conduit, while the inner shield is grounded at the source equipment. One has to be sure that the voltage differential between shields is kept as low as practical, which means paying attention to grounding for the conduit AND equipment.