GPON Limitations

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UrbanNZ14

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#196642 7-Jun-2016 18:59

As I understand how Gigabit Passive Optical Networks operate, the maximum shared bandwidth per OLT port is of 2.488Gb/s downstream and 1.244 Gb/s upstream, shared between 24 ONTs. If that is the case, then the maximum uncontended bandwidth is 103Mbps downstream and 51Mbps upstream per ONT. Obviously the CIR is quite low.

I just have confusion as to speed profiles such as 200/200. Let's say that all 24 fibre connections from the optical line splitter are in service and they are provisioned with speeds of 100 and 200Mbps. If everyvone were saturating their fibre connection then wouldn't that degrade your available bandwidth. Or, does TDM help in someway to overcome that limitation. And lastly are the Duniden gigatown plans delivered over GPON or is it P2P.

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#1567339 7-Jun-2016 18:59

Hello... Our robot found some keywords in your post, so here is an automated reply with some important things to note regarding broadband speeds.

If you are posting regarding DSL speeds please check that

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Most of the problems with speed are likely to be related to internal wiring issues. Read this discussion to find out more about this. Your ISP is not intentionally slowing you down today (unless you are on a managed plan). Also if this is the school holidays it's likely you will notice slower than usual speed due to more users online.

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Aredwood

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#1567376 7-Jun-2016 19:09

Chorus only run a max of 16 customers per fibre. At least they do in the newer areas. Also it is unlikely that all customers who share a fibre will try maxing their connections at the same time. Be glad you are not on Google fibre. They put 32 customers per fibre. And give them all 1gigabit each.

Lorenceo

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#1567377 7-Jun-2016 19:11

Yes. It would.

No. It doesn't.

They're delivered over GPON.

Keep in mind if you want guaranteed bandwidth you're going to have to pay for it. Also keep in mind that overselling bandwidth is the way ISPs make money. The LFC's are no different. There are points of contention all along the way your traffic takes out to the internet.

Also the GPON split varies depending on the area. 32:1, 24:1, 16:1, etc. Pretty sure one of the Chorus reps on here said that in some rural areas there are GPON OLTs only serving two ONTs.

jnimmo

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#1567381 7-Jun-2016 19:14

Good question -

Basically only the CIR component of the connection is guaranteed (i.e. 2.5Mbps by default), so if 24 users were trying to fully utilise 200Mbps connections, they would only get to use their share of the available bandwidth, down to a minimum of 2.5Mpbs (or 0Mbps if the ISP isn't using VLAN tagging, correct me if I'm wrong)

DarkShadow

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#1567403 7-Jun-2016 19:29

jnimmo:

down to a minimum of 2.5Mpbs (or 0Mbps if the ISP isn't using VLAN tagging, correct me if I'm wrong)

Let's say you're on the 100Mbps plan.

If you're VLAN tagged, you get 2 pipes. One fixed sized pipe with 2.5Mbps speed, guaranteed; and one variable sized pipe with up to 100Mbps speed but no guaranteed minimum.

If you're VLAN untagged, you only get one variable sized pipe with with up to 100Mbps speed but no guaranteed minimum.

Talkiet

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#1567407 7-Jun-2016 19:32

As above, only CIR is guaranteed.

Cheers - N

Please note all comments are from my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.

UrbanNZ14

17 posts

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#1567417 7-Jun-2016 19:41

I had a quick look at the Ultra Fast Fibre UFB CIR wholesale prices, very expensive ! Okay so you're only guaranteed 2.5Mbps. And as @Aredwood said obviously not every user will be completely saturating their connection at the same time. If 1Gbps connections were to go national, would we start to see greater traffic contention.

Are there any plans at current to upgrade the OLTs to 10GPON 10Gbps. Here is a link from Huawei http://www.huawei.com/ilink/en/solutions/broader-smarter/HW_453305. This would provide quite a performance enhancement and remove the limitations of our current GPON architecture?

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Talkiet

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#1567421 7-Jun-2016 19:47

It's not so much "not every user will be completely saturating their connection at the same time".. .more like "it's rare for more than a couple of users on an OLT port to saturate their connection for more than a few seconds at a time."

Bear in mind that the majority of BB traffic at peak time is streaming media of some sort, and that only has to come in as fast as needed - not line rate. So you're talking (even on fibre) at between 2 and 9Mbps for the majority of streaming services. (Almost no-one streams UHD Netflix or 2k/4k youtube)

There's not many people mirroring alt.binaries.whatever...

Currently there's no real limitations of the current GPON architecture...

Cheers - N

Please note all comments are from my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.

richms

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#1567423 7-Jun-2016 19:50

You are assuming that it is a limitation. I dont see that gpon on a 16 way split will be a limitation unless all 16 connections were into somewhere like a student location where everyone was trying their hardest to download the internet at the same time every evening.

Until we see a national rollout of 1 gig plans, most people opting for them instead of the cheap nasty low speed plans, and then perhaps see some congestion then its a non issue. It not like the Krapi Cable Congestion thread on a national scale.

Richard rich.ms

sbiddle

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#1567442 7-Jun-2016 20:09

Firstly it will be a long, long, long time before all 16 splits are used. Even then the average throughput from users isn't going to get close to saturating that unless average users increases exponentially beyond what it is now (which is 100Gbps per month based on Chorus stats)

Aredwood

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#1567449 7-Jun-2016 20:18

Also it is already cheaper for an ISP to pay for a base speed fibre connection than it is for an ADSL connection. And that price gap will only get bigger. So eventually ISPs will start actively moving all of their customers to fibre. Even the really low usage ones who only check their email and don't do much else online. So a lot of the 16 connections per fibre will be taken by low users.

Sure it could be better. But it would cost a lot more. And most users won't see any difference. What we have got is actually really good value for money. And has been designed for future expansion.

DarkShadow

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#1567463 7-Jun-2016 20:44

UrbanNZ14:

Are there any plans at current to upgrade the OLTs to 10GPON 10Gbps. Here is a link from Huawei http://www.huawei.com/ilink/en/solutions/broader-smarter/HW_453305. This would provide quite a performance enhancement and remove the limitations of our current GPON architecture?

https://www.facebook.com/Chorusnz/photos/a.369670109741427.78171.232281130146993/976771322364633/?type=3&theater

darylblake

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#1567473 7-Jun-2016 21:05

I wouldn't concern myself with 16 - 24 homes or businesses saturating GPON.

You just wouldn't do it.

UrbanNZ14

17 posts

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#1567509 7-Jun-2016 21:50

Please don't get me wrong. I'm extremely proud of our countries accomplishment in regards to the Ultra Fast Broadband network. And it's such a luxury to have. I'm just a curious person hence all the questions and you all have provided me a greater insight into GPON, I've enjoyed reading all your replies. And the consensus I gather from the replies is the network is fine how it is for the foreseeable future.

The Chorus Facebook post was an interesting read! Will definitely keep an eye on NG-PON2 technology.

I suppose the next step is IPTV -although Vodafone currently offers this service on UFB in select locations using multicast?

BarTender

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#1567515 7-Jun-2016 21:58

Vodafone use multicast to broadcast their content across the GPON. Then it just depends on how much capacity they want to multicast vs per subscriber unicast over the regular bitstream 2a service.

Plenty of folks know how it works. And after the last few weeks of work the GPON isn't of the greatest concern. It's a whole myriad of other issues that hang around it that concern me a whole lot more.

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