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Broadband Related => FTTC and FTTP Issues => Topic started by: Geekofbroadband on October 28, 2021, 07:51:13 PM

Title: Openreach FTTP Technical Questions
Post by: Geekofbroadband on October 28, 2021, 07:51:13 PM
Hi, so I have some questions about FTTP from Openreach.

1) I noticed on BT's website it says "Your Stay Fast Guarantee 450Mb" which makes me think the speed will be inconsistent, but it being true FTTP, shouldnt you always get or very close to the speed you pay for, as there's none of the downsides of FTTC like crosstalk, line length, etc..

2) Does anyone know how much bandwidth there is for each FTTP splitter to share between peoples houses, how many people one splitter serves, and how many people would it take to saturate all the available bandwidth shared to a splitter for it to start effecting everyone on it?

3) What is the reason BT advertise 900Mbs instead of 1Gig? I understand they can't offer symmetrical speeds like smaller FTTP companies do because they have to serve a lot more people, but it seems like a missed opportunity to sell "1Gig" and match Virgin.

Thanks.
Title: Re: Openreach FTTP Technical Questions
Post by: dee.jay on October 28, 2021, 08:25:12 PM
1) You are confusing line speed with the speed of the network. I think this covers BT's arse because if you can't download at more than 450Mbps - then you can't really complain. The problem is that when you consider 1,000 households all downloading at 80Mbps (I'm picking numbers for the sake of maths) then that's 80,000Mbps of backhaul you have to find in order to supply that speed everywhere. Turn that up to 900Mbps fibre, then all of a sudden the backhaul has to be vastly quicker. There are different kinds of bottlenecks that are turned up when you start increasing the speed.

2) I don't know exactly, but I think there's a 2.4Gbps limit somewhere between X number houses?

3) Not sure - probably the same reason as why it's 80Mbps not 100Mbps when VDSL2 is probably technically capable of it - just what BT worked out they could reliably offer I suppose.
Title: Re: Openreach FTTP Technical Questions
Post by: Alex Atkin UK on October 28, 2021, 10:22:35 PM
1) I noticed on BT's website it says "Your Stay Fast Guarantee 450Mb" which makes me think the speed will be inconsistent, but it being true FTTP, shouldnt you always get or very close to the speed you pay for, as there's none of the downsides of FTTC like crosstalk, line length, etc..

Its down to contention on the PON, see point 2 below.

2) Does anyone know how much bandwidth there is for each FTTP splitter to share between peoples houses, how many people one splitter serves, and how many people would it take to saturate all the available bandwidth shared to a splitter for it to start effecting everyone on it?

Its 2.4Gbit per PON which can have up to 30 properties sharing it.  (technically 32 but Openreach keep two spare)
I assume if a lot of customers sign up for 900Mbit on the same PON, they would have to consider upgrading to XGPON which has more bandwidth and putting the top users on that, if they start to drop below 450Mbit.  But as not everyone will max out their connection at the same time, they're betting on that not happening very often or any time soon.

Its not like any other residential network can sustain every user maxing out their connection at the same time either, FTTC, Cable, FTTP, are all contended mediums - as in the theoretical maximum speed of the customers connected combined is many times more than it actually can handle.  But the odds of everyone maxing out at the same time is slim to none.  Even at the ISP their peers to the Internet wont be able to sustain every single customer maxing out at the same time, and this is why different budget ISPs have different performance sometimes, a more expensive ISP will be more careful to have overhead compared to their "average" measured usage of their users.

The only way to have guaranteed capacity is to pay thousands for a leased line, where the ISP will make sure you get priority.

3) What is the reason BT advertise 900Mbs instead of 1Gig? I understand they can't offer symmetrical speeds like smaller FTTP companies do because they have to serve a lot more people, but it seems like a missed opportunity to sell "1Gig" and match Virgin.

Almost certainly OFCOM rules, they have to advertise what the expected throughput would be for the end user and that generally will max out at 940Mbit (as that's about the best you get from a Gigabit ethernet port), potentially less due to overheads, so 900Mbit is a safe bet.
Title: Re: Openreach FTTP Technical Questions
Post by: Geekofbroadband on October 29, 2021, 01:01:18 AM
I see thanks for the answers. This had led me to ask more questions  ;D

1) I'm assuming the fibre modem openreach give you doesn't have any 2.5GB ports meaning if they did ever decide to sell above 900Mbs they would have to replace both the modem and router for people (I think the Smart Hub 3 is going to have at least 1 2.5GB port), unless they ever offered an all in one fibre modem/router the same way they did for FTTC(Do FTTP all in one modem/routers even exist?)

2) So theres 2.4Gbit shared between 30 houses with OR FTTP, in comparison to Virgin Media for exmaple, do you know how much bandwidth they have to share between each cabinet to houses? Although I guess this is different between DOCSIS 3 and 3.1 with 3.1 adding more channels which helps congested areas.
Title: Re: Openreach FTTP Technical Questions
Post by: dee.jay on October 29, 2021, 10:01:00 AM
1) Well not sure what to comment on this - as it is we're heading towards 900Mbps via FTTP - who knows what the "next step" will be after that - if there are indeed 2.4Gbps PON limits, then almost certainly this would need to be upgraded at some point to accommodate. At least once everyone has FTTP then that's the hard part completed - fibre optic speeds can run to hundreds of Gbps.

2) I think DOCSIS works differently, it's like a big shared LAN where many more houses could be contending for access to the medium (i.e. the cable) - but I don't know the exact numbers.
Title: Re: Openreach FTTP Technical Questions
Post by: j0hn on October 29, 2021, 10:27:50 AM
Hi, so I have some questions about FTTP from Openreach.

1) I noticed on BT's website it says "Your Stay Fast Guarantee 450Mb" which makes me think the speed will be inconsistent, but it being true FTTP, shouldnt you always get or very close to the speed you pay for, as there's none of the downsides of FTTC like crosstalk, line length, etc..

No.
BT's 450Mb/s guarantee on the 1000/115 tier is the highest guarantee any OpenReach based ISP provide on that tier.

OpenReach only guarantee 110Mb/s to the ISP.

It's PON, it's a shared, contended technology. It's home broadband, it's contended.
As alex says it's 2.4Gb/s down and 1.2Gb/s up shared between up to 32 homes (with up to 4 services per home) on each PON

OpenReach won't upgrade it if you get contention either.
BT would have to pay you compensation for not buying the minimum. Eventually they would release you from your contract.

The cablelinks are just as highly contended, sharing traffic with lots of other FTTP customers on your exchange (not just for PON).

If you want higher than 450Mb/s guaranteed then you need a leased line.

Virgin are only allowed to sell there's as 1gig because they actually provision at over 1100Mb/s meaning it's above a gig after overheads.
Title: Re: Openreach FTTP Technical Questions
Post by: Weaver on October 29, 2021, 11:27:27 AM
Iím wondering if the advertising regulators have decided that say 1 gig means 1 Gbps of IP SDUs (payload) or even of TCP SDUs (TCP payload) so the overhead of headers has to first be subtracted making the advertised figure lower if thatís the way itís being done. A 60 byte IPv6+TCP header out of 1500 bytes is, what, 4 %. More if TCP timestamps are added.

It annoys me when people talk about ďthe speedĒ without saying speed of what. Not accounting for DSL overheads is a big deal too.

I presume typical ISPsí FTTP services will also have overhead from outer, L2, protocols, but Iím assuming these are pre-discounted or whatever the right term is; their overhead always pre-subtracted. Or not. Iím thinking of ethernet framing headers, or PPP+PPPoE too.
Title: Re: Openreach FTTP Technical Questions
Post by: dee.jay on October 29, 2021, 11:29:19 AM
If you want higher than 450Mb/s guaranteed then you need a leased line.

And just to point out, these services are *extremely* expensive for ordinary consumers.

For example, 100Mb/s leased line from AAISP: -

TalkTalk EAD and Internet access 100Mb/s

Install
£2775
£935.61 Monthly

Title: Re: Openreach FTTP Technical Questions
Post by: Weaver on October 29, 2021, 11:45:11 AM
Thatís good, Iíve never seen any A & A prices. How much for 1 Gbps symmetrical ?
Title: Re: Openreach FTTP Technical Questions
Post by: dee.jay on October 29, 2021, 12:00:18 PM
100Mb/s is as fast as they quote on the website.

They do say they offer more - but one would have to speak to the sales team to find out the prices.

"Our Ethernet services provide high speed, high reliability, links to the internet and between sites with a coverage of approximately 90% of UK business addresses. Typically customers will buy 10Mb/s symmetric (both ways at once) connected via 100Mb/s fibre to allow quick upgrade to faster speeds when needed. Because we use real fibre-optic links, we are able to offer speeds of up to 10Gb/s if required."

I know at work we have 2 x 1Gbps RO2 (fully redundant) BT Business circuits, they are £1500 a month.
Title: Re: Openreach FTTP Technical Questions
Post by: Reformed on October 29, 2021, 01:58:52 PM
The advertising is based around the goodput, what people would see on speed tests, that 50% of customers will achieve at peak load times. Nothing more interesting than that.

Congestion on a port is unlikely for now, contention is far higher deeper into the network.

The 900 advertised is what the operator expects you to achieve at peak times. The 450 is a minimum.

Again the 900 is not a maximum, it is the expected performance at any point during the day.

A far bigger bottleneck is that most of the Internet can't max out a gigabit link.
Title: Re: Openreach FTTP Technical Questions
Post by: Reformed on October 29, 2021, 02:00:27 PM
£935.61 Monthly

That is really expensive.
Title: Re: Openreach FTTP Technical Questions
Post by: g3uiss on October 29, 2021, 02:07:40 PM
Quite cheap compared to what leased lines used to cost !
Title: Re: Openreach FTTP Technical Questions
Post by: Reformed on October 29, 2021, 02:35:29 PM
So are a lot of things which is why we don't judge today's pricing on tech based on what it used to be.
Title: Re: Openreach FTTP Technical Questions
Post by: Alex Atkin UK on October 29, 2021, 02:59:27 PM
That is really expensive.

Remember you're probably paying for a service level agreement, priority traffic on their network so you consistently get full speed and quick response with compensation if anything breaks.

Anything other than leased lines is a best-effort service with no guarantees.  BT may promise a minimum speed, but I doubt they will do anything other than maybe a small refund on the price if they are unable to meet it.
Title: Re: Openreach FTTP Technical Questions
Post by: Weaver on October 29, 2021, 03:00:26 PM
Iíve been paying between £150-£200 pm for 7-11Mbps downstream, ~1 Mbps upstream. (Mind you, there were extras in that, such as traffic priority and things like email services, domain name hosting and registration x lots, that pushed it up a bit.)

If someone wants a guaranteed 900 Mbps d/s, then getting two FTTP links and binding them would be a lot cheaper than a leased line and you would get a guarded min 2 * 450 Mbps d/s. Mind you, you would also need to upgrade your whole lan, router, switch, ethernet cables to be able to cope with 2 * 900 Mbps, so 2.5 G ethernet would be a minimum, albeit not very future proof, and you would possibly be well advised to get all your LAN up to 10 Gbps ethernet plus an appropriate switch+router. Starts to become a serious up-front cost, and your hosts might not be able to cope with 2.5 Gbps or 10 Gbps, never mind the limitations of wi-fi.
Title: Re: Openreach FTTP Technical Questions
Post by: GigabitEthernet on October 29, 2021, 03:09:00 PM
£200 PCM on a broadband connection? Heavens above, I pay £20
Title: Re: Openreach FTTP Technical Questions
Post by: Ixel on October 29, 2021, 03:49:23 PM
I'm paying about £150 per month for my FTTP connection (including /29 IPv4) with Cerberus at the moment. Yeah, I know they have reduced their pricing considerably (recently) but that means committing to a new 12 month contract which I don't have the option of really doing due to switching to a local altnet ISP soon. I wouldn't even be aware of the reduced pricing if I didn't check the website for myself.

I remember when I had bonded FTTC with AAISP, it was a little costly but at the same time it was a lot cheaper than paying for a leased line. That was some time before the initially revised FTTPoD pricing became available.
Title: Re: Openreach FTTP Technical Questions
Post by: GigabitEthernet on October 29, 2021, 04:10:31 PM
Okay £150 for FTTP that's presumably many 100s of megabits I get but for 11Mbps it seems insane
Title: Re: Openreach FTTP Technical Questions
Post by: Weaver on October 29, 2021, 04:16:16 PM
@Gigabitethernet - thatís the downside of living in the middle of nowhere. >7 km copper lines * 3 bonded together. Need triple speed from the three bonded lines to make life bearable and am completely happy with the ultra reliable result. Backed by 3G auto failover if all three lines should go down simultaneously, the link never ever goes down. If one line fails, then the traffic is just diverted to the other lines. I did have four lines, but one died completely and couldnít be fixed, so I ordered a new line instead, and to cut a long story short, I ended up with three lines not four, but at the moment the three do what I need.

I included the cost of line rental in that figure.
Title: Re: Openreach FTTP Technical Questions
Post by: dee.jay on October 29, 2021, 04:20:50 PM
I would happily pay £150 for FTTP at this point.

Currently paying £55+£43 a month for 2 x line rentals and 2 x FTTC circuits giving me about 120Mbps, and they're slowing down as the years pass thanks to crosstalk. Luckily both of my lines has been pretty reliable - have had FTTC on one line since 2012 - and I think I've had to call Sky twice about an outage in all that time. Went to two lines at the end of 2018, and now there's two of us working from home I am pretty glad to have two.

The £900+ a month for a leased line is not for me - it's not for 99% of folks around here - if you were running your business from home and absolutely had to have backup of SLA's and such then it could make sense.



Title: Re: Openreach FTTP Technical Questions
Post by: Weaver on October 29, 2021, 04:32:57 PM
Iím not sure who even needs SLAs for such services now, since most of us have 4G or even 5G, which could tide your over in an outage and thatís the way to get reliability. Mind you, around here if thereís a lightning strike and a power outage, then the 4G basestation just goes down anyway, which is appalling. I wonder if it has no UPS/generator - could that even be possible? Or is it just freaked out and needs better protection ?

I have instant switchover to 3G; lots of routers have this feature.
Title: Re: Openreach FTTP Technical Questions
Post by: Alex Atkin UK on October 29, 2021, 05:50:54 PM
Iím not sure who even needs SLAs for such services now, since most of us have 4G or even 5G, which could tide your over in an outage and thatís the way to get reliability. Mind you, around here if thereís a lightning strike and a power outage, then the 4G basestation just goes down anyway, which is appalling. I wonder if it has no UPS/generator - could that even be possible? Or is it just freaked out and needs better protection ?

I have instant switchover to 3G; lots of routers have this feature.

If you're a business, I'd imagine mobile failover is better than nothing but would still hobble business to some degree, especially if you have remote access of some kind and wont necessarily have a static IP on the backup.  I'd wager your configuration is a lot more robust than 9/10 businesses.
Title: Re: Openreach FTTP Technical Questions
Post by: g3uiss on October 29, 2021, 06:05:10 PM
Alex you couldnít be more spot on. One of the charityís Iím involved with is 100% dependent on connection for absolutely everything from finance to selling tickets. They have one FTtC connection and when challenged about redundancy said it was unnecessary expense ! And they arenít the only ones I know of.
Title: Re: Openreach FTTP Technical Questions
Post by: Ixel on October 29, 2021, 06:13:18 PM
I would happily pay £150 for FTTP at this point.

I agree. If I didn't have the options I do now then I'd still go for it at that price, after all I'm still content with paying this price until I'm able to switch to the local option in the near future. :D

That said, there's a limit and £900+/mo for a leased line is just way too much both for my wallet and my interests and needs.
Title: Re: Openreach FTTP Technical Questions
Post by: burakkucat on October 29, 2021, 06:20:13 PM
That said, there's a limit and £900+/mo for a leased line is just way too much . . .

The leased line cost is just that - the rental cost of the infrastructure. Then there will be the cost of the service that one requires to be added on . . .  :swoon:
Title: Re: Openreach FTTP Technical Questions
Post by: dee.jay on October 29, 2021, 11:40:10 PM
I agree. If I didn't have the options I do now then I'd still go for it at that price, after all I'm still content with paying this price until I'm able to switch to the local option in the near future. :D

That said, there's a limit and £900+/mo for a leased line is just way too much both for my wallet and my interests and needs.

£900/mo for 100Mbps at that!
Title: Re: Openreach FTTP Technical Questions
Post by: Weaver on October 30, 2021, 04:21:33 AM
Iíd love to know what 1 Gbps and 10 Gbps cost.
Title: Re: Openreach FTTP Technical Questions
Post by: Bowdon on October 30, 2021, 10:41:09 AM
With these high speed connections I'm wondering what is the highest transfer rate during normal Internet use?

What services allow you to transfer at a very high speed? I'm sure during normal web browsing and emailing we won't feel any effect.

But does Steam allow for a 1Gbps connection to max out or is it capped?

I can't imagine video on demand needs a 1Gbps connection.

I transfer files regularly so I can see how a specific business dealing in file transfers might have a very high speed cap. But I bet there isn't many other places.
Title: Re: Openreach FTTP Technical Questions
Post by: Ixel on October 30, 2021, 11:05:55 AM
What services allow you to transfer at a very high speed? I'm sure during normal web browsing and emailing we won't feel any effect.

Usenet or other P2P can. Off-site backup assuming the route the connection takes as well as the server is capable of handling such throughput. A 'maximum quality' 4K 'gamestream' (NVIDIA) might be around 100Mbps with rapidly changing content perhaps, assuming high frame rate too, but certainly won't max out a gigabit connection. Web browsing (not a large file transfer) and emailing won't really notice it.

But does Steam allow for a 1Gbps connection to max out or is it capped

I guess it depends how much load the content server you're connected to is under, as well as the route your connection takes and how congested that might be. There's also the disk drive capabilities to consider and perhaps even the CPU (for decompressing the downloaded content?). However, assuming you're writing to a decent NVMe drive with a fairly decent CPU then it's possible Steam could max it out, if none of your hardware and the network connection has any bottlenecks.

Doing a download of CSGO a moment ago, I saw Steam peak at about 85MB/sec (nearly 700 megabits) but I also have some QoS rules setup which manage throughput of 'large transfers' at a lower priority and capped to 720~ megabits. This is with the Steam library on an NVMe RAID-0 array and CPU being a mildly overclocked AMD Threadripper 3990X (64-core).

(https://i.imgur.com/fBMK5YF.png)

I can't imagine video on demand needs a 1Gbps connection.

Definitely not haha, unless perhaps you're the server? :D
Title: Re: Openreach FTTP Technical Questions
Post by: Alex Atkin UK on October 31, 2021, 02:45:17 AM
What frustrated me is I just spent hours downloading an update for Microsoft Flight Simulator as it wouldn't go over 200Mbit.  I've seen Steam do 700Mbit also on Three 5G.  Usenet tends to do 500Mbit but I've seen reports of it going well over Gigabit with the right providers (I know one of my accounts has a 300Mbit cap).

I honestly never expected 5G to reach the speeds it has, I'm guessing the tower is usually not very stressed as people aren't aware its available or are just using it to watch YouTube on their phones.

The benefit of Gigabit in a multi-person household though is mostly down to the fact it IS hard to max out.  Ideally you'd always want your connection to be faster than you can use, so nobody ever noticed service problems, especially if anyone is gaming.

Interestingly my VPS is supposed to be provisioned on Gigabit but I'm lucky if it can do half that over Three 5G.
Title: Re: Openreach FTTP Technical Questions
Post by: Ixel on October 31, 2021, 01:54:01 PM
What frustrated me is I just spent hours downloading an update for Microsoft Flight Simulator as it wouldn't go over 200Mbit.  I've seen Steam do 700Mbit also on Three 5G.  Usenet tends to do 500Mbit but I've seen reports of it going well over Gigabit with the right providers (I know one of my accounts has a 300Mbit cap).

Ouch. At some point I need to check out that game. From what I've seen it looks highly impressive and realistic. Yeah with Usenet it will depend a bit on which provider(s) you use as well as the plan that you have with them. I think I use three different providers myself, ensuring they don't share the same backbone or w/e. One is unlimited access subscription while the others are purely failovers so they have prepaid data usage.

The benefit of Gigabit in a multi-person household though is mostly down to the fact it IS hard to max out.  Ideally you'd always want your connection to be faster than you can use, so nobody ever noticed service problems, especially if anyone is gaming.

Yeah definitely. That said, I still have some fairly basic QoS rules to ensure something or someone can't abuse the heck out of the connection to the point it disrupts everything or everyone else here. Prioritisation is mostly based on packet size, ACK's or DNS queries. Works well for me.

Interestingly my VPS is supposed to be provisioned on Gigabit but I'm lucky if it can do half that over Three 5G.

I take it that it's able to do gigabit generally at some other places? If so then I guess there's some similarity here with my connection and my dedicated server on OVH.

It struggles to do about 500 megabits generally from the dedicated server to my connection - can be lower than that at peak time. However, if I make it take a different route such as making a VPN connection when I recently tried out Voxility (using their internet access as 'premium' level on my server with them) then I generally get full gigabit from the dedicated server to my connection no matter what time of day from what I can see.
Title: Re: Openreach FTTP Technical Questions
Post by: Geekofbroadband on November 01, 2021, 10:06:26 PM
Are FTTP prices expected to drop further?

I saw these: https://www.express.co.uk/life-style/science-technology/1499231/BT-broadband-breakthrough-cheaper-prices-for-you

https://www.ispreview.co.uk/index.php/2021/09/rivals-sigh-as-ofcom-clear-openreach-fttp-broadband-price-cut.html

Not sure if that was the "Save £240 - Regional Offer" on the 500 and 900Mb BT packages or this is something seperate.
Title: Re: Openreach FTTP Technical Questions
Post by: Alex Atkin UK on November 01, 2021, 10:21:11 PM
It struggles to do about 500 megabits generally from the dedicated server to my connection - can be lower than that at peak time. However, if I make it take a different route such as making a VPN connection when I recently tried out Voxility (using their internet access as 'premium' level on my server with them) then I generally get full gigabit from the dedicated server to my connection no matter what time of day from what I can see.

Downloading a Thinkbroadband test file does 40-85MB/s, its extremely inconsistent.  That said, its on CentOS 7.9 with kernel 3.10 which does not support bbr congestion control.

I get the feeling they aren't offering quite the same service BHost were.  For one thing, my account was supposed to be unlimited bandwidth (which BHost listed as 2TB but presumably ignored overages, never hit it to see) but when Mythic Beasts took them over they took the 2TB literally it seems.

Considering a basic service from Mythic Beasts is WAY more expensive, I'm guessing they consider these legacy BHost accounts more of an annoyance.
Title: Re: Openreach FTTP Technical Questions
Post by: burakkucat on November 01, 2021, 11:33:31 PM
[off-topic]
That said, its on CentOS 7.9 with kernel 3.10 which does not support bbr congestion control.

You could use the recently released kernel-ml-5.15.0-1.el7.elrepo package set which certainly does have bbr congestion control . . .  ;)
[/off-topic]
Title: Re: Openreach FTTP Technical Questions
Post by: Alex Atkin UK on November 02, 2021, 05:27:03 AM
I think the problem is the kind of virtualisation they use the kernel has to match the hypervisor.

I'd move to something else but this is incredibly cheap for 2 Cores, 4GB RAM, 125GB storage, 2TB data for £8/month.  Their normal price for this would be £21.72/month.

Even a Raspberry Pi 3 server with only 1GB RAM and 100Mbit uplink is more expensive.
Title: Re: Openreach FTTP Technical Questions
Post by: j0hn on November 02, 2021, 10:58:00 AM
Are FTTP prices expected to drop further?

The OpenReach Equinox offer is a very small reduction in rental price for the provider. Don't expect it to have a big impact on consumer pricing unfortunately.

Quote
Not sure if that was the "Save £240 - Regional Offer" on the 500 and 900Mb BT packages or this is something seperate.

Nah that's been running since before the Equinox deal was signed off.