Interesting that’s going to cause issues with BT/EE and there 700 min guarantee

So that begs a question is there are priority as to who gets what bandwidth at the pole?

If you connected at 1000/115 compared to 150/30

If it’s contended at the pole

Why pay for 1000/115 if you cannot use it all the time because it’s shared out of 2.4

In reply to a post by einsteinagogo:

Interesting that’s going to cause issues with BT/EE and there 700 min guarantee

It isn't. The likelihood of that being congested is very low. If you do get less and complain you will be free to leave.

So that begs a question is there are priority as to who gets what bandwidth at the pole?

Nope.

Why pay for 1000/115 if you cannot use it all the time because it’s shared out of 2.4

Residential broadband (and most business broadband) is a shared/contended service. As is the vast majority of the wider internet.

If you want a guaranteed 1000Mb then you are going to need to pay hundreds a month for a dedicated leased line.
That would only guarantee those speeds between you and your provider. The internet beyond your ISP comes with no such guarantees no matter how much money you want to throw at it.

People use the internet in bursts. Most people don't take the highest speed packages.
Bottlenecks on the Gpon section of the connection are extremely rare.
People wouldn't want to pay what it would cost to build the network in such a way that there's sufficient capacity/bandwidth for everyone to max out their connections at the same time.
It would be a silly waste of money to do so.

A provider can choose to offer as low or as high a guarantee as they want. It says nothing about the condition of their network.
They only need to demonstrate they can provide the headline rate (900Mb for example) on average at peak times.

Openreach provides different minimum rates for different contractual levels.

The rate you sign up for is known as the PIR (Permitted Information Rate); the guaranteed rate is the CIR (Committed Information Rate). So, for example, the BT 900/110 product maps on to the Openreach 1000/115 product, which has a PIR of 1 Gbps and a CIR of 110 Mbps. The OR 120/20 product has a PIR of 120 Mbps and a CIR of 55 Mbps.

Note that the CIR doesn't change with every PIR - most OR products above 160 Mbps PIR have a CIR of 110 Mbps.

However, with FTTP you are never "connected at 1000/115 compared to 150/30" as you put it. The connection between your ONT and the ISPs OLT is always 2.48 Gbps downstream and 1.2 Gbps upstream. The throughput limitation happens inside the network switches using a technique called traffic policing.

A bit of a simplification, but the process works roughly as follows:
- each of the your packets has a tag associated with it which indicates whether it can be discarded by a switch
- if you start to exceed your CIR (your guaranteed rate) your packets get tagged as "eligible for discard"
- if there is still spare capacity on your PON (no-one else needs it at that point), then they won't be dropped, and you'll get throughput above your CIR
- if capacity is starting to be limited (others are also busy) then some of your packets are likely to be dropped - if others are also exceeding their CIR, then their packets will also be dropped, and everyone will see reduced throughput
- if you were to start to exceed your PIR (what you've paid for) then your packets will be dropped

Very helpful

Is there a technical Openreach document which explains the technical details of Broadband in the UK?

Openreach publish their Suppliers Information Notes (SINs) here: https://www.openreach.co.uk/cpportal/help/suppliers-...

Other networks use faster fibre options, XG-PON, and XGSPON for example. Openreach so far have not (apparently) deployed this. Non-openreach networks include wholesale CityFibre (and apparently nexfibre) as well as ISP-specific operators such as Toob, and Zzooom.

In reply to a post by einsteinagogo:

Why pay for 1000/115 if you cannot use it all the time because it’s shared out of 2.4

Because 99.9% of the time you can, and in the other 0.1% you won't notice anyway.

There are a mixture of people on your street sharing the PON, from hardcore gamers to OAPs who do nothing more than download E-mails.

Even the hardcore gamers aren't downloading games all the time - they have to spend time playing those games too.

Beyond a certain point, giving people higher download speeds doesn't increase the amount of data they download. They just do it in a shorter time, which means you are less likely to be using the network at the same time as them. That's why EE aren't worried about selling 1.2G and 1.6G services on a shared 2.4G GPON.

*Average* usage of a home Internet user is about 500GB per month(*), which if you spread it out is only 1.6Mbps. Obviously it goes up and down over a 24 hour period, but even in the "peak hour" it's only likely to be 5-10Mbps.

(*) OFCOM 2023 report, figure for 2022 I think.

In reply to a post by potterer:

Openreach provides different minimum rates for different contractual levels.

The rate you sign up for is known as the PIR (Permitted Information Rate); the guaranteed rate is the CIR (Committed Information Rate). So, for example, the BT 900/110 product maps on to the Openreach 1000/115 product, which has a PIR of 1 Gbps and a CIR of 110 Mbps. The OR 120/20 product has a PIR of 120 Mbps and a CIR of 55 Mbps.

PIR is Peak Information Rate not permitted.
There is another value used in the industry which is EIR - Excess Information Rate, which is essentially PIR-CIR.

CIR that Openreach quote in their product spec and SINs is NOT actually a CIR. CIR should be a guaranteed rate, however in Openreach's case it is a statistical marketing value that they hope you will be able to achieve most of the time.

On PON networks when you configure a CIR that value is reserved bandwidth on the PON which you are guaranteed to get. Openreach use 1:32 split, so if you assume they use a max of 30 ports they could have 3.3G of CIR, they only have 2.48G as they use GPON, so it cannot be configured as a CIR on their network.

Prioritisation on PON is done via T-CONs and GEMs but works much as potterer says for switches.

Hi,

In reply to a post by Ad_G:

In reply to a post by potterer:

Openreach provides different minimum rates for different contractual levels.

The rate you sign up for is known as the PIR (Permitted Information Rate); the guaranteed rate is the CIR (Committed Information Rate). So, for example, the BT 900/110 product maps on to the Openreach 1000/115 product, which has a PIR of 1 Gbps and a CIR of 110 Mbps. The OR 120/20 product has a PIR of 120 Mbps and a CIR of 55 Mbps.

PIR is Peak Information Rate not permitted.
There is another value used in the industry which is EIR - Excess Information Rate, which is essentially PIR-CIR.

CIR that Openreach quote in their product spec and SINs is NOT actually a CIR. CIR should be a guaranteed rate, however in Openreach's case it is a statistical marketing value that they hope you will be able to achieve most of the time.

On PON networks when you configure a CIR that value is reserved bandwidth on the PON which you are guaranteed to get. Openreach use 1:32 split, so if you assume they use a max of 30 ports they could have 3.3G of CIR, they only have 2.48G as they use GPON, so it cannot be configured as a CIR on their network.

Prioritisation on PON is done via T-CONs and GEMs but works much as potterer says for switches.

Note that you are assuming that it is actually a 1:32 split and that everyone on the PON has ordered a >=160M service.

The reality is that
a) most PONs will not be fully occupied (and Openreach only design to a maximum of 1:30 split, the extra 2 are for contingency)
b) most people ordering FTTP will not order the higher tiers so they probably can commit to the "Prioritised Downstream" rate even if the whole PON is occupied.

I understand that Openreach will consider splitting PONs where they can't guarantee the "Prioritised Downstream" rate.

Those on XGS-PON shouldn't feel smug:
- they may have a higher headline data rate but
- the split could well be 1:128 which gives a slightly worse full rate split than 1:32 on PON but
- they do benefit from better statistical spreading of traffic but
- that is offset to some extent by offering high headline rates (e.g. > 1G) which could allow a few users to use large amounts of bandwidth and saturate the PON.