remember the days of datastream?

isp's could have a wicked 2:1 contention ratio and still be poor due to then users able to saturate the shared pipe so easy.

note we talking about gigabit per street rather than per node, a street could have several g.fast boxes.

Edited by Chrysalis (Tue 08-Sep-15 19:06:02)

Data stream behaviour passed me by....

Won't it be hard for one gigabit to support multiple g.fast nodes in a street? It'll either be 1Gbps P2P, or 2.5Gbps shared GPON, or 10 Gbps shared XGPON. There isn't really a 1Gbps option that works in a shared setup.

Perhaps this makes things clearer -

http://i.imgur.com/ExRoSp1.png

yeah I think it will be 2.5gbps, with possible upgrades in busy areas.

When Openreach were commissioning the cab I'm connected to I'm pretty sure there was a bundle of 4 fibres coming into the right hand side of the cab.

In reply to a post by Chrysalis:

doesnt a single gigabit per street seem a bit low for when a single user can pull 300mbit/sec?

Nope. The rule II have historically seen is that a single customer should not be able to use half the maximum bandwidth.

The Datastream issues came from selling 2Mb on 2Mb, perhaps 3Mb, PVCs

Bandwidth usage rises by a fraction of maximum speed increase when a customer is migrating from a fast SFBB service to another service. Usually doubling the speed of the ultrafast increased usage by 30-40%. This increase further drops as the speeds go higher. 300Mb top speed on GigE would be just fine for nodes of these sizes. 16 connections at 300Mb each contends a gonet 4.8:1 and requires 3 people on the node at an one time pulling down data at full speed to leave 100Mb for the other 13, which will probably be fine as it's extremely unlikely for 3 people of 16 to be downloading at 300Mb simultaneously.

Average usage on heavy broadband ISPs is about 1Mbps per customer at peak period. A 16 person node delivers 60Mbps for each customer.

There are ISPs selling 300Mb on 600Mb, 500Mb on 800Mb. This on full cable nodes.

VM selling 300 on 800 is fine as long as the node sizes are appropriate, hundreds passed per node. BT selling 300 on 1Gb to a handful of customer's is fine.

so your example is gigabit per node not per street?

We will wait and see as to what happens as I think heavy users tend to congregate in certain areas such as student areas for example.

In reply to a post by Ignitionnet:

VM selling 300 on 800 is fine as long as the node sizes are appropriate, hundreds passed per node.

That's perfectly reasonable when you look at averages - especially at 1 Mbps per user.

It's still a bit worrying that only 3 users - out of hundreds - can saturate things.

Buy that man a pint!

In reply to a post by WWWombat:

due to the fact it has a C-WDM splitter pre-installed unless it was one of the original 2010 cabs then you are SOL.

Didn't know that. Are they retro-fittable?

<SNIP>

I assume your FTTC figures really relate to unvectored capability. With vectoring, you'd likely get 100Mbps to 400m. Even without vectoring, you can get 80Mbps at 400m initially ... but the dreaded crosstalk will eat away at that.

In my area 100,000 properties 30-40% would get >200 Mbps. Maybe ish.

The Sagentia report gives a nice breakdown of line lengths:
http://postimg.org/image/bp372fcnn/

<snip>

all that is required is a new line card.

A new linecard where?

100% they have a C-WDM MUX (I mean MUX not splitter) except the older ones where there isn't enough room to add a MUX or an additional modem so they need a baby cab. However, baby cab is not a big issue apparently. Due to the size of the estate we are talking I doubt that will be a big issue too.

Line lengths. Interesting. I had to adjust my figures a bit because they didn't fit with some other data. All a bit rough.

New line card? Existing cards are 2.5Gbps new cards are dual 2.5Gbps/10Gbps so for G.FAST the plan is to use the 10Gbps overlay. As mentioned elsewhere BT are testing 1Gbps. I bet that is because the vendor doesn't have an IC capable of doing it within the power envelope - would be my guess.

In reply to a post by Chrysalis:

so your example is gigabit per node not per street?

We will wait and see as to what happens as I think heavy users tend to congregate in certain areas such as student areas for example.

Yes. The backhaul BT are testing is point to point not a PON.

Heavy usage on cable in student areas is largely an upstream problem though, obviously, those guys take their toll to an extent on the downstream. Downstream is a different matter for obvious reasons; you can saturate upstream just by leaving a torrent client seeding, to saturate a big downstream you're either running MJ-12 or are one of those weird digital hermits who feels the need to try and mirror the contents of binary usenet groups onto their home storage.

As with FTTC Openreach aren't guaranteeing maximum performance, G.fast has a prioritised rate of 80Mb in the trials compared with 30Mb on production 80Mb FTTC.

A gigabit per node is fine.

Edited by deleted (Wed 09-Sep-15 08:23:58)