Assurance rates

I was informed by one ISP that an assured speed was applied by Openreach. The assured speed quoted was 15 Mbps and that in order for it to be classed as an 'official' fault, it would need to be under this constantly for a 4 hour period.

I have not come across this anywhere and wondered whether anyone else had?

One other query would this also apply to say Talk talk wholesale (or other backhaul provider) who I kinda thought had their own back haul and would not be affected by this?

Regards
Mac

The assured rate only covers the fibre between the cabinet and the handover node, and this is referring to throughput rather than sync speeds

i.e. if your line syncs under 15 Mbps their is not guarantee that will bring it into the 15 Mbps region

Hi Andrew,

Apologies for being thick ....

For example if a cabinet is some 80m from the cabinet and syncs at 78 ... what would that mean for the end user in the context of the assurance rate?

And what would the Openreach assurance rate mean for some one who was on TTW back haul?

Regards
Mac

In reply to a post by Mac99:

For example if a cabinet is some 80m from the cabinet and syncs at 78 ...

Please can you fix whatever is wrong there, as it's beyond me what you meant.

If it helps anyway, on FTTC the connection speed a user gets on FTTC depends on their cabling distance from the FTTC cabinet, (via the phone cabinet), and the quality of that cabling. In the same way as on ADSLx it depends on the user's cabling distance and quality from the exchange.

We then have the assured rate I think MrSaffron is referring to, which is to do with the throughput capability of 15Mbps per customer between the cabinet and the exchange. This is of course affected by customers so far from the exchange that they connect below 15Mbps. There are many. Each of these increases the total availability for those that connect above 15Mbps.

On top of that, this applies to the amount of traffic each connection is generating/requiring at any given moment in time. It's a real-time system.

Until the connection reaches the exchange it is all Openreach and ISP-agnostic. Once it gets to the exchange and is handed over to the ISP then it becomes completely the ISP's problem to provide sufficient backhaul from that and all exchanges it services, and the ongoing links from its own routers to the worldwide web to carry the total of all of them. Nothing at all to do with Openreach or its guarantees.

Which is why some ISPs slow down hugely at busy times. (TalkTalk, BT, maybe Sky?) and some don't (AAISP, Uno, mostly Zen and IDNet). Then there are a hundred or so small ISPs that we hear little about. No doubt their "busy" performance varies hugely as well.

Ooh. This is complicated.

There are 3 separate things you might mean:

Openreach have descriptions of their GEA-FTTC service, but use the term "Downstream Prioritisation Rate". According to SIN 498, this can be set to a value of either 15Mbps or 30Mbps, depending on package chosen. This is obviously reduced to the line rate if that is lower.

BT Wholesale use the term "assured rate" for something completely different, in their WBC portfolio. I'm assuming you aren't really referring to this.

BT Wholesale set a "minimum best-efforts speed" for their FTTC packages:
- Standard 40Mbps packages get 20Mbps min
- Elevated 40Mbps packages get 30Mbps min
- Standard 80Mbps packages get 40Mbps min
- Elevated 80Mbps packages get 60Mbps min
(The handbook predates the introduction of 55Mbps, so I have no idea there)

In reply to a post by Mac99:

For example if a cabinet is some 80m from the cabinet and syncs at 78 ... what would that mean for the end user in the context of the assurance rate?

As others have mentioned, the Openreach "prioritisation rate" applies between cabinet and exchange.

This "prioritisation rate" comes into play when too many subscribers (on the one cabinet) are trying to download simultaneously, and congestion is felt in the fibre(s) running to the cabinet.

In these circumstances, the OLT (in the exchange) attempts to balance usage between lines on the cabinet, subject to the differing "prioritisation rates" that the lines have.

If the OLT has to drop some of your traffic as part of this balancing act, it uses some QoS markings to help decide what should go.

In your example, your "up to 80Mbps" line running at 78Mbps would get a prioritisation rate of 30Mbps.

Congestion in the backhaul, be it TTB, BTW or whoever, is down to the backhaul provider and (likely) the amount ordered by the ISP. It seems that BTW set their limits to something higher than Openreach.

Edited by deleted (Sat 14-Jan-17 03:40:35)

Nods head and that response saves me typing...

Hi all,

Thank you very much for the replies.

A big thank you to Robert for the excellent information which even I can understand.

Thanks Wombat for the extra information in terms of minimums.

Thanks again.
Mac

Edited by deleted (Sat 14-Jan-17 16:30:51)