In reply to a post by camieabz:

Yep, good read, but at an exchange level, VOIP or gaming traffic is not going to be prioritised over other ISPs' heavy P2P customers, is it?

Well not unless BT are running something similar over the wholesale network. So if one is on an exchange with medium to high contention, what can the customer or ISP do? Convince all the other householders to move to the same ISP?

I wouldn't be surprised if they are.

I've never thought of it, and don't recall seeing it ever discussed, (are you the first to think of it? ), but the DLM design suggests the possibility.

In particular both the BTW DLM, (which still has relevance on FTTx and probably that extends beyond setting the IP Profile which we know it does), and the OR DLM, have specific facilities for ISPs to set priorities within customer, and therefore in effect for all customers of that ISP, at a few levels. I forget the details, as there are a number of priorities of which only three or four are implemented, but the aim is to tag VOIP/Gaming and such, then normal interactive, then the equivalent of Plusnet Bronze, within that customer's available bandwidth.

The OR one at least, maybe both, doesn't/don't let those ISP settings give any customer any advantage over another once it is in the OR, (or BTW?) systems. But it would seem logical that their systems could include detection of protocol and prioritise accordingly on a total traffic basis. The OR one specifically does apply the ISP tagging, but that's only until the handover at the exchange. IIRC the WBC one does so as well, throughout the backhaul.

Overall prioritisation would not be as finely tuned as the Plusnet one is, where specific third-party products are identified and classified. And the combination of the carried-through ISPs tags within a particular user's traffic with an overall protocol prioritisation would be extremely complex or even impossible given that it has to happen in realtime.

I'm not saying I think this happens, but I wouldn't rule out the possibility.

No idea. I'm on ADSL2+ as it happens, so I was thinking of us poor, hard-done-by rural folk.

I always assumed that contention became a distance from the exchange (tough luck mate) fight. There's a house for sale next door to my exchange, and I notice it every time I pass it in the car. I could walk 20 paces from its border and touch the exchange wall.

I can't justify moving house for ADSL, especially to my gf. Hehe!

There's also a slight chance that said house might not be as close to the exchange underground.

Edited by camieabz (Fri 21-Dec-12 21:32:04)

Even worse, (at the moment) - EO.

Presumably on an exchange line which I think at the moment means no prospect of FTTx!

I swear jelv, it's so close I'd dig the hole myself.

Well you've had plenty of practice .

Couldn't resist it, sorry. It's even (in a way) self-referential. Which makes it classic.

In reply to a post by RobertoS:

I've never thought of it, and don't recall seeing it ever discussed, (are you the first to think of it? ), but the DLM design suggests the possibility.

In particular both the BTW DLM, (which still has relevance on FTTx and probably that extends beyond setting the IP Profile which we know it does), and the OR DLM, have specific facilities for ISPs to set priorities within customer, and therefore in effect for all customers of that ISP, at a few levels. I forget the details, as there are a number of priorities of which only three or four are implemented, but the aim is to tag VOIP/Gaming and such, then normal interactive, then the equivalent of Plusnet Bronze, within that customer's available bandwidth.

Funnily enough, I was looking at this after the recent (re-)mention of turning off upstream QoS on the Huawei modem.

It turns out that the modem supports 8 level of QoS marking (using a scheme known as 802.1p), but only forwarding marking that is already present on the LAN.

Otherwise it seems that Openreach supports 4 of those levels (one level a "do not drop" level, the others all a "can drop" one). They also support an assured rate - but that really aims at focussed high quality video streams - I assume BT Vision may make use of this.

It'd be interesting to see if Plusnet's marking translates over, and convert to the Openreach mechanisms.

Likewide, it'd be interesting to see if anything on the local OS can generate QoS markings too, for upstream.