Downstream line rate

Sterlingtimes

My Talktalk router indicates in its data a "downstream line rate" of 64,592 kbits/s VDSL2.

When I used BT the comparable downstream line rate was greater than 75,000 kbits/s.

Since the cabinet is Openreach, should this rate be identical irrespective of ISP or is there a contributory factor from the ISP itself that can alter this downstream line rate?

mwarby

It's all down to the chipset in your router some are better than others. I found when I had VDSL2 that broadcom baaed routers gave a higher sync than lantiq based ones

Nothing much your isp or openreach can do, unless they give you a better modem. If then 10 meg means a lot to you, you could try getting your own, or seeing if your old modem can be reconfigured to work with talktalk (they won't be much if any help if you go down this route)

mwarby

Assumimg you have a homehub try (apparently it works on 4 and 5 too)

https://community.plus.net/t5/Broadband/Do-want-to-use-a-BT-Homehub-3-or-2-on-Plusnet-ADSL-or-FTTC/m-p/988213

your username will be as below (taken from talktalk site)

Username: this will be your telephone number followed by @talktalk.net - for example, 1234567891@talktalk.net

password https://help2.talktalk.co.uk/check-your-broadband-password

Sterlingtimes

mwarby wrote: »

It's all down to the chipset in your router some are better than others. I found when I had VDSL2 that broadcom baaed routers gave a higher sync than lantiq based ones

Nothing much your isp or openreach can do, unless they give you a better modem. If then 10 meg means a lot to you, you could try getting your own, or seeing if your old modem can be reconfigured to work with talktalk (they won't be much if any help if you go down this route)

Thank you, mwarby. It would help me to clarify my understanding further if you could bear with me. Are you saying that the synch figure achievable is purely a matter of negotiation between the electronics and software in the Openreach VDSL street cabinet and the ISP supplied router? And further that the ISP is totally displaced from the process in that the ISP electronics and software fall wholly outside of this process? Many thank, Sterling.

mwarby

Sterlingtimes wrote: »

Are you saying that the synch figure achievable is purely a matter of negotiation between the electronics and software in the Openreach VDSL street cabinet and the ISP supplied router?

The achevable sync speed is a function of line length, line noise and the equipment on both ends. The speed of a VDSL link will tend to drop overtime, as new subscribers tend to raise the level of noise in a bundle of cables

The ISP supplied router and openreach street cabinet negotiate the optimal sync speed, the main influence is the settings in the cabinet .An ISP can have 80/20 50/10 40/10 or 40/2 as the upper sync limit, in your case you have 80/20

This relies upon each end being able to communicate the other with a margin controlled by further setting in cabinet, in technical terms this is SNR and SNR margin and isn't influenced by the ISP.

If you imagine the difficulty of a shouting conversation you'll get the idea of SNR. You have to be heard, and be able to hear the other, exchange info as quickly as possible, without error, with background noise caused by others trying to do the same. You are limited as to volume you can use, so it comes down to how clear your voice is and how good your hearing is

Some chipset designs in routers do a better job at this than others, and some designs work better on longer lines than shorter ones or vica versa. At one time it was felt that matching the maker of the chipset in the cabinet to chipset in the router was best, but last time I looked into it the broadcom chipsets preformed best regardless. Chipset aside other design issues might be the noiseiness of power supply or processor or wifi, or the design of the frontend (the first electronics which interface with the line) these can all impact on the SNR

Sterlingtimes wrote: »

And further that the ISP is totally displaced from the process in that the ISP electronics and software fall wholly outside of this process? Many thank, Sterling.

Apart from setting the maximum speed as indicated the ISP doesnt influence the sync speed. Of course in terms of t speed as measured by a speedtest or file download, this is influenced by the ISPs network, which often extends to the exchange

Sterlingtimes

mwarby wrote: »

... ng the maximum speed as indicated the ISP doesnt influence the sync speed. Of course in terms of the speed as measured by a speedtest or file download, this is influenced by the ISPs network, which often extends to the exchange

Thank you, mwardy for kindly taking more than a few minutes out of your time to explain the situation carefully. I now appreciate (as I had speculated) that Talk Talk is not able influence the sync figure. It may be that the chip set in the Talk Talk Super Router is unable to achieve the higher sync figure that was achieved by BT Home Hub 5.

However, the Super Router has its compensations in that the radio is far better and it does not intermittently block my Reciva WIFI radio as the Home Hub did.

The sync difference is of no real concern, but I wanted to understand what was going on. The measured download speed is always very good and very consistent.

Best wishes, Sterling.