lost speed

[#1]

My line speed is nearly 2 Meg lower than my sync speed, why should this be? It can't be overheads because if someone sync speed was 2 Meg or less they would have no line speed.

[#2]

Hi glloyd,

Are you using a wifi connection?

[#3]

Hi @glloyd as your line is in sync at 16760, this would give a profile of around 14700 as the profile is set at 88% of the sync speed.

A sync speed of 2Mbps would give a profile of 1760.

I hope this clears things up

[#4]

Not really, why are why do we loose 12% of our sync speed. That's a lot for overheads.

[#5]

No, 

[#6]

More information on the IP Profile can be found here: http://www.kitz.co.uk/adsl/IPprofile.htm

The IP profile is a limit put in place calculated from your sync speed, minus an allowance for various protocol overheads. The profile is applied at the BT bRAS to restrict the downstream data traffic speed on the backhaul between the bRAS and DSLAM.

Why does BT apply an IP / bRAS profile?

The simple answer is to stop traffic bottle-necking at the exchange backhaul VP (or SVLAN for FTTC).
A maximum throughput level is needed to stop more data than your line can physically achieve being sent down the backhaul and causing packets to be dropped at the DSLAM.