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Sppeds Higher than Max achievable

Aspiring Pro
Posts: 621
Thanks: 39
Fixes: 3
Registered: ‎30-08-2007

Sppeds Higher than Max achievable

been watching my speed closely since switch to 21CN a couple of days ago. Have been struggling to understand all the various speeds and am now bewildered. Latest BT test shows:
21 Mbps Max Achievable Speed
Download speedachieved during the test was - 11.66 Mbps
For your connection, the acceptable range of speeds is 4 Mbps-21 Mbps.
IP Profile for your line is - 11.91 Mbps
832 Kbps Max Achievable Speed
Upload speed achieved during the test was - 1.16Mbps
Additional Information:
Upstream Rate IP profile on your line is - 832 Kbps
Router says:
Bandwidth (Up/Down) [kbps/kbps]: 1,268 / 13,497
Is the router more up to date than BT?
Posts: 878
Thanks: 1
Registered: ‎14-08-2009

Re: Sppeds Higher than Max achievable

The "bandwidth" stated on the router is actually the line synchronisation speed.
A sync speed of 13497 is exactly consistent with an IP profile setting of  11910.
and a real achievable download speed of 11660.
The router's figure is usually referred to as the line speed or connection rate and is the speed at which the router interfaces with the exchange at.
Due to data overheads/checksums and error checking traffic on the line the real download speed you get is always lower under all circumstances.
This lowered limit to take account of the 'overheads' is the IP profile speed, however it is rare that people actually do really get the IP profile speed in practice as a download speed - as your result shows.