the 2Wire looks to have some reference to INP on G.dmt too.
Googling around I found "A significant portion of the end-to-end delay in high-rate DSL systems is due to the impulse noise protection scheme employed in order to shield those systems against random, non-stationary noise bursts of high energy that appear on the copper lines. Systems are protected from impulse noise using a combination of interleaving and Reed-Solomon codes
. In order to lower the end-to-end delay without reducing the data rate that is available to the user, one needs to decrease the interleaver depth. This paper presents a way to achieve this reduction without compromising neither the robustness to noise bursts nor the data rate of the system. The proposed algorithm relies on the inner code used by many DSL systems and uses the metric provided by the inner code decoder at the receiver."
I've certainly seen Reed-Solomon options on some modems.
A Billion router mentions INP http://www.billion.uk.com/product/wireless/7402gl.htm
even has an icon for it !
666 kbytes/s with Demon
predominantly over fibre
Get all this Microsoft Lame! stuff off my PC !