Latency Part II, continued from Part I.
According to this thread, gamers on the curent Covad RADSL 608/128 lines, with SpeedStream 5260 ADSL modems, are reporting significantly worse in ping time, than older Covad lines, and current NorthPoint SDSL products.
Covad RADSL is "rate-adaptive DMT ADSL", and the latency for this standard is typically 20ms, due to error-correcting interleaving, compared to 4ms for SDSL.
Are we stuck with this forever? How about this quote from a Cisco document on ADSL:
Therefore, ADSL provides for two logical data channels, a fast channel and a slow channel
Video traffic is directed through forward error correction and interleaving; hence, it is on a slow channel. Data traffic bypasses these functions; hence, it is on a fast channel. Bits from the two channels are multiplexed to form a composite stream that is then sent to line coding, or modulation.
How the ATU-C [DSL modem] knows to funnel data to the fast or slow channel is negotiated at startup, but the mechanisms are an unanswered question at this time." (reference).
It seems that at the moment, the RADSL equipment Covad is using is not setup by their DSLAMs (or maybe not even capable), of using the lower latency fast-path for data?