[clue-tech] DSL providers

[Ken MacFerrin]

dperkins at frii.com wrote:
>>>> I've had this setup for about 6 months and am happy with FRII service
>>>> and billing.  Once you're fully setup, another suggestion is to call
>>>> Qwest and have them turn off interleaving on your line.  This is on by
>>>> default for all Qwest DSL lines and adds significant latency.  Once you
>>>> call in, they have a Qwest director that will review your request and
>>>> see if your line quality (distance, size of wire pairs, etc) is good
>>>> enough to have it removed..
>>> Now THAT's interesting!  Got any technical references for that?  (I
>>> know I've never heard of it, and sure wouldn't mind lower latency...
>>> any way I can get it.  GRIN...)
>>>
>> I definitely second that - I would love to see some info on this.
>>
> 
> Why interleave?  What are the pros and cons?
> 
> Regarding FRII, I've been using them since Techangle went under.  My Cisco
> router started acting up and they were very helpful in resolving that
> problem.  Qwest just said the line is good and it's your problem.  I can
> definitely recommend FRII.

Sorry, a little late in responding here as I've been tied up trying to
catch a flight back out of NYC (amazing how they go nuts over a little
snow and ice).

The basic benefit to interleaving is that it protects against
transmission errors and provides a more reliable connection by breaking
up and "mixing" several packets together before transmitting so that if
one packet gets corrupted, the remaining packets will still contain
enough information to recreate the corrupted packet without needing to
have data resent.  Unfortunately the mixing/de-mixing process nearly
doubles the latency of each packet.  If you have a poor physical
connection that's prone to errors then interleaving will be a good thing
as it will save packets from having to be constantly retransmitted.  If
your physical connection is good though, then it's just adding useless
latency.  I'm assuming the reason Qwest turns this on by default is
simple economics; most folks don't have a clue or care about latency so
it's not worth their time to do line testing.  In my case, turning off
interleaving dropped my average ping time from 70-80ms down to 35-45ms.

http://en.wikipedia.org/wiki/Interleaving
-Ken