[AUUG-Talk]: Documenting how ADSL modems work?

Andrew Rutherford andrewr at iagu.net
Fri Sep 9 13:30:26 EST 2005

At 7:43 PM -0700 8/9/05, Michael Paddon wrote:

>I guess that there is no economic imperative for them to enable this
>functionality. After all, they would need to spend more on hardware and
>customers might settle for a slower link.

Actually, it's worse than that - there's economic imperative for them 
*not* to. Most ISP's that charge per MB charge based on bytes 
transmitted, which include headers that would otherwise be 
compressed. This may not seem like much, but over a large ISP it can 
add up to quite a bit of revenue.

This is why some ISP's preferred to deliver traffic over ethernet to 
PPP - extra framing overhead! PPPoE is the best of all worlds for 
them - maximise the framing overheads!

Was anyone else involved in the furore in University circles when 
Telstra had just taken brought the AARNet network and they redefined 
1MB from 2^20 to 10^6 because it increased their revenue by 4%?

You might be surprised how many ISP's calculate ADSL charging 
including all the padding on the end of cells. Then again, maybe you 
wouldn't be surprised. :-/

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