On Wed, 2006-06-14 at 10:27 -0400, Phillip Susi wrote:

Jesper Dangaard Brouer wrote:

quoted

The Linux traffic's control engine inaccurately calculates
transmission times for packets sent over ADSL links.  For
some packet sizes the error rises to over 50%.  This occurs
because ADSL uses ATM as its link layer transport, and ATM
transmits packets in fixed sized 53 byte cells.

I could have sworn that DSL uses its own framing protocol that is 
similar to the frame/superframe structure of HDSL ( T1 ) lines and over 
that you can run ATM or ethernet.  Or is it typically ethernet -> ATM -> 
HDSL?

Nope, not according to the ADSL standards G.992.1 and G.992.2.

In any case, why does the kernel care about the exact time that the IP 
packet has been received and reassembled on the headend?

I think you have misunderstood what the rate table does...
(There is an explaination in the thesis page 57 section 6.1.2)
http://www.adsl-optimizer.dk/thesis/

-- 
Med venlig hilsen / Best regards
  Jesper Brouer
  ComX Networks A/S
  Linux Network developer
  Cand. Scient Datalog / MSc.
  Author of http://adsl-optimizer.dk