> There is always the fact that ADSL is half > duplex where as SDSL is full duplex. You would see this as a problem if > you were trying to download something and upload something at the same > time. Your circuit can only do one thing at a time thus somethi > ng will have to wait. You will see this if you are able to FTP a large > file out to a system on the net fast, close to your maximum, yet your VoIP > (SIP?) traffic will start having problems at less than the maximum rate > that the physical link can handle.
Err, since when is ADSL half duplex ? News to me :) I think you'll find if you read up on (A)DSL that it is in fact full duplex. Going from memory, the frequency range from 25Khz up to 1.1Mhz is broken up into a fairly large number of subcarriers (52 I think ?) and some subcarriers are used for the downstream direction (the majority in the case of ADSL, or half of them for SDSL) while the rest are used for the upstream direction. Because it uses frequency division muliplexing for each carrier to exist on the line simultaneously there is no need to do any time division multiplexing between upstream and downstream. Besides, even a normal modem dialup connection is full duplex, it's unlikely ADSL would take a backwards step from that ;-) Regards, Simon _______________________________________________ LARTC mailing list LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc
