eciadsl seems to disconnect when system time is being changed backwards (either by ntpd or manually). It leaves a message like this in /var/log/daemon log:
Feb 25 04:43:28 ziv eciadsl-pppoeci: Disconnection due to line problem
(I've changed system time just before that).
I'm running Archlinux/i386 with 2.6.28 kernel, and it seemed to be the same thing on Ubuntu 8.10.