求救！！adsl-start连上就断。怎么连都是这样。

adobe

adsl-start刚连上就断了
输入adsl-status返回:
Note: You have enabled demand-connection; adsl-status may be inaccurate.
adsl-status: Link is attached to ppp0, but ppp0 is down
或：
Note: You have enabled demand-connection; adsl-status may be inaccurate.
adsl-status: Link is down -- could not find interface corresponding to
pppd pid 2405

输入adsl-status返回:
Note: You have enabled demand-connection; adsl-status may be inaccurate.
adsl-status: Link is attached to ppp0, but ppp0 is down
或：
Note: You have enabled demand-connection; adsl-status may be inaccurate.
adsl-status: Link is down -- could not find interface corresponding to
pppd pid 2405

bigcat00

试试ifup ppp0