Comment 18 for bug 310035

had this issue too in karmic. This happened when traffic full such as bittorrent download. but when using modem's pppoe it never disconnect even traffic full. so it would be good if unchecking Send Echo Reply in network manager would remove lcp-echo-failure

log:
No response to 3 echo-requests
Serial link appears to be disconnected.
Connect time 29.7 minutes.

i hope this give some pointer to developer.