It looks like /etc/init/network-interface.conf from ifupdown should probably exclude ppp interfaces. It appears to be intended for hotplug, and ppp interfaces look like they're hotplugged, but in fact they're typically created as a result of an ifup invoking pppd. They need a way to be protected from automatic ifdown if they're persistent.
Adding ifupdown to the bug. ** Also affects: ifupdown Importance: Undecided Status: New -- pppd persistent mode is not working https://bugs.launchpad.net/bugs/578108 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs