My ISP, like many others, is using the technique of terminating the users' PPPoE connection after 24 hours. I would obviously like to have the highest availability possible. I manually arranged the restart to happen early in the morning and also tuned the config option lcp-echo-interval 3 to get a quicker reconnect.
However, this is not a truly satisfactory solution. Is there a way to make Linux buffer outgoing packets until the connection is re-established, rather than sending back the ICMP Destination network unreachable? There may also be other caveats I'm not yet sure of, like netfilter dropping the connections table when the ppp0 interface disappears.
EDIT: I have the necessary prerequisites for this to work in principle, like a static IP every time. How do I stop the ICMP errors, keep the NAT table and, optionally, also buffer at least non-bulk packets?