On Wed, Apr 22, 2020 at 06:00:52PM -0400, James Carlson wrote: > On 2020-04-22 13:45, David Balažic wrote: > > Hi! > > > > I have a router running openwrt connected to a GPON ONT, running a > > PPPoE connection (hw details below). > > This looks to be (possibly) a PPPoE failure, though there's nothing > interesting in the log messages provided. If there were an interesting > log message, it would almost certainly come somewhere (perhaps even > *minutes*) before that initial "Modem hangup" message. > > The definitive test would be to run a packet capture on the Ethernet > interface itself (*not* on the PPP interface) with something like > Wireshark and determine what happens in the lead-up to the failure. I'd > expect the system is just getting a stray PADT from the peer, if it's > some kind of PPPoE problem. > I'd also suspect that the peer just sent a PADT. That can be intentional. Some providers proactively force reconnections every x days. Though 20 hours looks like a really low timeout. You can capture PPPoE discovery packets with "tcpdump -i nic-eth1.3902 pppoed". Another possibility is that the network interface is modified (interface passed down, MTU or the MAC address changed) while the PPPoE session is established. > If it isn't, then possibly it's something else. I think that the last > time I looked at the PPPoE implementation on Linux it was a bit hokey -- > it ran PPP over a pty pair and then decoded the framing in user space > and wrote it back out over Ethernet using PPPoE. I hope it's not still > like that, as I haven't looked at it in years, but it may well be. An > internal error in that logic could also cause a "hangup" message, > although hopefully along with some kind of system log about a core file > as well. > I didn't know about that implementation. PPPoE has been implemented using PPPOX sockets since at least the beginning of the git history. > (The implementation on other platforms, such as Solaris, was a bit more > solid.) > > -- > James Carlson 42.703N 71.076W <carlsonj@xxxxxxxxxxxxxxx> >
