Hi Ondrej, Great feedback, thank’s a lot for sharing it with us. Currently we are using the kernel 3.16.39-1+deb8u2, do you remember if this kernel was inside the list of complains?
We will schedule a maintenance to update the kernel in both Route Servers and see if that solves the issue. Thank you for the “debug” tip as well, I wasn’t aware that gives you that much detailed output like sending Keepalives to a peer. I will give it a shot. Best regards, Stavros Konstantaras | Sr. Network Engineer | AMS-IX M +31 (0) 620 89 51 04 | T +31 20 305 8999 ams-ix.net > On 28 Feb 2020, at 16:42, Ondrej Zajicek <[email protected]> wrote: > > On Fri, Feb 28, 2020 at 03:33:06PM +0100, Stavros Konstantaras wrote: >> HI Alarig, >> >> Thank you for sharing your experiences. I don’t have the MSS currently but >> if that was the case, wouldn’t have experienced the drops more frequently? >> Currently it happens once per month (or 0.8 per month) and contrary to your >> case which was 100% network related, in our case we don’t even see the >> reply packet being generated and leaving the box. >> >> What puzzles me also and based on the capture, is that I don’t see the >> TCP-ACK messages being sent to the customer. If BIRD opens a TCP socket >> (not a simple RAW socket), I assume that the TCP connection will be handled >> by the OS and BIRD will push data segments (BGP keep alive messages) when >> ready. >> >> But as per output, I don’t see the TCP ack messages at all. Is BIRD handling >> the TCP communication as well? > > Hi > > That is a good point. BIRD uses regular TCP socket, so if you do not see > TCP ack, then it is likely an underlying (kernel) issue. There were some > reports of IPv6 issues in recent kernels [*] > > Also, the log message: > > Feb 20 21:46:11 rs1-mng bird6: 2001:7F8:1::A500:19:7727:1: Received: Hold > timer expired > > shows that the notification message was received by the BIRD. The packet > dump shows that keepalives were not sent by BIRD side. You could enable > 'debug all' for given peer to see if BIRD tries to send keepalives. You > could also monitor state of socket using 'ss' tool. > > [*] https://bird.network.cz/pipermail/bird-users/2020-February/014270.html > > -- > Elen sila lumenn' omentielvo > > Ondrej 'Santiago' Zajicek (email: [email protected]) > OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net) > "To err is human -- to blame it on a computer is even more so."
