Timeline for Possible UDP MTU problems (UDP, bad length 1650 > 1368 in tcpdump)
Current License: CC BY-SA 3.0
10 events
| when toggle format | what | by | license | comment | |
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| Oct 8, 2019 at 12:41 | comment | added | andresp | udp-fragmentation-offload doesn't say whether fragmentation is enabled or not, but if it is being offloaded to the NIC. IP fragmentation is affected by a flag in the header (DF) and MTU discovery (sysctl ip_no_pmtu_disc). | |
| Dec 17, 2017 at 14:34 | comment | added | Akkumulator | Looks ok then. You are synced and receiving TX. Notice that the bad length also shows on properly working systems. Currently (17.12.17) 1-10 transactions per seconds are common. | |
| Dec 17, 2017 at 14:30 | comment | added | Daniel F | What goes into Grafana/InfluxDB is the SNMP from and to the node as seen at the Firewall (i/o graphing could be reversed though, in the graph). | |
| Dec 17, 2017 at 14:30 | comment | added | Daniel F | But wouldn't that drop all the UDP traffic for transactions? I updated the answer with some info on the neighbors (tx counts). I think it is working, but as a noob I expected much more traffic. | |
| Dec 17, 2017 at 14:13 | comment | added | Akkumulator | If any component in you network chain does not support fragmentation, the paket will be dropped. Can you check if it supports fragmentation? | |
| Dec 17, 2017 at 13:56 | comment | added | Daniel F | The Firewall has a MTU of 1520 | |
| Dec 17, 2017 at 13:48 | comment | added | Daniel F |
Also, Internet -> Cable-Modem/Gateway(=NAT) -> Firewall(=2nd NAT) -> Host -> VirtualBox -> Docker Container -> Node, so this is a setup one wouldn't want to use. In about a week I will move to a VPS. VirtualBox is bridged to an Intel NIC with Jumbo frames set to 9k.
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| Dec 17, 2017 at 13:46 | comment | added | Daniel F |
For eth0 I get udp-fragmentation-offload: off [fixed] and docker0 udp-fragmentation-offload: on. When I tcpdump on eth0 I never see any traffic at all from none of the servers/clients, docker0 has all the traffic on the host.
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| Dec 17, 2017 at 13:27 | history | edited | Akkumulator | CC BY-SA 3.0 |
edited body
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| Dec 17, 2017 at 12:57 | history | answered | Akkumulator | CC BY-SA 3.0 |