I encountered strange behavior today. Syslog is fully spammed
Dec 2 17:05:28 gw kernel: [33263.528216] mkiss: ax2: truncating oversized transmit packet! Dec 2 17:05:28 gw kernel: [33263.529380] mkiss: ax2: truncating oversized transmit packet! Dec 2 17:05:28 gw kernel: [33263.530492] mkiss: ax2: truncating oversized transmit packet! Dec 2 17:05:28 gw kernel: [33263.531606] mkiss: ax2: truncating oversized transmit packet! Dec 2 17:05:28 gw kernel: [33263.533164] mkiss: ax2: truncating oversized transmit packet! Dec 2 17:05:28 gw kernel: [33263.534454] mkiss: ax2: truncating oversized transmit packet! Dec 2 17:05:28 gw kernel: [33263.535679] mkiss: ax2: truncating oversized transmit packet! Dec 2 17:05:28 gw kernel: [33263.537071] mkiss: ax2: truncating oversized transmit packet! Dec 2 17:05:28 gw kernel: [33263.538409] mkiss: ax2: truncating oversized transmit packet!
The main issue was that i set the mtu of ax2 to 128. I do not know why, but just don`t do it. 🙂
ax2 Link encap:AMPR AX.25 HWaddr PI1LAP-3 inet addr:44.137.31.73 Bcast:44.137.31.95 Mask:255.255.255.224 UP BROADCAST RUNNING MTU:128 Metric:1 RX packets:1267 errors:0 dropped:0 overruns:0 frame:0 TX packets:198 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:10 RX bytes:253763 (247.8 KiB) TX bytes:4538 (4.4 KiB)
This is the code that generates this error. (mkiss.c)
if (len > ax->mtu) { /* Sigh, shouldn't occur BUT ... */ // translation of above: if data size of frame is GREATER than the // allowed MTU of ax25, generate the printk (print kernel error) below. - len = ax->mtu; printk(KERN_ERR "mkiss: %s: truncating oversized transmit packet!\n", ax->dev->name); dev->stats.tx_dropped++; netif_start_queue(dev);
Brian n1uro had this to say about it
It looks like this isn't a bug but a config issue on your end if I'm reading their code correctly. You're trying to squeeze 100 litres of water/minute through a hose that can only handle 50 litres/min so it's telling you that it's fragmenting your frames to fit the proper MTU.
So just set your mtu to 256.
root@gw:/etc/ax25# cat axports ax2 PI1LAP-3 19200 256 4 BBS pi8lap