on a ccr2004-16G-2s+ i have quite a bit of rx overflow on my wan interface.
Round about 0.5% of all rx packages.
The explanation in the mikrotik documentation says that it can happen when device resources are insufficent, but it’s just a gigabit link handeling between 100-500 Mbit/s of traffic mostly around 1400-1500 in size. Cpu Load is usually between 5-15% sometimes hitting 30%, never more. Also in the forum i found the explenation that this can happen if the outgoing interface is congested, but that can’t be the case either since those are all gigabit as well and traffic only flows from wan to serveral internal interfaces and back. Also some of the internal interfaces have rx overflow, which could be explained by microcongestion of the wan but the other way around it doesn’T make sense at all to me. Does anyone have more insights on this or similar issues? The counter also does increase often at only around 100mbit of incoming traffic. At such speeds the router shouldn’t have any recource limitations.
I find this very wired since even L009 doesn’t have any RX-Overflow at 250mbit while my ccr2004 does have already from 100mbit on. Only difference being Full table on CCR2004 while the L009 only has a default route.
It can happen that interrupts are disabled for some reason, and packets come in.
For example, I know that in the RB5009 (which is in the same performance class), the interrupts are disabled during flash erase. When you do “copy partition” the whole router is dead for like 2 seconds, and all input results in rx overflow. Routing protocols that use BFD see a failed connection, etc.
Normally I do not see that on the CCR2004 but maybe there are other situations.