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Prashant Lakhera
Asked: 2020-02-14 15:52:31 +0800 CST

Is there is any tool/way to find out why packet is getting dropped due to an arp cache full?

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My developer hypothesis is packet is getting dropped at arp layer. We increased the default value of neigh.default.gc_thresh3 1024 --> 2048 and now everything looks good. But I want to understand is there is a way to figure it out arp packet loss.I try to search for systemtap/tools but didn't find anything. Any help is really appreciated. 

net.ipv4.neigh.default.gc_thresh3=<n>
linux arp kernel performance-tuning packet

1 Answers

  1. There is several articles about ARP table overflow. This article have good explanation. Also, you could check this bug.

    Both articles say that you should see error neighbour: arp_cache: neighbor table overflow! in your dmesg output, as it was mentioned in comment by user188737.

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