ARP fixes #544
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ARP fixes #544
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On paper this looks great, and in a sane network it should work. However the world out there is full of horribly broken, screwed up networks, which *of course* ruin this. I've seen a customer's network where the router is IP 192.168.1.1, MAC addr xx:03. However, every 1 minute the router broadcasts some "mikrotik discovery" UDP garbage with source IP 192.168.1.1, source MAC addr xx:02 (one less!). This accidentally poisons smoltcp's ARP cache, which then sends all traffic for the default gateway to xx:02, which unsurprisingly blackholes it. And, of course, the broadcast is every 1min and the ARP cache lifetime is 1min. This means the cache is almsot all the time poisoned, and the smoltcp device barely works. Fantastic. Screw you mikrotik.
- Mirrors what Linux does, so will hopefully reduce problems in broken networks. - it can actually increase performance: for small ARP caches, it'll reduce the amount of entries that we're not going to use, increasing the chances of the ones that we actually use to stay in the cache. Fixes #537
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bors r+ |
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