ARP autodiscovery settings

[paulgear]

Need to decide whether it's a good idea to turn on ARP autodiscovery by default. LibreNMS is supposed to autodiscover things, but ARP autodiscovery might be a bit intensive. On my home install it reported on the first run of the autodiscovery: "21 devices discovered in 223.9 secs". On large networks a discovery like this could run for hours.

One option might be to limit the number of devices autodiscovered in a single run. However, because discovery only runs once every 6 hours, it might take a very long time to effectively discover a moderate-sized network.

To mitigate this, should we set a target time for full discovery, and then calculate how many hosts based on the size of the ARP tables? I could see myself trying to get too clever here...

[supertylerc]

Biggest ARP auto-discovery issue is workstations. Also multiple devices will have multiple ARP entries--recursive ARP discovery will kill ARP discovery times.

If you can specify a single device to run ARP discovery on and NOT follow the rabbit to discover other devices and specify MACs or ports to ignore as known workstations, it may be viable.

[laf]

Quite an old issue this now.

In reality are we actually seeing arp discovery issues? I've seen a few people on irc say they use it on a decent scale (no idea on numbers) and it just works?

I'd like to propose to close this if possible @paulgear

[paulgear]

Yeah - probably not much point in leaving it open; the default of off makes good sense to me.