18 ms·
It may be more like one in 2^24. The first 24 bits are allocated for other things, so it depends how the address is randomised (eg if you keep the manufacturer
by joshvm 7y ago
It may be more like one in 2^24. The first 24 bits are allocated for other things, so it depends how the address is randomised (eg if you keep the manufacturer bits).
Though if you report a totally random address it probably will be closer to 2^48.
https://www.ionos.co.uk/digitalguide/server/know-how/mac-address/ https://www.ionos.co.uk/digitalguide/server/know-how/mac-add...
- zamadatix 7y agoYou should really be setting the "Locally Administered" bit to 1 when generating random MACs. This combined with the unicast bit should give you 2^46 possibilities without the chance to collide with a globally assigned address at all. https://www.hellion.org.uk/cgi-bin/randmac.pl https://www.hellion.org.uk/cgi-bin/randmac.pl
- AndyMcConachie 7y agoThe lowest order bit of the first byte must be 0 for a station MAC. If it is 1 then it is a multicast MAC which can never be a source MAC. A MAC can also never be all zeros. So I think it works out to something like (2^47)-1. I'm probably forgetting some other specifics so it might even be lower than that. There's a bunch of incorrect information on the link in parent. A simple example is that 01:00:5e:00:00:01 is NOT a valid source MAC address.