So I have a network where I have (2) 2116 routers in a VRRP setup. And they are working great. But what I’ve done to offload dhcp is set up a RB5009 just for dhcp. And for festivals it’s always worked great. But at the moment on one of my networks I have a /20 where it’s running DHCP. The client requested that the lease time be 10 days until the end of the event. Now I don’t know what this means for the router(dhcp server) now it does have 300 of used storage out of 1 gig so that looks safe; but the memory is 819 out of 1024mb.
Am I in trouble if they eat up and hold a few thousand of those ip addresses. I just don’t understand how the Mikrotik routers handle DHCP.
I cannot image it being a problem, but you’re right it’s not entirely clear what/if the “limit” be. One has to presume its memory, but even a DHCP record of 1-2K of data each… that still add up to few or dozen(s) MBs of RAM. And, it even being 1K might be pushing it, MikroTik is pretty efficient, so imagine closer to 100-200 bytes per for IPv4, with the last-update, client-id, etc. If using IPv6 DHCP (which you may not be), perhaps that double it (+IPv6 add’l bits) (i.e. if dual-stack it be two DHCP entries per device).
Now whether storing leases on disk would reduce memory IDK (guess: probably not, it likely just write memory to disk). But there has NOT been a lot of reports on forum of “DHCP is out-of-memory”.
If you have multiple SSID, like “staff” and “public”… perhaps you can use 10d lease time on the “staff” and leave the “public” SSID shorter if you’re worried.