MAC randomisation and DHCP pools

Gregory Sloop gregs at
Mon Jul 27 18:40:40 UTC 2020

MP> As an aside,

MP> I fail to see the use case for long reservations in the first place.  Lower the
MP> lease time and move on with life.

I think the question is: What's a long reservation? 7 days hardly ever seems appropriate. But the same is true for, say 2m.

If you set 10m reservations and have a problem with the DHCP server, it's going to be a *REALLY* big problem in 10m. (Oops!) 
[Don't ask me how I know this! :) ]

So, I tend to pick reservation times with an eye toward giving me some breathing room should a DHCP server die or otherwise have problems. 
But for pools of IP's with a lot of churn, that comes up against lease exhaustion. 

There's no really great universal answer. You're right, at least on the surface, Matt - shorter reservations are helpful. But it's not a one-ended calculation - where shorter is almost universally better. It's a trade-off.

And to expand the pool of options (pun intended) - How about a bigger address pool as an option? I think in most of the cases where we're talking Wifi pools with high churn, a bigger pool isn't that hard to come by . And then, churn isn't as large a problem and super short leases aren't as critical.
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