pool range utilization

[Simon Hobson]

Yannick CHAMPS <yannick at viti.pf> wrote:

> But reducing the poll range size is not the best option for me.

That's not suggested as a permanent change - just to spread the clients during the initial phase of address assignment. So to start with, you might try :

  pool {
              range 172.16.128.1 172.16.130.255;
              range 172.16.136.1 172.16.137.255;
              range 172.16.144.1 172.16.145.255;
              range 172.16.152.1 172.16.153.255;
              allow members of "lte_internet";
           }
and monitor the pool utilisation closely - in this case, I've left more on teh lower numbered range to give a little bit of leeway). The 3 higher numbers ranges will fill up fairly fast, and as the lowest one starts to fill, you add address to all the ranges :
  pool {
              range 172.16.128.1 172.16.131.255;
              range 172.16.136.1 172.16.138.255;
              range 172.16.144.1 172.16.146.255;
              range 172.16.152.1 172.16.154.255;
              allow members of "lte_internet";
           }
rinse and repeat ...

That will spread new clients across the ranges, and will also spread "old" leases (addresses that have been used, but the client has gone away) across the ranges. Over time, the pool utilisation will become as close to random as you are likely to get - and with large numbers of users, your link utilisation will probably be statistically even.
But be aware that this will not achieve load balancing as such, just something that overall gives something with that appearance.


I have thought of another option. If you create dummy leases for every address in your ranges, each flagged as expired and with random end times, then that would also prime the system with random lease assignments. But you'll need to knock up a script to create the extra leases - they only need very basic information, just enough to make the DCHP server load them and treat the addresses as used.
I don't know if the leases need to have a hardware address in them, if they do, then try and use a range of dummy addresses that are unlikely to be found in practice - I don't know if there is a reserved range of MAC addresses for experimental or documentation use.