Exponential Lease Time

Glenn Satchell glenn.satchell at uniq.com.au
Thu Sep 6 02:52:55 UTC 2012


This is going to increment on every packet from the client, so perhaps you
need to test for the request-type using option dhcp-message-type. See
dhcp-options man page for possible values. Perhaps only increment on
DHCPREQUEST type? So a big if statement around the sections that increment
renewal.

if option dhcp-message-type = 3 {
  if renewal = 3 {
    ...
  }
} else {
  default ....
}

regards,
-glenn

On Thu, September 6, 2012 2:31 am, Nicholas F Miller wrote:
> Here are some observations from my testing. The results are not consistent
> enough to be used in production but it is still pretty interesting.
>
> 1) I haven't seen one lease that had a renewal = 1. They all seem to start
> with a renewal = 2 (Windows and Mac clients, wired and wireless). This may
> be a result of using helper addresses on the routers and WISM2s.
> 2) iPhones seem to jump straight to the longest lease time (if renewal =
> 3).
> 3) Windows phones jump straight to the second longest lease time (if
> renewal = 2).
> 4) Android phones behave the same as Windows and Mac clients.
>
> Here are the values I used for my testing which were defined in the pool
> statement:
>
>         if renewal = 3 {
>                 default-lease-time 86400;
>                 max-lease-time 86400;
>
>         } elsif renewal = 2 {
>                 default-lease-time 14400;
>                 max-lease-time 14400;
>                 set renewal = 3;
>
>         } elsif renewal = 1 {
>                 default-lease-time 3600;
>                 max-lease-time 3600;
>                 set renewal = 2;
>
>         } else {
>                 default-lease-time 900;
>                 max-lease-time 900;
>                 set renewal = 1;
>         }
>
> _________________________________________________________
> Nicholas Miller, OIT, University of Colorado at Boulder
>
>
>
>
> On Aug 31, 2012, at 2:42 PM, Norman Elton wrote:
>
>>> Out of interest, does processing that sequence of statements create
>>> more or
>>> less load than just processing renewals without dynamic lease lengths ?
>>
>> Definitely deserves further testing. We've done some scripting before
>> and it didn't contribute to a noticeable load.
>>
>>> Also, when the lease expires, does "renewal" stay set or does it get
>>> removed
>>> from the lease record ?
>>
>> After the lease expires, it appears that the "renewal" variable gets
>> wiped. Again, this could use some more testing.
>>
>> I pretty much hacked this up. I'd love some feedback from folks who
>> are more familiar with how the variables work and are designed to be
>> used.
>>
>> Norman
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>
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