problem with dhcp failover
Nicolas Ecarnot
nicolas at ecarnot.net
Fri Dec 8 07:19:23 UTC 2017
Le 08/12/2017 à 05:53, Julie Xu a écrit :
> Hi,
>
> I have configured our dhcp pair as failover, as below:
>
> failover peer "xxx" {
>
> primary;
>
> address 10.10.10.10;
>
> peer address 10.10.10.11;
>
> port xxx;
>
> peer port xxx;
>
> max-response-delay 60;
>
> max-unacked-updates 10;
>
> mclt 300;
>
> split 128;
>
> load balance max seconds 3;
>
> auto-partner-down 0;
>
> max-lease-misbalance 15;
>
> max-lease-ownership 10;
>
> min-balance 60;
>
> max-balance 3600;
>
> }
>
> It is working good if both dhcp servers online. However, if one of the
> server is offline, than half of my ip addresses can not be renewed.
Hello,
According what I remember (I've setup a complex bunch of failovers peers
years ago), when a failover pool is setup, both servers share the pool
of ip addresses and manage its half whatever happens.
When a pair if failing, the half pool it was managing is not available
anymore : it is not assignable. The remaining server has to welcome new
requests in its remaining half pool.
Clients from the lost pool will have to issue a new query that will be
managed by the live server, but their ip will change.
Knowing this, one has to provide a large enough pool forecasting such a
case.
--
Nicolas ECARNOT
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