problem with dhcp failover

[Nicolas Ecarnot]

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