IP Networking

lease-file-name "/etc/dhcpd.leases";
default-lease-time 43200;  # 12 hours
max-lease-time 86400;      # 24 hours
one-lease-per-client true;

subnet 10.1.1.0 netmask 255.255.255.0 {
pool {
   failover peer "failover";
   range 10.1.1.100 10.1.1.200;
   deny dynamic bootp clients;
}
   option subnet-mask 255.255.255.0;
   option broadcast-address 10.1.1.255;
   option routers 10.1.1.1;
   default-lease-time 86400;
   max-lease-time 518400;
}

# dhcpd.conf for primary dhcp server:
failover peer "failover" {
   primary;
   address 10.1.6.71;
   port 647;
   peer address 10.1.5.71;
   peer port 647;
   max-response-delay 60;
   max-unacked-updates 10;
   mclt 3600;
   split 128;
   load balance max seconds 3;
}
 
# dhcpd.conf for secondary dhcp server:
failover peer "failover" {
   secondary;
   address 10.1.5.71;
   port 647;
   peer address 10.1.6.71;
   peer port 647;
   max-response-delay 60;
   max-unacked-updates 10;
   load balance max seconds 3;
}

 
The mclt statement

mclt seconds; The mclt statement defines the Maximum Client Lead Time. It must be specified on the primary, and may not be specified on the secondary. This is the length of time for which a lease may be renewed by either failover peer without contacting the other. The longer you set this, the longer it will take for the running server to recover IP addresses after moving into PARTNER-DOWN state. The shorter you set it, the more load your servers will experience when they are not communicating. A value of something like 3600 is probably reasonable, but again bear in mind that we have no real operational experience with this.