failover

[richard lucassen]

Hello list,

I'm busy configuring two machines of which only one will connect to an
ISP on a /25 network using dhclient.

On the active machine eth2 is up, on the backup machine eth2 is down
(and vice versa of course)

In order to get the same ip (which is important) I need to query from
the same MAC address (that's no problem). But when trying this here at
home using isc-dhcp-server (Debian Bookworm, I have no idea which dhcp
server the ISP has) I get different ip addresses, even though the
MAC,uid and hostname are the same:

lease 203.0.113.64 {
  starts 5 2022/01/28 13:36:21;
  ends 5 2022/01/28 13:46:21;
  cltt 5 2022/01/28 13:36:21;
  binding state active;
  next binding state free;
  rewind binding state free;
  hardware ethernet 00:0d:b9:21:ba:d8;
  uid "af-pw failover";
  client-hostname "af-pw";
}
lease 203.0.113.64 {
  starts 5 2022/01/28 13:36:21;
  ends 5 2022/01/28 13:36:33;
  tstp 5 2022/01/28 13:36:33;
  cltt 5 2022/01/28 13:36:21;
  binding state free;
  hardware ethernet 00:0d:b9:21:ba:d8;
  uid "af-pw failover";
}
lease 203.0.113.65 {
  starts 5 2022/01/28 13:36:46;
  ends 5 2022/01/28 13:46:46;
  cltt 5 2022/01/28 13:36:46;
  binding state active;
  next binding state free;
  rewind binding state free;
  hardware ethernet 00:0d:b9:21:ba:d8;
  uid "af-pw failover";
  client-hostname "af-pw";
}
lease 203.0.113.65 {
  starts 5 2022/01/28 13:36:46;
  ends 5 2022/01/28 13:36:51;
  tstp 5 2022/01/28 13:36:51;
  cltt 5 2022/01/28 13:36:46;
  binding state free;
  hardware ethernet 00:0d:b9:21:ba:d8;
  uid "af-pw failover";
}

I added this to the original Debian dhclient.conf file:

backoff-cutoff 2;
initial-interval 1;
send dhcp-client-identifier "af-pw failover";
send host-name = "af-pw";

Why is the dhcp server providing two different addresses?

Richard.

-- 
richard lucassen
http://contact.xaq.nl/