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DHCP server failover with dynamic bootp range declaration

cn flag
Yakup

I am trying to configure a failover for a ISC dhcp server running on Linux that has dynamic-bootp range declaration.

The configuration file looks like this (I am trying it locally first, therefore private ranges):

authoritative;
log-facility local7;
shared-network "vm-net" {
failover peer "failover-partner" {
     secondary;
     address 192.168.122.4;
     port 647;
     peer address 192.168.122.3;
     peer port 647;
     max-response-delay 60;
     max-unacked-updates 10;
     load balance max seconds 3;
}
  subnet 192.168.122.0 netmask 255.255.255.128 {
      pool {
          failover peer "failover-partner";
          max-lease-time 1800;
          range 192.168.122.0 192.168.122.127;
      }   
    deny unknown-clients;
  }
  subnet 192.168.122.128 netmask 255.255.255.128 {
      pool {
          failover peer "failover-partner";
          max-lease-time 1800;
          range dynamic-bootp 192.168.122.128 192.168.122.255;
      }   
    deny unknown-clients;
  }
}

However the daemon reload fails with the following syslog error message:

Dec  7 14:59:07 dhcpmaster1 dhcpd[4397]: range declarations where there is a failover
Dec  7 14:59:07 dhcpmaster1 dhcpd[4397]: peer in scope.   If you wish to declare an
Dec  7 14:59:07 dhcpmaster1 dhcpd[4397]: address range from which dynamic bootp leases
Dec  7 14:59:07 dhcpmaster1 dhcpd[4397]: can be allocated, please declare it within a
Dec  7 14:59:07 dhcpmaster1 dhcpd[4397]: pool declaration that also contains the "no
Dec  7 14:59:07 dhcpmaster1 dhcpd[4397]: failover" statement.   The failover protocol
Dec  7 14:59:07 dhcpmaster1 dhcpd[4397]: itself does not permit dynamic bootp - this
Dec  7 14:59:07 dhcpmaster1 dhcpd[4397]: is not a limitation specific to the ISC DHCP
Dec  7 14:59:07 dhcpmaster1 dhcpd[4397]: server.   Please don't ask me to defend this
Dec  7 14:59:07 dhcpmaster1 dhcpd[4397]: until you have read and really tried to understand
Dec  7 14:59:07 dhcpmaster1 dhcpd[4397]: the failover protocol specification.
Dec  7 14:59:07 dhcpmaster1 dhcpd[4397]: Configuration file errors encountered -- exiting

Does it mean, that ISC dhcp protocol does not support failover of dynamic ranges? Or is there any other way how to configure it?

I can not find any further information in the man pages and isc.org appears to be down/unreachable.

Any advise would be appreciated.

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NiKiZe

From your own log output:

The failover protocol itself does not permit dynamic bootp - this is not a limitation specific to the ISC DHCP server. Please don't ask me to defend this until you have read and really tried to understand the failover protocol specification.

The failover protocol do not support bootp failover, so it is not limited to ISC DHCP server.

Reading https://datatracker.ietf.org/doc/html/draft-ietf-dhc-failover-12#page-42 gives some more insights.

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Yakup avatar
cn flag
Yakup
Thanks for the documentation link. If it could be helpful to anyone facing a similar problem, I have split the `dynamic-bootp` range into two sub-ranges, different from the failover pool range, and placed each on one of the failover partners. It seems to work well.
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