problem: host with fixed- and dynamically allocated address at the same time

[Tarik Gasmi]

Hello,

i'm currently setting up a central dhcp service (isc dhcpd version 3.1.0
under gentoo linux) for different departments of the university i'm
working at and stuck with the following problem:

some clients have fixed addresses in some subnets but don't get dynamic
adresses in other subnets with dynamic pools and free leases.
for example a notebook-computer most of the time in one office (fixed
address, dns fqdn), but sometimes taken to a unknown and changing number
of different subnets covered by the same central dhcp service.

first some information about my service configuration:

- service is running with failover between 2 servers
- the dhcpd.conf file contains global and failover config data
- rest of the configuration is splitted in different include files, each
one containing subnet/pool/host declarations for a specific department
(all included in dhcpd.conf)
- host declarations are not in scope of subnet declarations


here an example from my dhcp config:
***************************************
in one include-file:
subnet-A .... {
  ....
}
host foo {
   hardware ethernet aa:aa:aa:aa:aa:aa;
   fixed-address subnet-A-ip;
}
host foo-dyn {
   hardware ethernet aa:aa:aa:aa:aa:aa;
}

in a different include-file:

subnet-B .... {
   pool {
      failover peer "dhcp-failover";
      deny dynamic bootp clients;
      range subnet-B-IP subnet-B-IP;
      deny unknown-clients;
   }
}
****************************************

host foo most of the time in Subnet A doesn't get a dynamic IP in Subnet
B when its plugged on to that subnet in a different department.


I would like to cite from the dhcpd.conf man page:

chapter: REFERENCE: DECLARATIONS
...
part: The host statement
...
If a client is to be booted using a fixed address if it's possible, but
should be allocated a dynamic address otherwise, then a host declaration
must be specified without a fixed-address declaration. hostname should
be a name identifying the host. If a hostname option is not specified
for the host, hostname is used.
...

first i had only one host declaration with a fixed-address for that
host. then i realized the problem. then i added a second one for the
same client, the matching criteria is the hardware address.

is there something i misunderstood?

thank you in advance for perhaps giving me some hints or help ...

best regards,
tarik gasmi