Address allocation not working correctly

Simon Hobson dhcp1 at
Wed May 7 15:24:21 UTC 2008

Corley, Kenneth L \(Kenny\) wrote:

>We are not currently using option 82.
>The giaddr is always in DHCP Discover for both STB traffic and
>data/internet traffic so the DHCP server is allocating from 10.6.0.x
>always.  I need it to allocate 10.5.0.x for STBs and 10.6.0.x for
>data/internet (ie. PCs). 
>Do you think using MAC OUI for STB address allocation would work...then
>put the scopes for data/internet and voip below in the DHCPd config file
>since it is processed from top to bottom?

Nothing will work until you fix your configuration !

If you want to run 10.5.0.x AND 10.6.0.x on the same physical network 
then that is a shared network and you MUST define the shared network 
to the DHCP server.

If you don't then the server will NEVER allocate (in this case) a 
10.5.0.x address to any device on that network<period> No matter what 
classing etc you do, 10.5.0.x addresses will not be valid for that 
network and the server will not allocate them.

Once you have done that, then the next step is to tell the DHCP 
server what to allocate to what, and that is what the classing is 
about. If it's an either/or situation, then it's sufficient to define 
one class like this :

class "someclassname" {
   match if <some condition>

shared-network "somenetworkname" {
   subnet ... {
     pool {
       range ;
       allow members of "someclassname" ;
   subnet ... {
     pool {
       range ;
       deny members of "someclassname" ;

Note that a client may match more than one class - all are evaluated, 
it is not a "start at the top and quit when something matches" setup.

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