Excluding DHCP Pool IP Addresses From Dynamic Assignment On OES

  • 7007122
  • 29-Oct-2010
  • 26-Apr-2012

Environment

Novell DHCP
Novell Open Enterprise Server 2 (OES 2) Linux Support Pack 2

Situation

Under NetWare, administrators are used to creating pools, or ranges of addresses available to the DHCP server for dynamic assignment.  NetWare makes it easy to exclude addresses found in that pool or range from being assigned out dynamically (IE.  A printer on the network needs a static assignment, so the admin find the printer in the pool of addresses assigned out, and changes its assignment type to "excluded"). 

Resolution

Unlike NetWare, OES DHCP does not allow the administrator to make an assignment type of "excluded" on the hosts.  The only way to do this is to do the following:
 
To exclude an IP address , the IP address should not be a part of the Pool:
 
Example :
(Consider a Class C Subnet)
The current pool is : x.x.x.1 - x.x.x.100
The IP address that needs to be excluded is is x.x.x.45
 
The previous pool will need to be deleted and two new pools created:
Pool 1 : x.x.x.1 - x.x.x.44
Pool 2 : x.x.x.46 - x.x.x.100
 
This above given method is the only method available to exclude an IP address.  Some have created HOST assignments within the pool; however,  the server will  throw issues.  It will tell the administrator that static and dynamic leases are present for x.x.x.45 address and that one of them will need to be removed.
 
In short, the only method would be to accomplish this is to split the pool.
 
 
CONSIDERATIONS:
  1. If pools are split according to the above instructions, configuring DHCP options may be best accomplished on the subnet itself (instead of on each pool).  The scope of the subnet will encompass all of the pools, making management of the DHCP options much easier
  2. Consider configuring the "ping-check" option under the SETTINGS of the DHCP SERVER object itself.  Setting this option to TRUE will force the server to ping the address it wishes to assign out to see if there is a response first.