Configure Options Specific to Address Pools

You can specify options using the option codes specified in RFC 2132. This pool-specific option is offered to DHCP clients as a configuration parameter. This option is offered to DHCP clients in the pool only when there is no host-specific option for the client. If this option is not configured and there is no host option, the global option is used. See RFC 2132 for the complete list of DHCP options and their corresponding codes.

In this example, the address pool is pool 1, and the subnet mask option is 255.255.0.0.

1. Create the address pool.

   SEFOS# configure terminal
   SEFOS(config)# ip dhcp pool 1
   

2. Configure option 1 (subnet mask option).

   SEFOS(dhcp-config)# option 1 ip 255.255.0.0
   SEFOS(dhcp-config)# end
   

3. View the options configured in the switch.

   SEFOS# show ip dhcp server pools
   

   The output in switch 1 is:

   Pool Id                         : 1
   -------------------------------------------
   Subnet                          : 12.0.0.0
   Subnet Mask                     : 255.0.0.0
   Lease time                      : 95400 secs
   Utilization threshold           : 50%
   Start Ip                        : 12.0.0.1
   End Ip                          : 12.0.0.100
   Exclude Address Start IP        : 12.0.0.1
   Exclude Address End IP          : 12.0.0.10
    
   Subnet Options
   --------------
   Code        :    1, Value      : 255.255.0.0
   Code       :     6, Value      : 12.0.0.6
   Code       :    15, Value      : future
   Code       :    44, Value      : 12.0.0.7
   Code       :    46, Value      : 1