Configuring the DHCP server

Last Updated : Nov 06, 2012 |

Procedure

  1. Enter ip dhcp pool, followed by a number from 1 to 32, to create a DHCP pool.
  2. Use the name command to configure the pool’s name.
  3. Configure a range of available IP addresses that the DHCP server may assign to clients, using start-ip-addr to set the start IP address of the range and end-ip-addr to set the end IP address of the range.

    Consider the following:

    • For a manual/reservation pool, set identical IP addresses for the start and end IP addresses

    • The start IP address and end IP address must be on the same network according to the subnet mask

    • The start IP address must be lower than the end IP address

    • The combined number of IP addresses in all pools must not exceed 256 addresses

    • Both the start IP address and end IP address can be up to 223.255.255.255

    • The start IP address and end IP address may not be network/broadcast addresses according to the subnet mask

  4. Use the subnet-mask command to configure the subnet mask of the pool.
  5. Use the lease command to configure the lease period for IP address assignment.

    By default, the lease is eight days.

  6. For a manual/reservation pool, use the client identifier command to reserve the pool’s IP address for assignment to a specific client.

    To configure a reservation, the start IP address and end IP address must be identical. You cannot configure more than one reservation on a single pool.

  7. Configure DHCP options for the pool, if required.

    See Configuring options and, for vendor specific options, Configuring vendor-specific options.

  8. Repeat steps 1 to 7 to configure as many DHCP pools as you require.

    You can configure up to 32 DHCP pools. By default, all pools are inactive until you activate them. This enables you to modify each pool’s configuration without affecting network devices.

  9. Activate each of the DHCP pools you configured using the ip dhcp activate pool command in general context, followed by the pool number.
  10. Enter ip dhcp-server to activate DHCP server.

    DHCP server is now active. If you change the pool configuration, it is recommended to do so while the pool is active.

    Note:

    If you try to configure a new start and end IP address that is not part of the current network and beyond the allowed maximum of 256 IP addresses, first use the no start ip address and no end ip address commands before configuring the new start and end IP addresses.