DHCP (Dynamic Host Configuration Protocol) is used for assigning dynamic IP address to devices on a network. IP addresses are automatically assigned using the concept of a lease, which is the amount of time the IP address is valid for a device.
All IM and ACM Opengear devices host a DHCP server. However this server by default is disabled. The DHCP server enables the automatic distribution of IP addresses to devices on the Management LAN that are running DHCP clients. To enable the DHCP server:
- On the System: IP menu select the Management LAN page and click the Disabled label in the DHCP Server field (or go to the System: DHCP Server menu and check Enable DHCP Server )
- Enter the Gateway address that is to be issued to the DHCP clients. If this field is left blank, the Opengear device's IP address will be used
- Enter the Primary DNS and Secondary DNS address to issue the DHCP clients. Again if this field is left blank, the Opengear device's IP address is used, so leave this field blank for automatic DNS server assignment
- Optionally enter a Domain Name suffix to issue DHCP client
- Enter the Default Lease time and Maximum Lease time in seconds. The lease time is the time that a dynamically assigned IP address is valid before the client must request it again
- Click Apply
The DHCP server will sequentially issue IP addresses from a specified address pool(s):
- Click Add in the Dynamic Address Allocation Pools field
- Enter the DHCP Pool Start Address and End Address and click Apply
The DHCP server also supports pre-assigning IP addresses to be allocated only to specific MAC addresses and reserving IP addresses to be used by connected hosts with fixed IP addresses. To reserve an IP addresses for a particular host:
- Click Add in the Reserved Addresses field
- Enter the Hostname, the Hardware Address (MAC) and the Statically Reserved IP address for the DHCP client and click Apply
When DHCP has initially allocated hosts addresses it is recommended to copy these into the pre-assigned list so the same IP address will be reallocated in the event of a reboot.