3Com Switch 8800 Configuration Guide Chapter 13 DHCP Configuration
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13.3 Configuring DHCP Server
The following sections describe the DHCP server configuration tasks:
z Creating a Global DHCP IP Address Pool
z Configuring IP Address Assignment Mode
z Forbidding Specified IP Addresses to Be Automatically Assigned
z Configuring Lease Time For DHCP Address Pool
z Configuring DHCP Client Domain Names
z Configuring DNS Server Address for DHCP Clients
z Configuring NetBIOS Server Address for DHCP Clients
z Configuring NetBIOS Node Type for DHCP Clients
z Configuring Custom DHCP Options
z Configuring Outbound Gateway Address for DHCP Clients
z Configuring Parameters for DHCP Server to Send Ping Packets
Note:
Some of the above DHCP configurations can be performed for global IP address pools,
IP address pool of current VLAN interface, or IP address pools of multiple specified
VLAN interface respectively. They are:
z Configuring lease time for DHCP address pool
z Configuring DHCP client domain names
z Configuring DNS server address for DHCP clients
z Configuring NetBIOS server address for DHCP clients
z Configuring NetBIOS node type for DHCP clients
z Configuring DHCP custom options

13.3.1 Creating a Global DHCP IP Address Pool

An IP address pool contains IP addresses that can be assigned to DHCP clients. In
response to DHCP request sent by a DHCP client, the DHCP server selects an
appropriate IP address pool based on your configuration, choose an available IP
address from the pool, and sends the IP address and other parameters (such as the
lease time of the IP address) to the DHCP client. At present, you can configure up to
128 global DHCP address pools for a DHCP server.
The address pools of a DHCP server are hierarchically grouped like a tree. The root
holds the IP address of the network segment, the branches hold the subnet IP
addresses, and finally, the leaves hold the IP addresses of DHCP clients, which are
manually bound to the corresponding network adapters. Such a structure enables
configurations to be inherited. That is, configurations of the network segment can be
inherited by its subnets, whose configurations in turn can be inherited by their clients.