H3C Technologies H3C SecPath F1000-E - Manual (Page 41)

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DHCP Server Configuration
This chapter includes these sections:
• Introduction to DHCP Server
• DHCP Server Configuration Task List
• Displaying and Maintaining the DHCP Server
• DHCP Server Configuration Examples
• Troubleshooting DHCP Server Configuration
NOTE:
The DHCP server configuration is supported only on Layer 3 Ethernet interfaces (or subinterfaces), VLAN
interfaces, Layer 3 aggregate interfaces, and loopback interfaces.
Introduction to DHCP Server
Application Environment
The DHCP server is well suited to the network where:
• It is hard to implement manual configuration and centralized management.
• The hosts are more than the assignable IP addresses and it is impossible to assign a fixed IP address
to each host. For example, an ISP limits the number of hosts accessing the Internet at a time, so lots
of hosts need to acquire IP addresses dynamically.
• A few hosts need fixed IP addresses.
DHCP Address Pool
Address pool types
DHCP address pools can be classified into two types:
• Common address pool: Supports both static binding and dynamic allocation.
• Extended address pool: Supports dynamic allocation only.
Common address pool structure
In response to a client’s request, the DHCP server selects an idle IP address from an address pool and
sends it together with other parameters such as the lease time and a DNS server address to the client.
The common address pool database is organized as a tree. The root of the tree is the address pool for
natural networks, branches are address pools for subnets, and leaves are addresses statically bound to
clients. For the same level address pools, a previously configured pool has a higher selection priority
than a new one.
At the very beginning, subnetworks inherit network parameters and clients inherit subnetwork
parameters. Therefore, common parameters, for example a DNS server address, should be configured at
the highest (network or subnetwork) level of the tree.