H3C Technologies H3C S3100 Series Switches - Manual (Page 504)

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The DHCP server assigns an IP address to the client in the following order from an interface address
pool or a global address pool:
3) If there is an address pool where an IP address is statically bound to the MAC address or ID of the
client, the DHCP server will select this address pool and assign the statically bound IP address to
the client.
4) Otherwise, the DHCP server observes the following principles to select a dynamic address pool.
z If the client and the server reside in the same network segment, the smallest address pool that
contains the IP address of the receiving interface will be selected.
z If the client and the server do not reside in the same network segment (that is, a DHCP relay agent
is in-between), the smallest address pool that contains the IP address specified in the giaddr field
of the client’s request will be selected.
z If no assignable IP address is available in the selected address pool, the DHCP server will not
assign any IP address to the client because it cannot assign an IP address from the parent address
pool to the client.
DHCP IP Address Preferences
A DHCP server assigns IP addresses in interface address pools or global address pools to DHCP
clients in the following sequence:
1) IP addresses that are statically bound to the MAC addresses of DHCP clients or client IDs.
2) The IP address that was ever assigned to the client
3) The IP address designated by the Option 50 field in a DHCP-DISCOVER message
4) The first assignable IP address found in a proper DHCP address pool
5) If no IP address is available, the DHCP server queries lease-expired and conflicted IP addresses. If
the DHCP server finds such IP addresses, it assigns them; otherwise the DHCP server does not
assign an IP address.
DHCP Server Configuration Task List
Complete the following tasks to configure the DHCP server:
Task Remarks
Enabling DHCP Required
Configuring the Global Address Pool Based
DHCP Server
Configure address
pool based DHCP
server
Configuring the Interface Address Pool Based
DHCP Server
One of the two options is
required
Configuring DHCP Server Security Functions Optional
Configuring DHCP Accounting Functions Optional
Enabling the DHCP Server to Process Option 82 Optional
Enabling DHCP
You need to enable DHCP to make other related configurations take effect.
Follow these steps to enable DHCP: