Implementation of multiple network segments in a DHCP address pool(V7)

Network requirements

As shown in Figure 1, the DHCP server (Switch A) dynamically assigns IP addresses to clients in the LAN.

Configure two subnets in the address pool on the DHCP server: 10.1.xx.0/24 as the primary subnet and 10.xx.2.0/24 as the secondary subnet. The DHCP server selects IP addresses from the secondary subnet when the primary subnet has no assignable addresses.

Switch A assigns the following parameters:

·     The default gateway 10.1.xx.254/24 to clients on subnet 10.1.xx.0/24.

·     The default gateway 10.xx.2.254/24 to clients on subnet 10.xx.2.0/24.

Figure 1 Network diagram

Configuration procedure

# Enable DHCP.

system-view

[SwitchA] dhcp enable

# Configure the primary and secondary IP addresses of VLAN-interface 10.

[SwitchA] interface vlan-interface 10

[SwitchA-Vlan-interface10] ip address 10.1.xx.1 24

[SwitchA-Vlan-interface10] ip address 10.xx.2.1 24 sub

# Enable the DHCP server on VLAN-interface 10.

[SwitchA-Vlan-interface10] dhcp select server

[SwitchA-Vlan-interface10] quit

# Create DHCP address pool aa.

[SwitchA] dhcp server ip-pool aa

# Specify the primary subnet and the gateway address for dynamic allocation.

[SwitchA-dhcp-pool-aa] network 10.1.xx.0 mask 255.255.255.0

[SwitchA-dhcp-pool-aa] gateway-list 10.1.xx.254

# Specify the secondary subnet and the gateway address for dynamic allocation.

[SwitchA-dhcp-pool-aa] network 10.xx.2.0 mask 255.255.255.0 secondary

[SwitchA-dhcp-pool-aa-secondary] gateway-list 10.xx.2.254

[SwitchA-dhcp-pool-aa-secondary] quit

[SwitchA-dhcp-pool-aa] quit

Verifying the configuration

# Verify that the DHCP server assigns clients IP addresses and gateway address from the secondary subnet when no address is available from the primary subnet. (Details not shown.)

# Display the primary and secondary subnet IP addresses the DHCP server has assigned. The following is part of the command output.

[SwitchA] display dhcp server ip-in-use

IP address       Client identifier/    Lease expiration      Type

                 Hardware address

10.1.xx.2         0031-3865-392e-6262-  Jan 14 22:25:03 2015  Auto(C)

                 3363-2e30-3230-352d-

                 4745-302f-30

10.xx.2.2         3030-3030-2e30-3030-  Jan 14 22:25:03 2015  Auto(C)

                 662e-3030-3033-2d45-

                 7568-6572-1e