Example: Configuring dynamic IP address assignment

Network configuration

As shown in Figure 20, the DHCP server (Switch A) assigns IP addresses to clients on subnet 10.1.1.0/24, which is subnetted into 10.1.1.0/25 and 10.1.1.128/25.

Configure DHCP server on Switch A to implement the following assignment scheme.

Table 3: Assignment scheme

DHCP clients	IP address	Lease	Other configuration parameters
Clients connected to VLAN-interface 10	IP addresses on subnet 10.1.1.0/25	10 days and 12 hours	Gateway: 10.1.1.126/25 DNS server: 10.1.1.2/25 Domain name: aabbcc.com WINS server: 10.1.1.4/25
Clients connected to VLAN-interface 20	IP addresses on subnet 10.1.1.128/25	Five days	Gateway: 10.1.1.254/25 DNS server: 10.1.1.2/25 Domain name: aabbcc.com

Figure 20: Network diagram

Procedure

IMPORTANT:

By default, interfaces on the device are disabled (in ADM or Administratively Down state). To have an interface operate, you must use the undo shutdown command to enable that interface.

Specify IP addresses for the VLAN interfaces. (Details not shown.)

Configure the DHCP server:

# Exclude the DNS server address, WINS server address, and gateway addresses from dynamic allocation.

<SwitchA> system-view
[SwitchA] dhcp server forbidden-ip 10.1.1.2
[SwitchA] dhcp server forbidden-ip 10.1.1.4
[SwitchA] dhcp server forbidden-ip 10.1.1.126
[SwitchA] dhcp server forbidden-ip 10.1.1.254

# Configure DHCP address pool 1 to assign IP addresses and other configuration parameters to clients on subnet 10.1.1.0/25.

[SwitchA] dhcp server ip-pool 1
[SwitchA-dhcp-pool-1] network 10.1.1.0 mask 255.255.255.128
[SwitchA-dhcp-pool-1] expired day 10 hour 12
[SwitchA-dhcp-pool-1] domain-name aabbcc.com
[SwitchA-dhcp-pool-1] dns-list 10.1.1.2
[SwitchA-dhcp-pool-1] gateway-list 10.1.1.126
[SwitchA-dhcp-pool-1] nbns-list 10.1.1.4
[SwitchA-dhcp-pool-1] quit

# Configure DHCP address pool 2 to assign IP addresses and other configuration parameters to clients on subnet 10.1.1.128/25.

[SwitchA] dhcp server ip-pool 2
[SwitchA-dhcp-pool-2] network 10.1.1.128 mask 255.255.255.128
[SwitchA-dhcp-pool-2] expired day 5
[SwitchA-dhcp-pool-2] domain-name aabbcc.com
[SwitchA-dhcp-pool-2] dns-list 10.1.1.2
[SwitchA-dhcp-pool-2] gateway-list 10.1.1.254
[SwitchA-dhcp-pool-2] quit

# Enable DHCP.

[SwitchA] dhcp enable

# Enable the DHCP server on VLAN-interface 10 and VLAN-interface 20.

[SwitchA] interface vlan-interface 10
[SwitchA-Vlan-interface10] dhcp select server
[SwitchA-Vlan-interface10] quit
[SwitchA] interface vlan-interface 20
[SwitchA-Vlan-interface20] dhcp select server
[SwitchA-Vlan-interface20] quit

Verifying the configuration

# Verify that clients on subnets 10.1.1.0/25 and 10.1.1.128/25 can obtain correct IP addresses and all other network parameters from Switch A. (Details not shown.)

# On the DHCP server, display the IP addresses assigned to the clients.

[SwitchA] display dhcp server ip-in-use
IP address       Client identifier/    Lease expiration      Type
                 Hardware address
10.1.1.3         0031-3865-392e-6262-  Jan 14 22:25:03 2015  Auto(C)
                 3363-2e30-3230-352d-
                 4745-302f-30
10.1.1.5         0031-fe65-4203-7e02-  Jan 14 22:25:03 2015  Auto(C)
                 3063-5b30-3230-4702-
                 620e-712f-5e
10.1.1.130       3030-3030-2e30-3030-  Jan 9 10:45:11 2015   Auto(C)
                 662e-3030-3033-2d45-
                 7568-6572-1e
10.1.1.131       3030-0020-fe02-3020-  Jan 9 10:45:11 2015   Auto(C)
                 7052-0201-2013-1e02
                 0201-9068-23
10.1.1.132       2020-1220-1102-3021-  Jan 9 10:45:11 2015   Auto(C)
                 7e52-0211-2025-3402
                 0201-9068-9a
10.1.1.133       2021-d012-0202-4221-  Jan 9 10:45:11 2015   Auto(C)
                 8852-0203-2022-55e0
                 3921-0104-31

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