R21xx-HP FlexFabric 11900 Layer 3 IP Services Configuration Guide

DHCP client configuration example

Network requirements

As shown in Figure 26, on a LAN, Switch B contacts the DHCP server through VLAN-interface 2 to obtain

an IP address, DNS server address, and static route information. The DHCP client IP address resides on

network 10.1.1.0/24. The DNS server address is 20.1.1.1. The next hop of the static route to network

20.1.1.0/24 is 10.1.1.2.

The DHCP server uses Option 121 to assign static route information to DHCP clients. Figure 25 sh

ows the

Option 121 format. The destination descriptor field contains the following parts: subnet mask length and

destination network address. In this example, the value of the destination descriptor field takes 18 14 01

01, a hexadecimal number indicating that the subnet mask length is 24 and the destination network

address is 20.1.1.0, and the value of the next hop address field takes 0A 01 01 02, a hexadecimal

number indicating that the next hop is 10.1.1.2.

Figure 25 Option 121 format

Figure 26 Network diagram

Configuration procedure

1. Configure Switch A:

# Specify the IP address of VLAN-interface 2.

<SwitchA> system-view

[SwitchA] interface vlan-interface 2

[SwitchA-Vlan-interface2] ip address 10.1.1.1 24

[SwitchA-Vlan-interface2] quit

# Enable the DHCP service.

[SwitchA] dhcp enable

# Exclude an IP address from dynamic allocation.

[SwitchA] dhcp server forbidden-ip 10.1.1.2

# Configure DHCP address pool 0 and specify the subnet, lease duration, DNS server address,

and a static route to subnet 20.1.1.0/24.

[SwitchA] dhcp server ip-pool 0