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4. On receiving DHCPREQUEST, the DHCP server responds with a DHCPACK packet via DHCP relay
to the DHCP client.
DHCP Relay Configuration Task List:
1. Enable DHCP relay.
2. Configure DHCP relay to forward DHCP broadcast packet.
1. Enable DHCP relay.
service dhcp
DHCP server and DHCP relay is enabled as the
2. Configure DHCP relay to forward DHCP broadcast packet.
ip forward-protocol udp bootps
no ip forward-protocol udp bootps
The UDP port 67 is used for DHCP broadcast
Interface Configuration Mode
ip helper-address <ipaddress>
no ip helper-address <ipaddress>
Set the destination IP address for DHCP relay
forwarding; the “no ip helper-address
<ipaddress>“command cancels the setting.
29.4 DHCP Configuration Examples
Scenario 1:
Too save configuration efforts of network administrators and users, a company is using switch as a DHCP
server. The Admin VLAN IP address is 10.16.1.2/16. The local area network for the company is divided into
network A and B according to the office locations. The network configurations for location A and B are shown
below.
Default gateway 10.16.1.200
Default gateway 10.16.1.200
In location A, a machine with MAC address 00-03-22-23-dc-ab is assigned with a fixed IP address of
10.16.1.210 and named as “management”.
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