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Chapter 29. DHCP L2 Relay and L3 Relay | 488
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29. DHCP L2 Relay and L3 Relay
This chapter includes the following sections:
• DHCP L2 Relay
• DHCP L3 Relay on page 494
• Configure a DHCP L3 Switch on page 499
DHCP L2 Relay
DHCP relay agents eliminate the need to have a DHCP server on each physical network.
Relay agents populate the giaddr field and also append the Relay Agent Information
option to the DHCP messages. DHCP servers use this option for IP addresses and other
parameter assignment policies. These DHCP relay agents are typically IP routing-aware
devices and are referred to as Layer 3 relay agents.
In some network configurations, there is a need for Layer 2 devices to append the relay
agent Information option as they are closer to the end hosts.
DHCP Server #1
Host #1
Host #2
Layer 2 Switch #1
1/0/4
1/0/5
1/0/6
Figure 47. DHCP L2 Relay