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Configure the System to be a Relay Agent
DHCP clients and servers request and offer configuration information via broadcast DHCP messages.
Routers do not forward broadcasts, so if there are no DHCP servers on the subnet, the client does not
receive a response to its request and therefore cannot access the network.
You can configure an interface on the Dell Networking system to relay the DHCP messages to a specific
DHCP server using the ip helper-address dhcp-address command from INTERFACE mode, as
shown in the following illustration. Specify multiple DHCP servers by using the ip helper-address
dhcp-address
command multiple times.
When you configure the ip helper-address command, the system listens for DHCP broadcast
messages on port 67. The system rewrites packets received from the client and forwards them via unicast
to the DHCP servers; the system rewrites the destination IP address and writes its own address as the
relay device. Responses from the server are unicast back to the relay agent on port 67 and the relay agent
rewrites the destination address and forwards the packet to the client subnet via broadcast or unicast,
depending whether the client has set or cleared the BROADCAST flag in the DHCP Client PDUs.
NOTE: DHCP Relay is not available on Layer 2 interfaces and VLANs.
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Dynamic Host Configuration Protocol (DHCP)