Product guide

IP Routing Features
Configuring DHCP Relay
DHCP Packet Forwarding
The DHCP relay agent on the routing switch forwards DHCP client packets to
all DHCP servers that are configured in the table administrated for each VLAN.
Unicast Forwarding
The packets are forwarded using unicast forwarding if the IP address of the
DHCP server is a specific host address. The DHCP relay agent sets the
destination IP address of the packet to the IP address of the DHCP server and
forwards the message.
Broadcast Forwarding
The packets are forwarded using broadcast forwarding if the IP address of the
DHCP server is a subnet address or IP broadcast address (255.255.255.255).
The DHCP relay agent sets the DHCP server IP address to broadcast IP address
and will be forwarded to all VLANs with configured IP interfaces (except the
source VLAN).
Minimum Requirements for DHCP Relay Operation
For the DHCP Relay agent to work, the following steps must be completed:
1. DHCP Relay is enabled on the routing switch (the default setting)
2. A DHCP server is servicing the routing switch
3. IP Routing is enabled on the routing switch
4. There is a route from the DHCP server to the routing switch and back
5. An IP Helper address is configured on the routing switch, set to the IP
address of the DHCP server on the VLAN connected to the DHCP Client.
Enabling DHCP Relay
The factory-default configuration enables DHCP. However, if DHCP has been
disabled, you can re-enable it at the Config CLI context level by entering this
command:
ProCurve(config)# dhcp-relay
To disable the DHCP Relay function, enter the command:
ProCurve(config)# no dhcp-relay
11-91