Minimum Requirements For Dhcp Relay Operation; Enabling Dhcp Relay; Configuring A Helper Address - HP ProCurve 5300xl Series Management Manual

IP Routing Features
Configuring DHCP Relay
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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:
HPswitch(config)# dhcp-relay
To disable the DHCP Relay function, enter the command:
HPswitch(config)# no dhcp-relay

Configuring a Helper Address

At the VLAN configuration CLI context level, enter the commands to add the
DHCP server's IP address to the VLANs list. For example, to configure a helper
address for VLAN 1, enter these commands:
HPswitch(conf)# vlan 1
HPswitch(vlan-1)# ip helper-address < ip-addr >
To remove the DHCP server helper address, enter this command:
HPswitch(vlan-1)# no ip helper-address < ip-addr >
You can configure up to 256 IP helper addresses in the switch.
For the Series 5300xl switches only, software release E.08.07 or greater is
required to support 256 IP helper addresses. Earlier releases support only 128
IP helper addresses. All other switch models covered by this guide allow 256
IP helper addresses, regardless of the software version running on the switch.