KB.15.15

Configuring a BOOTP/DHCP relay gateway

The DHCP relay agent selects the lowest-numbered IP address on the interface to use for DHCP

messages. The DHCP server then uses this IP address when it assigns client addresses. However,

this IP address may not be the same subnet as the one on which the client needs the DHCP service.

This feature provides a way to configure a gateway address for the DHCP relay agent to use for

DHCP requests, rather than the DHCP relay agent automatically assigning the lowest-numbered IP

address.

You must be in VLAN context to use this command, for example:

HP Switch# config

HP Switch(config)# vlan 1

HP Switch(vlan-1)#

Syntax:

ip bootp-gateway ip-addr

Allows you to configure an IP address for the DHCP relay agent to use for DHCP

requests. The IP address must have been configured on the interface.

Default: Lowest-numbered IP address

If the IP address has not already been configured on the interface (VLAN), you will

see the message shown in Example 126 (page 229).

Example 126 Example of trying to configure an IP address that is not on this interface (VLAN)

HP Switch# config

HP Switch(config)# vlan 1

HP Switch(vlan-1)# ip bootp-gateway 10.10.10.1

The IP address 10.10.10.1 is not configured on this VLAN.

Viewing the BOOTP gateway

To display the configured BOOTP gateway for an interface (VLAN) or all interfaces, enter this

command. You do not need to be in VLAN context mode.

Syntax:

show dhcp-relay bootp-gateway [vlan vid]

Displays the configured BOOTP gateway for a specified VLAN (interface.) If a

specific VLAN ID is not entered, all VLANs and their configured BOOTP gateways

display.

Example:

Example 127 (page 230) shows an IP address being assigned to a gateway for

VLAN 22, and then displayed using the show dhcp-relay bootp-gateway

command.

Configuring a BOOTP/DHCP relay gateway 229