Configuring IP

BootP/DHCP Forwarding Parameters

The following parameters control the routing switch’s forwarding of BootP/DHCP requests:

•Helper address – The BootP/DHCP server’s IP address. You must configure the helper address on the interface that receives the BootP/DHCP requests from the client. The routing switch cannot forward a request to the server unless you configure a helper address for the server.

•Gateway address – The routing switch places the IP address of the interface that received the BootP/DHCP request in the request packet’s Gateway Address field (sometimes called the Router ID field). When the server responds to the request, the server sends the response as a unicast packet to the IP address in the Gateway Address field. (If the client and server are directly attached, the Gateway ID field is empty and the server replies to the client using a unicast or broadcast packet, depending on the server.)

By default, the routing switch uses the lowest-numbered IP address on the interface that receives the request as the Gateway address. You can override the default by specifying the IP address you want the routing switch to use.

•Hop Count – Each router that forwards a BootP/DHCP packet increments the hop count by 1. Routers also discard a forwarded BootP/DHCP request instead of forwarding the request if the hop count is greater than the maximum number of BootP/DHCP hops allows by the router. By default, an HP ProCurve routing switch forwards a BootP/DHCP request if its hop count is four or less, but discards the request if the hop count is greater than four. You can change the maximum number of hops the routing switch will allow to a value from 1 – 15.

NOTE: The BootP/DHCP hop count is not the TTL parameter.

Configuring an IP Helper Address

The procedure for configuring a helper address for BootP/DHCP requests is the same as the procedure for configuring a helper address for other types of UDP broadcasts. See “Configuring an IP Helper Address” on page 6-69.

Changing the IP Address Used for Stamping BootP/DHCP Requests

When the routing switch forwards a BootP/DHCP request, the routing switch “stamps” the Gateway Address field. The default value the routing switch uses to stamp the packet is the lowest-numbered IP address configured on the interface that received the request. If you want the routing switch to use a different IP address to stamp requests received on the interface, use either of the following methods to specify the address.

The BootP/DHCP stamp address is an interface parameter. Change the parameter on the interface that is connected to the BootP/DHCP client.

USING THE CLI

To change the IP address used for stamping BootP/DHCP requests received on interface 1/1, enter commands such as the following:

HP9300(config)# int e 1/1

HP9300(config-if-1/1)# ip bootp-gateway 109.157.22.26

These commands change the CLI to the configuration level for port 1/1, then change the BootP/DHCP stamp address for requests received on port 1/1 to 192.157.22.26. The routing switch will place this IP address in the Gateway Address field of BootP/DHCP requests that the routing switch receives on port 1/1 and forwards to the BootP/DHCP server.

Syntax: ip bootp-gateway <ip-addr>

USING THE WEB MANAGEMENT INTERFACE

You cannot change the IP address used for stamping BootP/DHCP requests using the Web management interface.

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