Dell FCX624-I Laptop User Manual


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840 PowerConnect B-Series FCX Configuration Guide
53-1002266-01
Configuring IP parameters – Layer 3 Switches
26
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. Refer to
“Configuring an IP helper address” on page 838.
Configuring the BOOTP/DHCP reply source address
NOTE
This feature is supported on PowerConnect B-Series FCX devices.
You can configure the Dell PowerConnect device so that a BOOTP/DHCP reply to a client contains
the server IP address as the source address instead of the router IP address. To do so, enter the
following command at the Global CONFIG level of the CLI.
PowerConnect(config)# ip helper-use-responder-ip
Syntax: [no] ip helper-use-responder-ip
Changing the IP address used for stamping BootP/DHCP requests
When the Layer 3 Switch forwards a BootP/DHCP request, the Layer 3 Switch “stamps” the
Gateway Address field. The default value the Layer 3 Switch uses to stamp the packet is the
lowest-numbered IP address configured on the interface that received the request. If you want the
Layer 3 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.
To change the IP address used for stamping BootP/DHCP requests received on interface 1/1, enter
commands such as the following.
PowerConnect(config)# interface ethernet 1/1
PowerConnect(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 Layer 3
Switch will place this IP address in the Gateway Address field of BootP/DHCP requests that the
Layer 3 Switch receives on port 1/1 and forwards to the BootP/DHCP server.
Syntax: ip bootp-gateway <ip-addr>
Changing the maximum number of hops to a BootP relay server
Each BootP/DHCP request includes a field Hop Count field. The Hop Count field indicates how
many routers the request has passed through. When the Layer 3 Switch receives a BootP/DHCP
request, the Layer 3 Switch looks at the value in the Hop Count field:
If the hop count value is equal to or less than the maximum hop count the Layer 3 Switch
allows, the Layer 3 Switch increments the hop count by one and forwards the request.
If the hop count is greater than the maximum hop count the Layer 3 Switch allows, the Layer 3
Switch discards the request.
To change the maximum number of hops the Layer 3 Switch allows for forwarded BootP/DHCP
requests, use either of the following methods.