66 Brocade ICX 6650 Layer 3 Routing Configuration Guide
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Configuring IP parameters – Layer 3 Switches
•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, a Brocade Layer 3 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 Layer 3 Switch will allow to a value from 1 through 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. Refer to “Configuring
an IP helper address” on page64.
Configuring the BOOTP and DHCP reply source address
You can configure the Brocade 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.
Brocade(config)# ip helper-use-responder-ip
Syntax: [no] ip helper-use-responder-ip
Changing the IP address used for stamping BootP and 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 1/1/1,
enter commands such as the following.
Brocade(config)# interface ethernet 1/1/1
Brocade(config-if-e10000-1/1/1)# ip bootp-gateway 192.168.22.26
These commands change the CLI to the configuration level for port 1/1/1, then change the
BootP/DHCP stamp address for requests received on port 1/1/1 to 192.168.22.26. 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 1/1/1 and forwards to the BootP/DHCP server.
Syntax: ip bootp-gateway ip-addr