3-4
CiscouBR924 Software Configuration Guide
OL-0337-05 (8/2002)
Chapter3 Advanced Data-Only Configurations
Routing with DHCP Server
no service finger
!
!
line con 0
transport input none
line vty 0 4
!
end
Note The above configuration assumes that the DHCP server assigns an IP address to the cable interface that
is in the class A private network (10.0.0.0).
Routing with DHCP Server
When in routing mode, the Cisco uBR924 router can act as a DHCP server for the CPE devices it is
connecting to the cable network. A service provider then does not h ave to be concerned about providing
IP addresses to all of the PCs at a subscriber’s site; instead, the provider supplies a pool of IP addresses
that the CiscouBR924 router then allocates to the PCs as needed.
Note The Cisco uBR924 router must be configured for routing mode to act as a DHCP server. If in bridging
mode, you can configure the router to proxy DHCP client requests t o the DHCP server at the headend
by giving the cable helper-address dhcp-server-ip-address host interface configuration command. (The
ip helper-address and ip forward-protocol interface configuration commands can also be used for this
purpose.)
To configure the CiscouBR924 router to act as a DHCP server, log in to the router, enter global
configuration mode, and enter the following commands:
Command Purpose
Step1 uBR924(config)# ip dhcp pool pool-name Create an address pool for the DHCP server named
pool-name and enter DHCP configuration mode.
Step2 uBR924(config-dhcp)# network IP-network-number
subnet-mask
Specify the network number and subnet mask for the IP
address pool. These IP addresses should be part of the
subnet provided by the CMTS cable interface. For
example, network 10.17.91.0 255.255.255.0 reserves the
IP addresses 10.17.91.1–10.17.91.254 for CPE devices.
Step3 uBR924(config-dhcp)# domain-name domain-name The domain name that should be assigned to CPE devices
(for example, cisco.com).
Step4 uBR924(config-dhcp)# dns-server ip-address The IP address for the DNS server provided by the service
provider that will service the DNS requests from the CPE
devices. More than one DNS server can be specified.
Step5 uBR924(config-dhcp)# default-router ip-address The IP address for the default router for the CPE devices
(typically, this is the CMTS). More than one default router
can be specified.
Step6 uBR924(config-dhcp)# exit Return to global configuration mode.
Step7 uBR924# show startup-config Display the configuration file that was just created.