Configuring Bridging
Configuring the Cisco uBR900 Series Cable Access Routers 41
Configuring Bridging

The Cisco uBR900 series cable access router is configured for DOCSIS-compliant transparent

bridging by default. If it becomes necessary to reconfigure the unit for bridging after it has been

configured for routing, you can erase the routing configuration and return the unit to factory default

configuration settings, or you can reconfigure the unit manually using the CLI. To return the cable

access router to factory default settings, see the section “Reestablishing DOCSIS-Compliant

Bridging” on page43 for details. To reconfigure the cable access router manually, perform the

following tasks, starting in global configuration mode:

Step Command Purpose
1uBR924(config)#no service pad Disable packet assembler/disassembler commands;
prevent the uBR900 series from accepting incoming or
outgoing Packet Assembler/Disassembler (PAD)
connections.
2uBR924(config)#no service password-encryption Disable password encryption.
3uBR924(config)#no ip routing Disable IP routing on the uBR900 series.
4uBR924(config)#interface Ethernet0 Enter interface configuration mode for the Ethernet0
interface.
5uBR924(config-if)#no ip address Disable the IP address on the Ethernet0 interface.
6uBR924(config-if)#no ip route-cache Disable high-speed switching caches for IP routing.
7uBR924(config-if)#bridge-group bridge-group Assign the Ethernet0 interface to a bridge group. The
bridge group must be an integer between 1 and 63.
8uBR924(config-if)#bridge-group bridge-group
spanning-disabled
Disable spanning tree on the Ethernet interface.
9uBR924(config-if)#end
uBR924(config)#interface cable-modem0
Exit interface configuration mode for the Ethernet0
interface and enter interface configuration mode for the
cable access router interface.
10 uBR924(config-if)#no ip address Disable the IP address of the coaxial cable interface, if
one has been set. The uBR7246 cable router assigns an IP
address to the cable access router each time it connects to
the network.
11 uBR924(config-if)#no ip route-cache Disable high-speed switching caches for IP routing on the
cable interface.
12 uBR924(config-if)#no keepalive Disable keepalives on the cable interface.
13 uBR924(config-if)#cable-modem compliant bridge Enable DOCSIS-compliant bridging.
14 uBR924(config-if)#bridge-group bridge-group Assign the cable access router interface to a bridge group.
The bridge group must be an integer from 1 to 63. (The
default is 59.)
15 uBR924(config-if)#bridge-group bridge-group
spanning-disabled
Disable spanning tree on the cable interface.
16 uBR924(config-if)#end
uBR924(config)#ip classless
Exit interface configuration mode.
(Optional) At times, the uBR900 series might receive
packets destined for a subnet of a network that has no
network default route. This global configuration mode
command allows the Cisco IOS software to forward such
packets to the best network route possible.
17 uBR924(config)#line console 0 Enter line configuration mode to configure the console
port.