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CHAPTER
2-1
Cisco uBR924 Software Configuration Guide
OL-0337-05 (8/2002)
2
DOCSIS-Bridging Configuration
This chapter describes the default configuration of the Cisco uBR924 cable access router. With this
configuration, the Cisco uBR924 router functions in its “plug and play” DOCSIS-bridging mode,
performing as a DOCSIS-compliant two-way cable modem. Every DOCSIS-compliant cable modem
provides the following minimum set of features:
• Automatically provisions and configures itself using the DOCSIS configuration file that is
downloaded from a server at the headend.
• Acts as a transparent bridge to send IP data traffic between its Ethernet and cable interfaces,
providing connectivity from the customer’s system to the Internet backbone.
• Provides Internet connectivity to PCs or other CPE devices connected to the Cisco uBR924 router.
Note In Cisco IOS Release 12.1, Voice over IP (VoIP) traffic is automatically supported when using the
DOCSIS-bridging mode. However, in Cisco IOS Release 12.0, the default “plug and play” image does
not enable the Cisco uBR924 router’s voice ports. To enable the voice ports, you must use a Cisco IOS
image with voice support and download an appropriate Cisco IOS configuration file. See Chapter 4,
“Voice over IP Configurations,” for more information.
The following sections describe the configuration for “plug and play” DOCSIS bridging:
• DHCP Server Configuration, page 2-2
• DOCSIS Configuration File, page 2-3
• Cisco IOS Software Image, page 2-6
• Cisco IOS Configuration File, page 2-7
• Configuring the Attached CPE Devices, page 2-9
• Reconfiguring DOCSIS-Compliant Bridging, page 2-9
The DHCP server configuration and DOCSIS configuration file are required for every
DOCSIS-compliant cable modem. The Cisco IOS image and configuration files are optional, depending
on the needs of the subscribers. The remaining configurations are optional, depending on the needs of
the subscribers.
The information described in this chapter applies to every Cisco uBR924 cable access router that is used
in a DOCSIS-compliant network. Additional configuration steps might be needed, however, to support
additional features, such as VoIP and IPSec encryption—this additional configuration is described in the
other chapters in this guide.