Routing And Bridging - Cisco uBR924 Installation Manual

Cisco uBR924 Cable Access Router Description
The router can connect one or more computers to the Internet over the HFC cable system. Depending
on the other services purchased from the service provider, subscribers can also send voice and fax traffic
over the cable system, or they can use the cable system to link multiple sites into a secure private
company network (Intranet). Subscribers can use the Cisco uBR924 router to create high-speed,
permanent access to the Internet, without the need for telco-based services such as leased lines.

Routing and Bridging

When acting as a DOCSIS-compliant cable modem, the Cisco uBR924 router provides DOCSIS
bridging for one or more PCs and other customer premises equipment (CPE). The router ships from the
factory with a Cisco IOS software image stored in nonvolatile Flash memory that supports
DOCSIS-compliant bridging data operations.
Based on the feature licenses your company purchased, other Cisco IOS images can be downloaded
from Cisco Connection Online (CCO). These images provide additional functionality such as advanced
routing capabilities, advanced security, and Voice over IP (VoIP) support.
For most residential applications that involve basic Internet access or VoIP services, the Cisco uBR924
router is configured as a bridge. For residential and SOHO applications that involve special feature sets
such as the firewall features, or that include connection to an existing network at the site, the
Cisco uBR924 is configured as a router.
Note Cisco uBR924 cable access routers use Cisco IOS Release 12.0(4)XI or higher images.
All Cisco IOS releases that support the Cisco uBR924 router include at least one image
that supports basic DOCSIS connectivity that provides high-speed Internet data access.
Most Cisco IOS releases that support the Cisco uBR924 router also include additional
images that support VoIP connectivity, as well as advanced feature sets such as data
encryption, firewall protection, and additional router features.
The following paragraphs summarize the router's operation in both bridging and routing modes:
•
Cisco uBR924 Router Hardware Installation Guide
1-2
Bridging—When installed and configured as a bridge, the Ethernet hub ports at the rear of the
Cisco uBR924 router can be connected directly to PCs at the subscriber site in one of the following
configurations:
When using Cisco IOS Release 12.0(4)XI or higher interim builds in bridging mode, a
–
maximum of three PCs can be directly connected to the hub ports—the fourth hub port is
unused.
When using Cisco IOS Release 12.0(5)T or higher images in bridging mode, four PCs can be
–
directly connected to the hub ports.
When using Cisco IOS Release 12.0(5)T or higher images in bridging mode, up to 254 PCs can
–
be connected if one of the four Ethernet hub ports is connected to a standard 10BaseT Ethernet
hub, which then connects to additional computers (or hubs) at the site.
Regardless of the configuration, Cisco IOS software treats all four Ethernet hub ports as one
Ethernet interface. See Figure 1-1 for a typical configuration.
Chapter 1 Product Overview
OL-0338-01 (3/2000)