Routing Operations - Cisco uBR905 Installation Manual

Chapter 1 Product Overview
Figure 1-1
For better network performance, Cisco recommends a maximum limit of 16 CPE devices
Note
in either bridging or routing mode. The service provider can also set a different limit by
changing the MAX CPE parameter in the DOCSIS configuration file—the default MAX
CPE value is one CPE device.

Routing Operations

When configured as a router, the Cisco uBR905 can be connected directly to four PCs via the Ethernet
hub ports at the rear of the router. One of the four Ethernet hub ports can also be connected to a standard
10BaseT Ethernet hub, which then connects additional computers or Ethernet devices at the site to a
local area network (LAN). (See Figure 1-2.)
Figure 1-2
In routing mode, the Cisco uBR905 is typically configured to use the IP address of the headend router
as its default IP gateway. Routing mode does not have a maximum limitation on the number of CPE
devices, as is the case in bridging mode; however, the CMTS can still limit the number of CPE devices
by limiting the number of IP addresses that any particular cable modem can provide services for. If this
is the case, the Cisco uBR905 router can use NAT/PAT translations to use one IP address for multiple
CPE devices.
OL-0598-01 (9/2000)
Cisco uBR905 in a Bridging Configuration
CATV
coaxial cable
HFC
network
Cisco uBR900 series
cable access router
Cisco uBR905 in a Routing Configuration
CATV
coaxial cable
HFC
network
Cisco uBR900 series
cable access router
Overview of the Cisco uBR905 Cable Access Router
PC
Ethernet
PC
Ethernet
PC
Ethernet
PC
Ethernet
Ethernet Ethernet
Hub
PC
Cisco uBR905 Router Hardware Installation Guide
PC
1-3