Specifications

10 Release Notes for Cisco uBR904 Cable Access Router for Cisco IOS Release 12.0(7)T
New and Changed Information
Traditional dial-up networking services only supported registered IP addresses, which limited the
types of applications that could be implemented over VPNs. L2TP supports multiple protocols and
unregistered and privately administered IP addresses over the Internet. This allows the existing
access infrastructure, such as the Internet, modems, access servers, and ISDN terminal adapters
(TAs), to be used.
L2TP can be initiated wherever PPTP or L2F is currently deployed and can be operated as a client
initiated tunnel, such as PPTP, or a network access server (NAS) initiated tunnel, such as L2F.
Refer to the “Limitations and Restrictions” section for information regarding the functionality of the
Cisco uBR904 cable access router in L2TP applications.
Radio Frequency Interface MIB
The Radio Frequency Interface (RFI) MIB module is for DOCSIS-compliant radio frequency
interfaces in cable modems and CMTS. On the cable modem, RFI MIB entries provide:
• Upstream and downstream channel characteristics
• Class of service attributes
• Physical signal quality of the downstream channels
• Attributes of cable access router MAC interface
• Status of several MAC layer counters
The RFI MIB includes tables describing both the CMTS and the cable modem side of the cable
interface. All cable modem tables are implemented.
With IPSec, data can be transmitted across a public network without fear of observation,
modification, or spoofing. This enables applications such as VPNs, extranets, and remote user
access.
IPSec services are similar to those provided by Cisco Encryption Technology, a proprietary security
solution introduced in Cisco IOS Software Release 11.2. However, IPSec provides a more robust
security solution, and is standards based.
Routing (RIP V2)
A routing configuration for the Cisco uBR904 cable access router is most likely used when the cable
access router is being added to an existing personal computer network. When configured in routing
mode, the Cisco uBR904 cable access router will automatically configure the headend’s IP address
as its IP default gateway. When the IP host-routing is being configured, this automatic configuration
of the headend’s IP address as its IP default gateway will allow the Cisco uBR904 cable access router
to send packets not intended for the Ethernet interface to the headend.
RIP V2 routing is useful for small internetworks in that it enables optimization of Network Interface
Center (NIC)-assigned IP addresses by defining VLSMs for network addresses, and it allows
Classless Interdomain Routing (CIDR) addressing schema.