Installation guide

1-6
Cisco uBR7100 Series Universal Broadband Router Software Configuration Guide
OL-2238-03
Chapter 1 Overview
Operating Standards for Cisco IOS Software
DOCSIS-compliant cable plants that support North American channel plans use ITU J.83 Annex B RF.
Figure 1-1 illustrates a DOCSIS two-way and telco-return architecture.
Figure 1-1 DOCSIS Two-Way and Telco-Return Architecture
Larger cable companies typically have high-speed fiber backbones that carry Internet data, voice, and
video between the following cable company facilities:
• Regional processing centers
• Headends
• Hubs
The fiber backbone can be made up of OC-3 (155 Mbps) to OC-48 (2488 Mbps) Synchronous Optical
Network (SONET) or Asynchronous Transfer Mode (ATM) rings. The backbone network can connect to
other networks, including the Public Switched Telephone Network (PSTN), other cable system
backbones, or to public Internet interconnect points that multiple ISPs use.
The CMTS Media Access Control (MAC) domain typically includes one or more downstream paths and
one or more upstream paths. Depending on the CMTS configuration, the CMTS MAC domain can be
defined to have its downstreams on one cable modem card with its upstreams on another card, or one or
more CMTS MAC domains per cable modem card.
Cisco provides high-speed routers to route interactive traffic between the backbone and Ethernet in the
headend internal network. Signaling protocols maintain the network intelligence needed to route traffic
optimally, automatically building and maintaining routing tables to direct traffic and signal failures for
rerouting in the network.
Border Gateway Protocol (BPG) typically operates between the cable operator’s regional network and
external networks, providing routing information exchange between different networks. The Open
Shortest Path First (OSPF) protocol is used in regional networks usually. Cisco routers incorporate
Cisco IOS software, which offers advanced software features, including quality of service (QoS),
Weighted Fair Queuing (WFQ), and IP multicast.
PSTN
Telco return
access
Distribution hub or headend
Operation
support system
Cable modem
termination system
(CMTS)
Mod
Demod
Downstream
RF interface
Upstream
RF interface
Video 1
Video 2
Data
Data
Upstream
splitter
and filter
bank
Controller
50-860 MHz
NTSC
5-42MHz
NTSC
Coax
Fiber
Tx
Distribution
network
Node
RF
interface
Telco
return
Cable modem
telco return
interface
34972
Cable
modem
Rx
Network
termination
Security &
access
controller
Port
Adapter
Local
server
facility
WAN
WAN
Remote
server
facility
Backbone
network
Node
Node
Data over
cable service
specification
(DOCSIS)