Riverstone Networks WICT1-12 - Manual (Page 113)

Riverstone Networks RS Switch Router User Guide Release 8.0 7-1
7 CMTS CONFIGURATION GUIDE
This chapter describes how to connect and configure Riverstone’s Cable Modem Termination System (CMTS).
The CMTS interface is an RS 8000/8600 series module that supports one transmit (downstream) and four receive
(upstream) ports. The RS 8000/8600 chassis with the CMTS module provides wire-speed CMTS integration.
Riverstone offers an integrated CMTS that is DOCSIS and EuroDOCSIS compliant, enabling cable MSOs to
provide data transmission over a two-way cable TV (HFC) infrastructure.
7.1 HFC CABLE NETWORK ARCHITECTURE
The architecture of a two-way hybrid fiber coaxial (HFC) network is based on the traditional one-way HFC-cable
network. The headend is the cable distribution center. The traditional HFC cable headend provides the broadcast
of television channels. These channels are comprised of input signals such as off-air channels, satellite channels,
local community programming, and local advertisement insertion. With the Riverstone CMTS module and an
intermediate frequency (IF) to-radio frequency (RF) upconverter installed at the headend, digital data can be
transmitted over the same infrastructure as the traditional television channels. The Riverstone CMTS downstream
ports transmit IF signals to the upconverter, which translates the signals to RF. The translated signal are then
processed for distribution with the television signals.
Receivers, scamblers, and descramblers process the television signals to encode or decode them as needed for
broadcast. Modulators format the television and digital signals.
The analog and digital signals then pass through the RF combiner (cables, amplifiers, and taps the headend) and
are broadcast from the headend through the optical transmitters to optical fiber nodes in the network. Amplifiers,
coaxial cable, and taps carry the signals to the subscriber’s premises. The analog signals are received by cable set
top boxes, televisions, and VCRs as they are in one-way HFC networks. Digital signals are received by cable
modems that are connected to the subscribers computers via 10BaseT Ethernet cables.
On the upstream path, the cable modems transmit RF signals back through additional amplifiers to optical fiber
receivers at the headend. These receivers pass the upstream signal to the upstream ports on the Riverstone CMTS
where they are processed. For example, the upstream signal might be a request to access a worldwide web page
on the Internet.
7.2 CMTS MODULE DESCRIPTION
The front panel of the CMTS module shown in Figure 7-1 has five connectors. Connectors US 1 through US 4 are
for connecting the upstream inputs. The connector labeled IF DS is for connecting the downstream output. LEDs
located on the front panel operate in a LAN centric manner. The green LED indicates that a link is established and
a yellow LED indicates that a packet is being transmitted or received.