Troubleshooting guide

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Cisco Broadband Local Integrated Services Solution Troubleshooting Guide
OL-5169-01
Chapter 1 Solution Overview
Solution Components
Hybrid Fiber-Coax (HFC) Network
The HFC infrastructure, which is provisioned and maintained by the Multiple Service Operator (MSO),
is responsible for providing a high speed link to the headend for multiple households. Voice data packets
traversing the BLISS for Cable solution initially pass over a neighborhood cable network referred to as
an HFC network. The fiber node receives electrical signals from all households passed and transforms
them into an optical signal for a high-speed transfer to the hub/ headend. Figure 1-3 displays the
components in a typical HFC network.
Figure 1-3 HFC Cable Network
The HFC network is composed of a combination of fiber optic lines and nodes , standard commercial
grade coaxial cable, amplifiers, and so on needed to interconnect household communication devices
(including telephones, personal computers, television sets, and fax machines) to HFC hubs. The HFC
distribution network topology is strictly MSO-specific.
The following physical devices/interfaces will usually be encountered on a typical HFC cable network:
• Coaxial Cable—The physical, broadband network cable used within a subscriber’s premises and
the headend.
• Taps—Taps are the origination point of the HFC network’s “last mile” connection to the customer’s
residence. Taps are the local tie-in point located along the street outside of the customer’s residence
where the cable MSOs can initiate and/or terminate the residential coaxial cable connection that
connects the cable backbone running through a neighborhood to an individual premises.
• Fiber/Optic Nodes—The coaxial cable that connects to the subscribers’ premises is terminated at
a fiber node. Fiber nodes are responsible for providing high-speed links to the Hub/Headend for
multiple households.
– In the upstream direction, the fiber node converts the electrical signal it receives from the coax
network to an optical signal.
– In the downstream direction, the fiber node converts the optical signal it receives from the
CMTS to an electrical signal that it sends out on the coax network.
• RF amplifiers—In order to support a reliable two-way traffic flow over the HFC network, you must
ensure that the network is equipped with bidirectional amplifiers to pass voice packets back and
forth between the MTA at the voice customer’s residence and the local cable headend CMTS.
Two-way RF amplifiers boost the downstream and upstream signal strength on the HFC network.
Note Some older cable network installations feature only single-direction data amplifiers that can
only pass data in the downstream direction. These types of HFC networks do not meet Cisco’s
BLISS for Cable solution requirements.
transmitter
receiver
transmitter
receiver
Fiber node
Electrical Optical
Express
amplifier
Bridge
amplifier
TapTap
Line
extender
Coax tree and
branch
network
Hub
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