Ethernet Connector And Cabling - Cisco uBR924 Installation Manual

Ethernet Connector and Cabling

additional outlets, the condition and length of the cable's center conductor, and the quality of the cable
can negatively affect the connectivity and performance of the cable access router for digital data
transmission.
For example, a 5 dB reduction in signal quality for analog downstream video might cause a slight
degradation of picture clarity, which might or might not be noticeable to a subscriber. However, a
reduction of only 1 dB in signal quality for digital data might completely disrupt service to a
Cisco uBR924 router user.
Cisco recommends that you use a headend-grade coaxial cable or a quad-shield coaxial cable with a
minimum of 60% + 40% braid and double foil insulation to connect the cable modem cards to the HFC
network. The center conductor must be straight and extend 1/8 inch (3.2 mm) beyond the end of the
connector, and the connector should be securely crimped to the cable. The following cables are
recommended:
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All three of the coaxial cables listed can be used to connect a Cisco cable modem card to
Note
the HFC network; however, the consistent use of RG-59 cable is preferred. If you connect
an RG-59 cable to a cable modem card that was previously connected using RG-6 cable,
the difference in the center connector diameter might cause intermittent connectivity loss.
If you use different types of coaxial cable, the following problems can appear:
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Refer to the Cisco uBR924 Cable Access Router Software Configuration Guide for
Note
additional configuration and site requirement information related to the setup of the analog
RF signal and digital data.
Ethernet Connector and Cabling
The Cisco uBR924 router provides four RJ-45 connectors that provide the following Ethernet 10BaseT
connectivity:
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Cisco uBR924 Router Hardware Installation Guide
B-2
RG-59—0.034 inch (0.86 mm) center conductor diameter
RG-59/U—0.0226 inch (0.57 mm) center conductor diameter
RG-6—0.041 inch (1.05 mm) center conductor diameter
Co-channel interference—If signals at the same frequency are carried on long, parallel runs of
coaxial cable, interference can occur between the signals. Higher quality cable helps to prevent this
with better shielding. Co-channel interference is seen as hum or patterns in analog video channels
and intermittent data loss in digital channels.
Damage to Cisco uBR7200 series cable modem card connectors—The modem card connectors are
designed for RG-59 or RG-6 cable and connectors. Larger cables can damage the connectors.
High signal return loss—High quality cable and correct connectors help to ensure an optimal return
loss of 16 dB or higher.
When the router is configured for either routing or bridging mode, up to four computers or other
customer premises equipment, such as IP-capable printers, can be connected directly to the router,
one device per connector. Use straight-through cables for these connections.
Appendix B Connector and Cable Specifications
OL-0338-01 (3/2000)