Cable Types; Distance Limitations For Interface Cables; Fast Ethernet Maximum Distance; Fxs Analog Voice Port Maximum Distance - Cisco VG224 - Analog Phone Gateway Hardware Installation Manual
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Chapter 2
Planning Your Installation
Cable Types
The cable types that are used are dependent on the Cisco VG224 voice gateway that you are using. For
more information, see the
"Cable Specifications and Information."
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Distance Limitations for Interface Cables
When planning your installation, consider distance limitations and potential electromagnetic
interference (EMI) as defined by the Electronic Industries Association (EIA). Distance limitation
information is included for the following VG ports:
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•
Fast Ethernet Maximum Distance
The maximum segment distance for Fast Ethernet is 330 feet (100 meters) (specified in IEEE 802.3).
FXS Analog Voice Port Maximum Distance
The maximum distance is established by a total allowable loop resistance, including the phone or
terminal equipment, of 600 ohms.
Interference Considerations
When you run cables for any significant distance in an electromagnetic field, interference can occur
between the electromagnetic field and the signals on the cables. This has two implications for the
installation of terminal plant cabling:
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If you use twisted-pair cables with a good distribution of grounding conductors in your plant cabling,
emitted radio interference is unlikely.
If you have cables exceeding recommended distances, or if you have cables that pass between buildings,
give special consideration to the effect of lightning strikes or ground loops. If your site has these
characteristics, consult experts in lightning suppression and shielding. The electromagnetic pulse caused
by lightning or other high-energy phenomena can easily couple enough energy into unshielded
conductors to destroy electronic devices.
Most data centers cannot resolve the infrequent, but potentially catastrophic problems just described
without pulse meters and other special equipment. Take precautions to avoid these problems by
providing a properly grounded and shielded environment and by installing electrical surge suppression.
OL-5006-04
"Interfaces and Service Capabilities" section on page 1-4
Fast Ethernet cables (RJ-45-to-RJ-45 straight-through cables)
Analog voice cables (RJ-21)
Fast Ethernet Maximum Distance, page 2-5
FXS Analog Voice Port Maximum Distance, page 2-5
Unshielded plant cabling can emit radio interference.
Strong electromagnetic interference (EMI), especially as caused by lightning or radio transmitters,
can destroy the EIA/TIA-232 drivers and receivers in the Cisco VG224 voice gateway.
Distance Limitations for Interface Cables
Cisco VG224 Voice Gateway Hardware Installation Guide
and
Appendix A,
2-5
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