Consider the distance limitations for signaling, electromagnetic interference (EMI), and connector compatibility.
Possible cable types are fiber, thick or thin coaxial, foil twisted-pair, or unshielded twisted-pair cabling.
Also consider any additional interface equipment you need, such as transceivers, hubs, switches, modems,
channel service units (CSU), or data service units (DSU).
Before you install the router, have all the additional external equipment and cables on hand. For information
about ordering, contact a Cisco customer service representative.
The extent of your network and the distances between the network interface connections depend, in part, on
the following factors:
•
Signal type
•
Signal speed
•
Transmission medium
The distance and rate limits referenced in the following sections are the IEEE-recommended maximum speeds
and distances for signaling purposes. Use this information as a guideline when planning your network
connections
prior
to installing the router.
If wires exceed the recommended distances, or if wires pass between buildings, give special consideration to
the effect of a lightning strike in your vicinity. The electromagnetic pulse caused by lightning or other
high-energy phenomena can easily couple enough energy into unshielded conductors to destroy electronic
devices. If you have had problems of this sort in the past, you may want to consult experts in electrical surge
suppression and shielding.
Asynchronous Terminal Connections
The router provides a console port to connect a terminal or computer for local console access. The port has
an RJ-45 connector and supports RS-232 asynchronous data with distance recommendations specified in the
IEEE RS-232 standard.
Interference Considerations
When wires are run for any significant distance, there is a risk that stray signals will be induced on the wires
as interference. If interference signals are strong, they may cause data errors or damage to the equipment.
The sections describe the sources of interference and how to minimize their effects on the router.
Electromagnetic Interference
ll the equipment powered by AC current can propagate electrical energy that can cause EMI and possibly
affect the operation of other equipment. The typical sources of EMI are equipment power cords and power
service cables from electric utility companies.
Strong EMI can destroy the signal drivers and receivers in the router and even create an electrical hazard by
causing power surges through the power lines into installed equipment. These problems are rare, but could
be catastrophic.
Cisco ASR-920-12SZ-IM Aggregation Services Router Hardware Installation Guide
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Preparing for Installation
Asynchronous Terminal Connections
