• To avoid noise interference in network interface cables, do not route them directly across or along power
cables.
Site Wiring Guidelines
When planning the location of the router, consider distance limitations for signaling, electromagnetic
interference (EMI), and connector compatibility. If the wiring is run for any significant distance in an
electromagnetic field, interference can occur between the field and the signals on the wires. Poor wiring can
cause:
• Radio interference emanating from the wires.
• Strong EMI, especially when caused by lightning or radio transmitters. EMI can destroy the signal drivers
and receivers in the router, and can even create an electrical hazard by conducting power surges through
lines and into equipment.
To predict and remedy strong EMI, you may need to consult with experts in radio frequency interference
(RFI).
Note
Site wiring is unlikely to emit radio interference if you use twisted-pair cable with a good distribution of
grounding conductors. Use a high-quality twisted-pair cable with one ground conductor for each data signal,
when applicable.
Give special consideration to the effect of a lightning strike in your vicinity, especially if the wiring exceeds
the recommended distances, or if it passes between buildings. The electromagnetic pulse (EMP) caused by
lightning or other high-energy phenomena can easily induce enough energy into unshielded conductors to
destroy electronic devices. If you have experienced EMP problems in the past, you may want to consult experts
in electrical surge suppression and shielding.
Most data centers cannot resolve infrequent but potentially catastrophic problems without pulse meters and
other special equipment. In addition, these problems can take a great deal of time to identify and resolve. We
recommend that you take the necessary precautions to avoid these problems by providing a properly grounded
and shielded environment, with special attention to issues of electrical surge suppression.
Chassis Air Flow Guidelines
Refer to the
Cooling System Functional Description
section in the
Cisco ASR 9000 Series Aggregation Services
Router Overview and Reference Guide
for information on fan tray and chassis air flow information.
When selecting a site to install the router, observe the following guidelines:
• Dust-free area—The site should be as dust-free as possible. Dusty environments can clog the air filter
or power supply intake vents, reducing the cooling air flow through the router. Clogged filters and vents
can cause an overtemperature condition in the router.
• Unrestricted air-flow—Allow sufficient air-flow by maintaining a minimum of 6 in (15.24 cm) of clearance
at both the inlet and exhaust openings on the chassis and the power modules. If the air flow is blocked
or restricted, or if the inlet air is too warm, an overtemperature condition can occur within the router.
Under extreme conditions, the environmental monitoring system powers off the router to protect the
components.
Cisco ASR 9000 Series Aggregation Services Router Hardware Installation Guide
9
Preparing for Installation
Site Wiring Guidelines
