Chassis Air Flow Guidelines - Cisco ASR 9901 Manual

Preparing for Installation

Chassis Air Flow Guidelines

Site wiring is unlikely to emit radio interference if you use twisted-pair cable with 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 lightning strikes in your vicinity, especially if the wiring exceeds
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, and 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
Cisco ASR 9901 Router
Cool air is circulated front-to-back through the Cisco ASR 9901 Router by three fan trays located in the rear
of the router (see the following figure).
The fan trays maintain acceptable operating temperatures for the internal components by drawing in cool air
through the vents, and circulating the air through the chassis. Each power supply is also equipped with fans
that draw cool air into the front of the power supply and force warm air out of the air exhaust.
Note
See the following section for details on air flow clearance requirements for installation in an enclosed 4-post
rack.
Preparing for Installation
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