Cisco 7000 Installation Instructions Manual page 14

Prerequisites
Rack Dimensions and Site Layout
For complete site requirements and recommendations, refer to the Cisco 7000 Hardware Installation
and Maintenance or Cisco 7507 Hardware Installation and Maintenance publications. To help
maintain trouble-free operation, consider the following precautions when planning your rack
installation:
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Rack Ventilation
Planning a proper location for the router and the layout of your equipment rack is essential for
successful system operation. Equipment placed too close together or inadequately ventilated can
cause overtemperature conditions inside the chassis. In the chassis, the cooling air is drawn in
through the front of the chassis, and the exhaust air is forced out the back between the interface
processor faceplates.
The following guidelines are recommended to ensure a sufficient flow of cooling air to the chassis:
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14 Cisco 7000 and Cisco 7507 Rack-Mount Kit Installation Instructions
Place the chassis in a location with sufficient access to power and network interface cables. Avoid
straining cables or routing them near traffic paths or power cables (which can cause interference).
During the installation, allow sufficient working space around the rack. You will need at least
three feet in front of the rack to lift the chassis and insert it, and two feet of clearance outside the
power supply bays to insert power supplies.
After installation, allow at least two to three feet of clearance behind the rack for maintenance.
Because the interface processor end of the router provides access to the power switches,
processor slots, and status LEDs, we recommend that you mount the interface processor end at
the most accessible side of the rack. You should be able to access both ends of the router without
having to remove it from the rack.
Some equipment racks provide a power strip along the length of one of the rear mounting strips.
If your rack has this feature, consider the position of the strip when planning fastener points and
determine whether you will install the chassis from the front or the rear of the rack. Power
supplies are installed in the rear of the chassis, and a power strip might partially block access to
the bay.
If your rack is enclosed, or if it has a door on the front, temporarily remove the door to provide
enough clearance for installation. If the rack does not provide a rear door for access to the rear
chassis panel, install the chassis backwards in the rack so you can access the FRUs and spare
parts, and view the LEDs.
Place the chassis in a location that enables the flow of cooling air through the chassis. The chassis
blower draws cooling air in through the front chassis panel, past the internal components, and out
the back panel. Inhibiting the intake, blocking the exhaust, or allowing heated air to enter the
intake can cause overtemperature conditions and cause the system to shut down.
Because the intake and exhaust ports for cooling air are located on the front and rear of the
chassis, multiple chassis can be stacked with little or no clearance in a rack. You can remove the
four feet on the chassis after the chassis is mounted in the rack.
Install the chassis in an open rack whenever possible. If installation in an enclosed rack is
unavoidable, ensure that the rack has adequate ventilation or an exhaust fan.
Conversely, a ventilation system that is too powerful in a closed rack may also prevent cooling
by creating negative pressure around the chassis and redirecting the air away from the chassis
intake vent. If necessary, operate the chassis with the rack open.
Equipment near the bottom of a rack may generate excessive heat that is drawn upward and into
the intake ports of equipment above, leading to overtemperature conditions in the chassis at or
near the top of the rack.