2-9
Hardware Installation Guide for the Cisco 4000 Series  Integrated Services Router
OL-32185-02
Chapter 2      Cisco 4000 Series ISRs Preinstallation
  Rack Requirements
Physical Characteristics
Be familiar with the physical characteristics of the Cisco  4451-X ISR to assist you in placing the system 
in the proper location. 
Table 2-2 shows the weight and dimensions of the Cisco  4451-X ISR.
The following list describes additional Cisco  4451-X ISR chassis characteristics:
• Chassis height meets EIA-310 rack spacing 2RU (3.5 inches/88.90 mm.), universal rack-mount
• Chassis width meets EIA-310 19-inch (17.25 inches/438.15 mm) wide with rack brackets
• Cable-management brackets at each Cisco  4451-X ISR locations can hold 16 ports of STP/UTP RJ 
45 cables 
• Cable-management brackets allow a bend radius of 1.5 inches for cables
• Adjustable rack-mount brackets allow for a front to rear rail variance distance of 15.50/394mm to 
19.00/482.6mm 
Rack Requirements
Some Cisco routers include brackets for use with a 19-inch rack or, if specified in your order, optional 
larger brackets for use with a 23-inch rack. 
The following information can help you plan your equipment rack configuration:
• Allow clearance around the rack for maintenance.
• Allow at least one rack unit of vertical space between routers.
• Enclosed racks must have adequate ventilation. Ensure that the rack is not congested, because each 
router generates heat. An enclosed rack should have louvered sides and a fan to provide cooling air. 
Heat generated by equipment near the bottom of the rack can be drawn upward into the intake ports 
of the equipment above it. 
• When mounting a chassis in an open rack, ensure that the rack frame does not block the intake or 
exhaust ports. If the chassis is installed on slides, check the position of the chassis when it is seated 
in the rack. 
Tabl e 2-2 Physical Characteristics of Cisco  4451-X ISRs
Characteristics Cisco  4451-X ISRs 
Height 3.5 in. (8.89 cm.)—2RU rack-mount 
Width 17.25 in. (43.815 cm.)—19-inch rack-mount 
Depth 18.7 in. (47.498 cm.)
(including card handles, cable-management brackets, power supply 
handles)
Weight 38-40 lbs (17.23-18.14 kg)