In this guide, we look at network rack infrastructure, one of the fundamentals of IP video surveillance. Inside, we cover:
- What is a rack unit (RU)?
- Square vs. threaded mounting holes
- Open frame
- Closed cabinets
- Wall mount vs. floor mount
- Full vs. switch depth racks
- Rack security
- Cable trays/ladder rack
- Rack layout
- Cable management
- Passive cooling
- Active cooling
What Is a Rack Unit?
A rack unit, aka "RU" or simply "U", is the standardized unit of measurement for all networking equipment racks and hardware. It is defined as 1.75 inches/44.5mm tall by 19"/482.6mm wide, officially established as a standard in the early 1920s.
Racks and equipment are commonly specified in RUs. For example, the common standard for a full height rack is 42U or 44U. Switches, recorders, shelves, and other rack mount devices often list rack units on their spec sheets, such as this NVR:
Square Vs. Threaded Mounting Holes
Some racks use threaded holes for mounting equipment, while others use square holes which accept a captive nut (called cage nuts). Mounting rails are typically designed for one or the other, but not both of these styles.
Exposed Frame Open Racks
Exposed Frame Open Racks are lighter, cost-effective way of mounting rack hardware, also providing open access to connect wires and allowing free airflow on all sides of the equipment. There are different forms of Exposed Frame racks: