The cabinet or rack must meet these requirements:

• Standard 19-inch (48.3 cm) (two- or four-post EIA cabinet or rack, with mounting rails that conform to English universal hole spacing per section 1 of ANSI/EIA-310-D-1992). For more information, see Requirements specific to perforated cabinets.

  The spacing between the posts of the rack must be (EIA-310-D-1992 19-inch rack compatible) wide enough to accommodate the width of the chassis.

• The minimum vertical rack space requirement per chassis is:

  • For a one RU (rack unit) switch, 1.75 inches (4.4 cm)

  • For a one and a half RU (rack unit) switch, 2.63 (6.68 cm)

  • For a two RU (rack unit) switch, 3.5 inches (8.8 cm)

  • For a three RU (rack unit) switch, 5.25 inches (13.3 cm)

• The width between the rack-mounting rails must be at least 17.75 inches (45.0 cm) if the rear of the device is not attached to the rack. For four-post EIA racks, this measurement is the distance between the two front rails.

Four-post EIA cabinets (perforated or solid-walled) must meet these requirements:

• The minimum spacing for the bend radius for fiber-optic cables should have the front-mounting rails of the cabinet offset from the front door by a minimum of 3 inches (7.6 cm).

• The distance between the outside face of the front mounting rail and the outside face of the back mounting rail should be 23.0 to 30.0 inches (58.4 to 76.2 cm) to allow for rear-bracket installation.