Juniper Networks M5 - Manual (Page 58)

Rack Requirements
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A 600-mm rack as defined in the four-part Equipment Engineering (EE); European
telecommunications standard for equipment practice (document numbers ETS 300 119-1
through 119-4) published by the European Telecommunications Standards Institute
(http://www.etsi.org).
The horizontal spacing between the rails in a rack that complies with this standard
are usually wider than the router’s mounting ears, which measure 19 in. (48.3 cm)
from outer edge to outer edge. Use approved wing devices to narrow the opening
between the rails as required.
The rack rails must be spaced widely enough to accommodate the router chassis’s external
dimensions: 5.25 in. (13.3 cm) high, 24 in. (61 cm) deep, and 17.5 in. (44.5 cm) wide. The
outer edges of the mounting ears extend the width to 19 in. (48.3 cm). The spacing of rails
and adjacent racks must also allow for the clearances around the router and rack that are
specified in “Clearance Requirements for Airflow and Hardware Maintenance” on page 40.
The router might not fit into an 800-mm-deep cabinet, even if you adjust the
front-to-back position of the front mounting rails inside the cabinet.
If you mount the router in a cabinet, be sure that ventilation is sufficient to
prevent overheating.
In general, a center-mount rack is preferable to a front-mount rack, because the more even
distribution of weight in the center-mount rack provides greater stability. If a front-mount
rack is used, we recommend supporting the back of the router with a shelf or other structure.
The chassis height of 5.25 in. (13.3 cm) equals 3 U, the standard rack unit defined in
Cabinets, Racks, Panels, and Associated Equipment (document number EIA-310-D) published
by the Electronics Industry Association. You can stack 14 M5 and M10 routers in a rack that
has at least 42 U (73.5 in. or 1.87 m) of usable vertical space.
The rack must be strong enough to support the weight of the fully configured router, up to
about 61 lb (27.6 kg) for the M5 router or 67 lb (29.5 kg) for the M10 router. If you stack 14
routers in one rack, it must be capable of supporting about 940 lb (427 kg).
38 M5 and M10 Internet Routers Hardware Guide