Contents

11 Appendix B  Cable management 11-1

General cabling requirements· 11-1

Cable binding guidelines· 11-1

Routing signal cables· 11-3

Routing MPU cables· 11-3

Routing fabric module cables· 11-4

Routing interface module cables· 11-5

Routing power cords· 11-6

 

11 Appendix B  Cable management

General cabling requirements

Minimum curvature radius of cables

·     Attached power cord, communication cable, or ribbon cable—A minimum of five times the cable’s outer diameter. If the cable is frequently bent, connected and removed, the curvature radius must be a minimum of seven times the cable's outer diameter.

·     Ordinary attached coaxial cable—A minimum of seven times the cable's outer diameter. If the coaxial cable is frequently bent, connected and removed, the curvature radius must be a minimum of 10 times the cable's outer diameter.

·     High-speed cable (SFP+ cable for example)—A minimum of five times the cable's outer diameter. If the coaxial cable is frequently bent, plugged and unplugged, the curvature radius must be a minimum of 10 times the cable's outer diameter.

Minimum curvature radius of fibers

·     When the fiber is wrapped up around the cabling plate, the diameter of the cabling plate must be a minimum of 25 times the fiber's diameter.

·     When the fiber is being moved, the curvature radius of the fiber must be a minimum of 20 times the fiber's diameter.

·     When the fiber is attached, the curvature radius of the fiber must be a minimum of 10 times the fiber's diameter.

 

	NOTE: The fiber's diameter refers to the outer diameter of the fiber jacket. Typically, the diameter of a single-core fiber is 0.9 mm (0.04 in), 2.0 mm (0.08 in), or 3.0 mm (0.12 in).

 

Cable binding guidelines

When you route and bundle up cables, follow these guidelines:

·     Label cables before you route or bundle them. For more information about labeling cables, see "Appendix E Engineering labels."

·     Bind and route the cables neatly inside the rack, and make sure they are not kinked or bent.

Figure11-1 Correct and incorrect cable binding

 

·     Route different types of cables (power cords and signal cables for example) separately. If they are close to one another, cross them over one another. If you route them in parallel, keep a minimum distance of 30 mm (1.18 in) between a power cord bundle and a signal cable bundle.

·     The cable management brackets and cable routing slots, inside or outside the rack, are smooth and do not have sharp edges or tips.

·     When you route cables through sharp sheet metal penetration points or along sharp edges of mechanical parts, use bushings or take any other action to protect the cables from being cut or abraded. The sheet metal penetration points must be smooth and fully rounded.

·     Use the correct type of ties to bind the cables. Do not bind cables with joined ties. The following types of ties are available: 100 × 2.5 mm (3.94 × 0.10 in), 150 × 3.6 mm (5.91 × 0.14 in), 300 × 3.6 mm (11.81 × 0.14 in), 530 × 9 mm (20.87 × 0.35 in), and 580 × 13 mm (22.83 × 0.51 in).

·     After binding the cables, cut the excess from the ties, leaving no sharp or angular tips. See Figure11-2.

Figure11-2 Cutting cable ties

 

·     When you bend cables, bind them as shown in Figure11-3. To avoid excessive stress causing cable core break, do not tie up the cables in the bending area.

Figure11-3 Binding cables where they must be bent

 

·     Route, bind, and attach excess cables for easy, safe maintenance activities and correct operations.

·     Do not tie power cords to slide rails.

·     When you connect a cable to an articulated part, for example, when you connect a grounding cable to a cabinet door, leave enough slack in cables and make sure they are not stressed from any movement of the part.

·     Cables must be protected at points where they might rub or come in contact with sharp edges or heated areas. Use high temperature cables near heat sources.

·     Securely fasten cables and take adequate measures to prevent loose connections.

Figure11-4 Securely fastening cables

(1) Flat washer	(2) Spring washer	(3) Nut

 

·     Fasten heavy or rigid power cords at the connectors to relief stress.

·     Do not use tapping screws to fasten the connecting terminals.

·     Bind together cables that are the same type and routed in the same direction.

Table11-1 lists the cable bundling specifications.

Table11-1 Tie-binding parameters

Cable bundle diameter (mm)	Space between bundles (mm)
10	80 to 150
10 to 30	150 to 200
30	200 to 300

 

·     Do not tie cables or bundles in a knot.

·     The metal parts of the crimped cold-pressed terminal blocks (such as circuit breaker) cannot protrude beyond the blocks.

Routing signal cables

The router provides cable management brackets along the left and right edges of the front panel and  cable management fingers at the top and bottom edges of each MPU and fabric module slot.

As a best practice, route signal cables along the nearest cable management fingers and cable management brackets.

Routing MPU cables

The MPUs are on the left of the front panel and the ports on each MPU are close to the  lower cable management finger. As a best practice, route MPU cables first along the lower cable management finger for the MPU slot and then through the left signal cable management bracket, as shown in Figure11-5.

Figure11-5 Routing MPU cables

 

Routing fabric module cables

As a best practice, route the fabric module cables along the nearest cable management fingers and cable management brackets.

For example, the router is installed with CR-19K-MSFU-20C fabric modules. As shown in Figure11-6, each CR-19K-MSFU-20C fabric module has 6 groups of ports, with 3 groups on the upper half of the module and 3 groups on the lower half. Use the cable management fingers and cable management brackets for the cables as follows:

·     Cables from the ports on the upper half of each module—Upper cable management finger for the slot.

·     Cables from the ports on the lower half of each module—Lower cable management finger for the slot.

·     Cables from the fabric modules in slots 22 to 24 (left slots)—Left cable management bracket.

·     Cables from the fabric modules in slots 25 to 27 (right slots)—Right cable management bracket.

Figure11-6 Routing fabric module cables (CR-19K-MSFU-20C)

 

Routing interface module cables

For easy maintenance, route cables from ports on the left part of an interface module along the left cable management bracket and cables from ports on the right part along the right cable management bracket.

Figure11-7 Routing interface module cables

 

Routing power cords

CAUTION: To protect cable adapters and converters, place them at the cabinet bottom. Do not place them at a location out of the cabinet and easy to reach.

 

IMPORTANT: For maintenance convenience, make sure the power cords do not block the power switch and fan trays on the rear panel.

 

Before routing power cords in the equipment room, consider the layout of the equipment room, including the locations of the power distribution box, AC power strips, and lighting protection box.

When AC power is used, connect the power cords to the PDUs on the cabinet, as shown in Figure11-8.

When DC power is used, router the power cords as shown in Figure11-9.

Figure11-8 Routing AC power cords

 

Figure11-9 Routing DC power cords