WO2000018665A2 - Secure rack system for electrical equipment - Google Patents

Abstract

A rack unit (10) includes a plurality of racks (12) which are separated from each other with partitions (22). Each rack (12) has shelving for supporting equipment and it has stainless steel sides, tops (18), and bottoms for securing the equipment within the rack (12). Access to each rack (12) is restricted through a lockable door, such as a lock (20) controlled by a smart card and smart card reader. The racks (12) have ventilated walls (12), shelves, and tops (18) to allow circulation through the racks (12) from all sides. The tops (18) of the racks (12) include a fan for directing air upwardly through each rack (12) in order to cool the equipment stored within each rack (12). The cabling leading to and from equipment within each rack (12) is directed to at least one ladder rack (24) with each rack (12) only having access to its own cables and not to cables leading to or from neighboring racks (12).

Description

SECURE RACK SYSTEMS. METHODS. AND APPARATUS

FIELD OF THE INVENTION

The present invention relates generally to secure rack systems, methods, and

apparatus. More particularly, the invention relates to systems, methods, and apparatus for

securing equipment within racks and for securing cabling traveling to and from the

equipment.

BACKGROUND OF THE INVENTION

Many companies employ numerous pieces of electrical equipment to support their

operations, especially those operations involving telecommunications or computers.

Examples of this equipment include routers, modems, switches, repeaters, bridges,

servers, personal computers, storage devices, monitors, printers, and power management

equipment. This equipment can easily consume a considerable amount of space within a

facility and the cabling between pieces of equipment can quickly become unmanageable.

Facilities accordingly often store their equipment on one or more racks. Each rack

typically includes a number of shelves for storing equipment and provides access to both

the front and rear of the equipment. The racks come in industry standard dimensions of

19 inches wide, 24 inches deep, and 84 inches high, as well as in other less standard

dimensions.

A rack suffers from a disadvantage in that it often does not provide a facility with

a sufficient level of security since the racks usually permit free and unfettered access to

the equipment. The security that is available is designed to limit the people that have access to a room where the racks of equipment are located. Some additional security may

also be provided by placing the equipment in a cabinet. As with a rack, a cabinet has a

plurality of shelves for holding the equipment but also has a door to the front of the

cabinet that may be lockable. Access to the front of the equipment may therefore be

restricted only to those personnel having a key to the lock.

While the cabinet is more desirable than an open rack from the viewpoint of

limiting access, the cabinet is less desirable since it restricts ventilation. For many pieces

of equipment, adequate cooling is essential and a build-up of heat can rapidly interrupt

operations and cause equipment failure. The cabinets include one or more fans for

directing air over the equipment in order to cool the equipment. Because the cabinets

substantially enclose the equipment, the air flow over the equipment may be restricted,

thereby limiting the ability of the fans to adequately cool the equipment.

The conventional measures in a facility for securing its equipment are deficient.

The lockable door to the cabinet is certainly not an insurmountable barrier in view of the

Plexiglas door and simple lock. While the door and lock may discourage some

interference with the electrical equipment, the cabinet does not adequately protect the

cables connected to the equipment within the cabinet since these cables extend from the

rear of the cabinet and are often exposed. It is therefore frequently possible for someone

to interfere with a facility^'s operations simply through the access to these exposed cables.

This need for security is magnified when a company locates or relies on equipment

which is located on premises other than its own. For instance, telecommunication

companies can often derive by co-locating their equipment with other telecommunication

providers. An Internet service provider, for example, may have their equipment co- located with that of a local exchange carrier (LEC) or a data backbone provider to reduce

costs and to provide a more secure hook-up and hence secure network. A company,

however, has less control over who has access to its equipment when the control over

access to the equipment is shared between two or more companies. Consequently, a

company must assume a greater risk of inadvertent or even intentionally interference with

its equipment when the equipment is co-located with another company's equipment.

SUMMARY OF THE INVENTION

The present invention addresses the problems described above by providing secure

rack systems, methods, and apparatus. According to a preferred embodiment of the

invention, a rack unit includes a plurality of racks with each rack being separated from

neighboring racks with partitions. Each rack is formed of stainless steel and completely

encloses equipment contained on shelving within the rack. The walls, shelving, doors,

tops, and sides of each rack are preferably punched-out into the shape of a ventilated grid

having apertures for improving air flow through the racks. A fan is mounted on top of

each rack to force air upwardly through the rack, thereby cooling the electrical equipment

in the rack. The rack unit includes doors to the front of each rack as well as optional

doors at the rear of each rack. These doors are lockable and are preferably controlled by a

card entry system.

The rack unit according to the preferred embodiment includes at least 6 racks with

each rack having its own respective door, however, each rack may be partitioned into two

or more distinct racks. The cabling is secured within the rack so that someone who has

access to one rack cannot access or otherwise reach the cabling traveling to and from the other racks. The cabling may be routed within the rack in any one of a plurality of

different ways. In one example, the cabling from each rack is routed to a top section of

the rack unit and passes over a ladder rack dedicated for that rack. When the cables pass

over other racks, the cabling is inserted into a protective conduit. According to another

example, cabling from more than one rack travels downwardly to a shared ladder rack.

Access to the ladder rack is prevented by partitions that define cabling openings but

which prevent anyone from gaining access to the cabling on the ladder rack. From the

rack unit, the cabling may pass into protective conduits, be routed into an overhead

ceiling, or be routed into a raised floor.

Thus, with the rack unit according to the invention, access to any of the equipment

or any of the cabling is not possible unless the person is specifically authorized to have

such access. In other words, someone needs to have a key, smart card, or other suitable

device for unlocking a door to a rack in order to gain access to the equipment within the

rack. Although someone may have access to one rack, the person is denied the ability to

access equipment in other racks and the cabling for other racks. The rack unit secures the

equipment without sacrificing the ability to cool the equipment. The rack unit has

ventilated sides, tops, shelving, doors whereby air can flow through the racks in almost

any direction. To improve air flow, the fans mounted on top of each rack force air

upwardly in order to draw the heated air away from the equipment.

Accordingly, it is an object of the present invention to provide secure rack

systems, methods, and apparatus for protecting electrical equipment.

It is another object of the present invention to provide secure rack systems,

methods, and apparatus for protecting equipment while providing sufficient ventilation for the equipment.

It is a further object of the present invention to provide secure rack systems,

methods, and apparatus for protecting cabling leading to and from equipment within

racks.

It is yet another object of the present invention to provide secure rack systems,

methods, and apparatus that enable equipment to be securely co-located with other

equipment.

It is still a further object of the present invention to provide secure rack systems,

methods, and apparatus for providing secure connections to other equipment.

It is still another object of the present invention to provide secure rack systems,

methods, and apparatus for controlling access to equipment within racks.

Other objects, features, and advantages of the present invention will become

apparent with respect to the remainder of this document.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part of the

specification, illustrate preferred embodiments of the present invention and. together with

the description, disclose the principles of the invention. In the drawings:

Figure 1 is a diagram of a rack unit according to a first embodiment of the

invention;

Figure 2 is a front elevation view of a wing forming part of a rack unit according

to a second embodiment of the invention;

Figure 3 are partial views of doors for the rack unit of Figure 2;

Figure 4 is a partial top view of one wing of the rack unit of Figure 2;

Figure 5 is side elevation view of one wing of the rack unit of Figure 2;

Figure 6 is a partial view of a wing having a ladder rack for the rack unit of Figure

2;

Figure 7 is a diagram of a rack unit having front access;

Figure 8 is a diagram of a rack unit having both front and rear access;

Figures 9A and 9B are plan views of a door and associated hinge for the rack unit

of Figure 2;

Figures 10A and 10B are more detailed views of the door and associated hinge for

the rack unit of Figure 2;

Figure 11 is an enlarged view of the door and associated lock for the rack unit of

Figure 2; and

Figure 12 is a sketch of the rack unit according to a further embodiment of the

invention. DETAILED DESCRIPTION

Reference will now be made in detail to preferred embodiments of the invention,

non-limiting examples of which are illustrated in the accompanying drawings.

A rack unit 10 according to a preferred embodiment is shown in Figure 1. The

rack unit 10 includes a plurality of racks 12 separated from each other by partitions. The

racks 12 may be formed in various sizes, such as a full length rack 12 A, a two-thirds

length rack 12B, or a one-third length rack 12C. The rack unit 10. in this example of the

invention, comprises two wings 14 of racks joined together with a wall 16. A cabling

section 18 is formed on top of the racks 12 in each wing 14 and provide secure space for

running cables to and from equipment stored within the racks 12.

The racks 12 preferably are formed in industry standard measurements, such as 19

inches wide, 24 inches deep, and up to 84 inches high. In the example shown in Figure 1 ,

the racks 12A have a height of 84 inches, the racks 12B have a height of 56 inches, and

the racks 12C have a height of 28 inches. It should be understood that these dimensions

are only examples of dimensions for the racks 12 and the rack unit 10 may have racks 12

having other dimensions. For example, the racks 12 may be limited to full-length racks

12A and to half-length racks 12. Each rack has a number of shelves with these shelves

being adjustable within the rack. Each rack 12 is separated from others by partitions and

the racks 12 at least have doors for providing access to the front of the equipment and

may additionally have doors at the rear for providing access to the back of the equipment

in the rack 12. Each of the doors to a rack 12 includes a lock 20 for restricting access to

equipment stored within each rack 12. The cabling for the equipment within the racks is securely routed within the rack

unit 10. For the full-length racks 12 A. the cabling is routed upwardly to a ladder rack 24.

From within one rack 12, a person is prevented from being able to access cabling from

other racks due to partitions 22 and protective conduits 26. The partitions 22 block access

to neighboring ladder racks 24 and the conduits 26 protect the cabling as it travels above

other racks 12. For the racks 12 that are stacked on top of each other, such as rack units

12B and 12C, the cabling is inserted into protective conduit as it passes through other

racks 12 before reaching a ladder rack 24. The use of a plurality of ladder racks 24,

partitions 22. and conduits 26 is just one example of how the cabling may be protected

and, as will become apparent from the description below, the cabling may be protected in

other ways.

The top sections 18 of the rack unit 10 are shown in partial cut-away views with

one wing 14 being shown with the partitions 22 and the other wing 14 illustrating the

conduits 26 and ladder racks 24. In this example, each top section 18 includes at least one

ladder rack 24 for routing cables to and from equipment within each rack 12. To prevent

someone having access to one rack 12 from being able access cables running to and from

a neighboring rack 12, the cables pass through the conduits 26 as they travel through

neighboring racks 12. The rack unit 10 further includes the partitions 22 for preventing

one column of racks 12 from being able to access neighboring columns of racks 12.

These partitions 22 include appropriate apertures for the running of the conduits 26. In

this example, the cables are routed through the ladder racks 24 and into conduits 26 to one

end of the rack unit 10. The secure routing of the cables outside of the rack unit 10 will

be described in more detail below. The rack unit 10 shown in Figure 1 includes the wall 16 having a door 28 and lock

20. Additional security measures may be provided through the door 28 and lock 20

depending upon the particular application of the rack unit 10. For instance, the rack unit

10 may be positioned against a wall so that someone must pass through the door 28 in

wall 16 in order to gain access to the equipment within the racks 12. The lock 20 on the

door 28 therefore provides additional security to the equipment and cabling within racks

12.

According to another aspect of the invention, the rack unit 10 may have a

completely enclosed backbone section 17, as indicated by the sets of dashed lines 19 in

Figure 1. The backbone section 17 is accessible only through the door 28 and. according

to this example, receives all cables from the equipment. Thus, the cabling traveling to

and from the equipment passes through the backbone section 17 before being routed to

another secure area. The backbone section 17 may include equipment of its own, such as

a back-up power supply, fans or other cooling equipment, monitoring equipment such as

smoke and fire detectors, and fire extinguishing equipment. The backbone section 17 is

preferably ventilated, especially if it contains electrical equipment of its own. so as to

permit an air flow through the section 17. In this application, the cabling passes through

the top section 18, or through a bottom section, and exits into the backbone section 17.

From the backbone section 17. the cabling passes through conduits or through other

secure areas to its destinations.

An example of another rack unit 10 is shown in Figures 2 to 11. In this example,

the top section 18 of each wing 14 includes a single ladder rack 24 for all racks 12 within

that wing 14. Each rack 12 is joined to the top section 18 through a cabling opening that permits the routing of cables between the ladder rack 24 and equipment within the racks

12 but which prevents anyone from reaching or otherwise accessing cables on the ladder

rack 24. The top section 18 may have its own door and lock to permit only those with

oversight of the rack unit 10 from accessing the ladder rack 24.

The rack unit 10 shown in Figures 2 to 11 is accompanied with exemplary

dimensions for the rack unit 10. The invention, however, is not limited to a rack unit

having these particular dimensions but instead may have different dimensions. A front

elevation of one wing 14 of the rack unit 10 is shown in Figure 2. As shown in the

Figure, the doors to each rack 12 are fabricated to have a frame 32 surrounding a grid 31

having a plurality of apertures 31A. The frame 32 and elements 31B of the grid 31 are

formed of a tamper resistant material, such as stainless steel, and preferably have the

apertures 31 to assist in the free flow of air through the racks 12. The doors, as well as all

other parts of the rack unit 10, are not limited to any particular pattern of elements 3 IB

and apertures 31A but instead encompasses all ventilated designs.

With reference to Figure 3, examples of some suitable dimensions for the doors for

racks 12 A, 12B. and 12C are shown. Each door preferably includes the solid metal frame

32 within which is contained the ventilation grid 31 having apertures 31 A. The rack unit

10 has a plurality of hinges equally spaced for each rack 12. As will become more

apparent from the description below, this spacing of hinges allows a door for a rack 12A

to be replaced with two doors for racks 12B and 12C or three doors for three racks 12C.

A top view of one wing 14 of the rack unit 10 is shown in Figure 4. Figure 4 is

only a partial view of the top of the rack unit 10 with the ladder rack 24 not being shown.

The racks 12 include cable openings 33 for routing the cables to and from the ladder rack 24 contained within the top section 18. These cable openings 33 allow the cabling to pass

between the ladder rack 24 and the equipment in the respective racks 12 but prevent

anyone from otherwise being able to access the cabling on the ladder rack 24. The top of

each unit 14 as depicted in Figure 4. is fabricated of stainless steel having a frame

surrounding a ventilation grid pattern.

A side elevation view of a unit 14 of the rack unit 10 is shown in Figure 5. The

sides are also formed to have a ventilation grid and have a solid metal frame around the

outside of this grid. Figure 5 also depicts the ladder rack 24 that extends across the top of

the wing 14 of the rack unit 10.

Figure 6 depicts a top view of a wing 14 of the rack unit 10 with the ladder rack

24. In this example, a single ladder rack 24 extends across the entire top of the wing 14.

The top of each rack 12 is formed with openings 33 that lead to this top space containing

the ladder rack 24. Each rack 12, however, is partitioned from the other racks whereby

those having access to one rack cannot access or otherwise reach the cables leading to or

from other racks 12.

The rack unit 10 may be formed with doors on only the front side or with doors on

both the front and rear sides of each rack 12. For instance, as shown in Figure 7, a wing

14 of the rack unit 10 may have doors 35 that are only located on one side of each rack

12. Alternatively, as shown in Figure 8, each rack 12 may include both front and rear

doors 37 thereby providing access to both the front and rear of equipment contained

within the racks 12. Although not shown, the rack unit 10 may be fabricated so that some

of the racks 12 have only front doors 35 whereas other racks 12 have both front and rear

doors 37. A more detailed diagram of a door with associated hinge 39 is shown in Figure

9 A. The spacing between each door 35 or 37 and the stationary framing or door jam of

the rack unit 10 is preferably so as to provide a close fit when the door 35 or 37 is closed.

In this example, the stationary framing or door jam comprises tubular metal cabinet

support posts, although other secure structures may be used in the rack unit 10. Dividing

partitions 41 separate one rack 12 from neighboring racks 12 and are also preferably

comprised of a solid frame around a ventilation grid. Figure 9B illustrates an enlarged

view of the door and hinge 39.

A more detailed diagram of a hinge for a door is shown in Figure 10A. The hinge

39 preferably includes a pin 43 secured to the stationary framing or door jam of the rack

unit 10. The door includes a member 45 that fits over the pin 43 when the door is lowered

into position. The member 45 may be integral with the door frame 32 or may be welded

into position. The invention is not limited to this particular hinge 39 but may be

fabricated with other types of secure hinges. An enlarged view of the hinge 39 is shown

in Figure 10B. The hinges 39 are preferably equally spaced along the length of each door

so as to provide even support for the weight of the door.

Figure 11 depicts one example of a lock 20 according to the invention. In this

example, the lock 20 comprises a key-lock having a latch 51 for locking the door and has

a keyhole 53 for receiving a key. In an alternate preferred embodiment of the invention,

the locks 20 are not key locks but rather comprise locks controlled by cards, such as smart

cards. The locks 20 include card readers for receiving a smart card or other suitable card.

Each card reader and associated lock 20 opens only when the person assigned to the card

is authorized to enter the rack 12. A single person may have authority to enter a rack 12 or, alternatively, only a set of approved people may have access. The card readers and

locks 20 may provide for different levels of security, such as a lower level for allowing

access to a rack 12 and increased level of security for allowing access to the backbone

section 17. The card readers and lock 20, in addition to controlling access, also monitor

and log access to the racks 12. Thus, records are maintained as to who and when each

rack 12 was accessed.

The card reader and lock 20 may employ any suitable lock, such as a magnetic

lock or an electric strike lock. The electric strike lock is preferred over the magnetic lock

since equipment within the racks 12 may be sensitive to the magnetic fields. The electric

strike lock preferably is of the "fail" design so that power is required to unlock the door.

When the card reader receives a card, the card reader determines whether access to a rack

12 should be permitted for the person associated with that card. The card reader

communicates with a card control system that controls exactly who has access.

Communications between the card readers and card control system and even between the

cards and card readers are secure, incorporating appropriate encryption and

authentication. If a person is supposed to have access, then the card reader provides

power to the lock, such as the electric strike lock, to unlock the door. When power is not

provided to the card reader, such as during a power failure or during attempts to bypass

the card reader, since power is not provided to the lock the door remains locked. One

example of a card entry control system is provided by Cylink of Sunnyvale, California.

The smart cards may comprise the Cylink PrivateCard™ and the locks 20 include the

Cylink PrivateSave™ smart card reader.

The rack unit 10 may employ additional locks 20 as well as other types of "locks." As discussed above, the rack unit 10 may have separate locks for allowing access to

ladder racks 24 and has the lock 20 on the door 28. The card control system preferably

also controls other doors that control access to rooms within which the rack unit 10 or

groups of rack units 10 are located. The locks may also include any combination of

keypad locks, voice-verified locks, fingerprint scanning locks, or retina scanning locks.

As discussed above, the cabling is protected within each rack 12 since it cannot be

accessed or otherwise reached from within the other racks 12 or from outside the rack unit

10. The cabling is also secure when it leaves the rack unit 10 to join other equipment or

cabling. The place where the cabling exits the rack unit 10 varies according to the

particular application of the invention and the invention is accordingly not limited to any

particular exit location. The exact location or manner in which the cabling is routed

outside of the rack unit 10 depends upon many factors, such as the position of the rack

unit 10 relative to walls or ceiling in a room and whether the room has a drop-down

ceiling or a raised floor. The rack unit 10, for instance, may be positioned so that the ends

of each wing 14 abut against a wall. In this application, the cabling can exit the rack unit

10 through the top section 18, or through a bottom section, and then can pass through the

wall into an area of heightened security.

In other applications, the cabling exiting the individual racks 12 passes through

portions of a drop ceiling or through portions of a raised floor. In these applications, the

cabling passes through the top section 18 and then enters a protective conduit that is

routed into the ceiling. On the other hand, cabling may instead pass through the bottom

section and into a conduit that descends beneath the raised floor. Protective conduits may

not be necessary if the cabling can be routed through the ceiling, floor, or wall without exposing the cabling. Also, the cabling need not exit from the top or bottom of the rack

unit 10 but may alternatively pass down the side of the wing 14 or exit through a side of

the rack unit 10.

An illustration of a rack unit 10 according to another aspect of the invention is

shown in Figure 12. As depicted in this figure, the rack unit 10 includes a plurality of

individual racks 12. In this example, the rack unit 10 includes full-length racks 12A

providing access only to the front of the equipment, which corresponds to an interior of

the U-shaped rack unit 10. The rack unit 10 also includes the top section 18 for enclosing

at least one ladder rack. The rack unit 10 includes two wings 14 of racks 12 with these

two wings 14 being joined by the wall 16. The sides and tops of the rack unit 10 is

ventilated so as to improve air flow through the racks 12.

The forgoing description of the preferred embodiments of the invention has been

presented only for the purpose of illustration and description and is not intended to be

exhaustive or to limit the invention to the precise forms disclosed. Many modifications

and variations are possible in light of the above teaching.

According to another aspect of the invention, the cabling leading to and from each

rack is preferably routed underneath each rack 12 rather than to the top of each rack 12.

The heat generated by equipment within the racks 12 travels upwardly and the cabling is

placed underneath the racks 12 to advantageously isolate the cabling from this heat. The

rack unit 10 therefore includes a bottom section for containing the cabling and has at least

one ladder rack contained within this bottom section. Access to the cabling in

neighboring racks is prevented with partitions separating the racks from each other. This bottom section has ventilated sides to permit air flow but is formed of a sturdy material,

such as stainless steel.

To assist in the removal of heat within the racks, a fan is mounted within the top

section 18. In the preferred embodiment, a fan is mounted above each rack and forces a

flow of air upwardly through the rack 12. This fan is preferably a rack-mounted fan, such

as one from Hoffman Engineering of Stamford Connecticut.

The embodiments were chosen and described in order to explain the principles of

the invention and their practical application so as to enable others skilled in the art to

utilize the invention and various embodiments and with various modifications as are

suited to the particular use contemplated.

Claims

CLAIMSWhat is claimed:

1. A rack unit for securing electrical equipment, comprising:

a plurality of shelves for holding the electrical equipment;

a back wall for preventing access to the electrical equipment from a rear of the

equipment;

a front wall for preventing access to the electrical equipment from a front of the

electrical equipment;

side walls for preventing access to the electrical equipment from either side of the

electrical equipment;

a door secured to the front wall for permitting access to the electrical equipment;

and

a lock associated with the door for selectively permitting access to the electrical

equipment through the door;

a top section for preventing access to the electrical equipment from a top;

wherein at least one of the back wall, front wall, door, side walls, and top section

is ventilated for allowing a flow of air through the rack unit.

2. The rack unit as set forth in claim 1. further comprising a fan mounted in

the top section for circulating air throughout the rack unit.

3. The rack unit as set forth in claim 1 , further comprising a second door for providing access to the rear of the rack unit.

4. The rack unit as set forth in claim 1 , further comprising a card entry system

for opening the lock.

5. The rack unit as set forth in claim 1, further comprising a partition for

separating the rack unit into at least two units with each of the units being associated with

a door and a lock.

6. The rack as set forth in claim 5, further comprising a conduit for containing

cables associated with one unit and for preventing access to the cables from within the

other unit.

7. The rack as set forth in claim 6, wherein the conduit travels through the top

section.

8. The rack as set forth in claim 1, further comprising a backbone section for

housing a back-up power supply.

9. A rack unit for storing electrical equipment, comprising:

a plurality of racks;

each rack comprising:

a partition for separating each rack from a neighboring rack; at least one door and a lock associated with the door; and

walls, shelving, a door, a top, and sides to prevent unauthorized

access to the electrical equipment;

the rack unit having a cabling opening for routing cable to and from

the equipment;

wherein the cable within each rack is secured to prevent access to the cable

from within another rack.

10. The rack unit according to claim 9, wherein the racks have adjustable

shelves.

11. The rack unit according to claim 9, further comprising a fan mounted on

top of each rack for circulating air through each rack.

12. The rack unit according to claim 9. wherein each rack includes a conduit

for holding cables and a ladder rack for the routing of cables within each rack.

13. The rack unit according to claim 9, wherein the door comprises a solid

metal frame and a plurality of hinges spaced to provide support for the door.

14. The rack unit according to claim 13, wherein each door hinge includes a

pin secured to the door frame, and the door includes a mounting member that fits over the

pin when the door is lowered into position.

15. The rack unit according to claim 9, wherein the racks are grouped into two

wings of racks joined to each other with a wall.

16. The rack unit as set forth in claim 9, further comprising a second door and a

second lock, the second door being located in the wall and the second lock being

associated with the second door.

17. The rack unit according to claim 9, further comprising a backbone and a

second door for allowing access to the backbone, the backbone section for receiving

cables from equipment in the racks.

18. The rack unit according to claim 17, wherein the backbone includes cooling

equipment.

19. The rack unit according to claim 17. wherein the backbone includes

environment monitoring equipment.

20. The rack unit according to claim 17, wherein the backbone includes fire

extinguishing equipment.