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This chapter describes the steps to take and the considerations you should keep in mind prior to installing the modules in an open rack. It also contains information that applies to an MGX 8850 installation in a Cisco closed rack. If the switch arrives in a Cisco closed rack, your initial concerns would be the cabinet grounding, power connections, and optional seismic stability plate. For specifications on the enclosure and power system, see "System Specifications."
The topics and section names in this chapter are:
Before proceeding with the installation, verify that all the ordered parts are present and in good condition. Store a record of the parts and serial numbers. If any parts are missing or damaged, contact your sales representative.
The reserved slots are 7 and 8 for the primary and redundant Processor Switching Modules (PXMs) and 15, 16, 31, and 32 for the Service Resource Modules (SRMs). These slot reservations reflect a fully redundant configuration for these cards. The maximum number of slots remaining for service modules is 24---less when the unit contains one or more double-height cards such as the Route Processor Module (RPM). Also, although not reserved, slots 9 and 10 should be the first choices for the location of one or more RPMs due to backplane wiring.
If you are considering any future card changes in which you replace a single-height card with a double-height card, place the single-height replacement candidates as far left in the card cage as possible. The reason is that single to double-height slot conversions must begin at the left and proceed to the right.
The slots on the top half of the card cage are suitable for the T3/E3 and OC-3 cards because the higher speed Cellbuses reside in the upper portion of the backplane. Place the service modules that operate at T1 or E1 rates in the lower half of the switch.
The site must satisfy the requirements in the following categories:
 | Caution If you move a Cisco-supplied cabinet, do not push it at its sides. Push at the front or back. |
To secure a Cisco-supplied cabinet, holes in the upper and lower corners accommodate 3/8" or 1/2" bolts. Also, an optional stability plate can be purchased with the Cisco cabinet. The stability plate is bolted to the floor, and the Cisco cabinet is bolted to the stability plate. Instructions for installing the stability plate appear in the section "Seismic Anchoring for a Cisco Closed Rack."
This section lists the requirements that relate to electrical power and grounding. These requirements cover installations at Central Office (CO) and Private Enterprise locations.
AC power must come from dedicated, AC branch circuits. Each circuit must be protected by a dedicated, two-pole circuit breaker. The circuit breakers at the source must have a rated current and trip delay greater than those of the MGX 8850 circuit breaker. Cisco recommends that the site have a 20A, 2-pole AC circuit breaker with a long trip-delay at each branch circuit.
The MGX 8850 nodes use a 20A, 2-pole circuit breaker for each AC input. The manufacturer of this circuit breaker is ETA, and the ETA part number for the circuit breaker is 8340-F120-P1P2-B2H020A.
For a DC-powered system, verify that its power comes from a dedicated DC branch circuit. This branch circuit must be protected by a dedicated circuit breaker. The circuit breaker must have a rated current and trip delay that is greater than those of the MGX 8850 circuit breaker. Cisco Systems recommends the site have a dedicated 70-Amp, 1-pole circuit breaker with a medium trip delay at each branch circuit.
DC-powered nodes use a 70-Amp, 1-pole circuit breaker with a short trip delay on each -48V input.
The MGX 8850 AC power requirement is a 220 VAC with a worst-case range of 180-240 VAC. Refer to ""System Specifications." An AC power source must be available within 6 feet (1.8 m) of the system and easily accessible. Before turning on the power, verify that the power supplied to the node comes from a dedicated branch circuit.
| Caution Consult Cisco engineering if the plans for MGX8850 AC power include a portable, uninterruptible power source (UPS). Cisco recommends a UPS with a low output impedance and the capacity to provide the necessary fault current to trip the protection devices. Do not use a UPS or any power source with a Ferro-Resonant transformer. |
The power receptacles to which the node connects must be of the grounding type. The grounding conductors that connect to the receptacles should connect to protective earth at the service equipment. For reference, Figure 3-1 shows the electrical relationship in the three-wire wall plug.
Cisco can provide AC power cords with the following plugs:
At the input of a DC-powered system, connect only a 48-VDC source that complies with the Safety Extra Low Voltage (SELV) requirements in EN 60950. Also, consult the local or national codes for conductor sizing for DC supply connections if necessary. Conductors must be suitable for 70 Amps. Wiring that is 6 AWG (10 square millimeters) is adequate.
To maintain the full EMI and EMC integrity of this equipment, it must be bonded to an integrated ground plane or an isolated ground plane network. The purpose is to mitigate the damaging effects to equipment from electrostatic discharge and lightning. Refer to the latest edition of ITU Recommendation K.27 or Bellcore GR-1089-CORE to ensure that the correct bonding and grounding procedures are followed. As recommended in these documents, a frame bonding connection is provided on the Cisco cabinet for rack-mounted systems. To see how to make a connection, see "Making the Frame Bonding (Ground) Connection" later in this chapter.
Except for the AC power supply module, every module in a rack-mount system uses the rack for grounding. Therefore, the rack must connect to protective earth ground.
A DC-powered node must have grounding conductors that connect at two separate locations:
The following telecommunications requirement may be relevant to a private network connected to the public switched networks in some international service areas: attach cabling such that the screws, bolts, or nuts that secure the cabling are tightened to the degree that removing it requires a tool.
This section describes how to install the Cisco cabinet with the optional stability plate for seismic anchoring. If you have no stability plate, go to "Enclosure and Card Installation."
To set up the Cisco cabinet with the stability plate, perform the following:
Step 1 Use the dimensions in Figure 3-2 to drill the holes for installing the stability plate.
Step 2 Remove the stability plate from the base of the Cisco cabinet. Save these nuts and bolts.
Step 3 With the user-provided anchoring bolts, attach the stability plate to the floor.
Step 4 Roll the Cisco cabinet over the stability plate as Figure 3-3 illustrates.
Step 5 Use the nuts and bolts from the shipping setup to secure the cabinet to the stability plate.
The Cisco-supplied cabinet comes with attached studs and hardware for securing a ground conductor to the studs at the top and bottom of the cabinet. These studs measure 1/4" by 20 threads per inch. Figure 3-4 shows the Cisco cabinet with the ground attachment studs in the upper and lower parts of the cabinet. A ground symbol on the Cisco rack indicates the points attachment.
Cisco recommends the following steps for attaching a ground conductor to the frame of a Cisco rack:
Step 1 Place an external, toothed star washer onto the stud.
Step 2 Place the connector terminating the grounding conductor closed-loop ring or two-hole compression fitting onto the stud.
Step 3 Place another external, toothed star washer or lock washer onto the stud.
Step 4 Screw a nut onto the threaded stud.
The MGX 8850 switch ships with a wrist strap for grounding the user and protecting the electronic components from electrostatic shock. The wrist strap kit consists of a strap, a coiled cord, and a clip for holding the strap.
Cisco recommends you install the base of the wrist strap cable on the left front flange of one of the units at a convenient height. Use a front mounting screw to secure the ring lug to the flange and front rail. The other end of the cord connects to the strap with a snap connector. Peel the back off the clip to expose the adhesive surface and attach to the front of the unit above the ring lug. Mount the clip sideways to allow the strap to be held in a position that will not interfere with the removal of the number card. Use the clip to store the strap.
Different Cisco products can reside in the same rack. If a multi-system rack configuration includes an MGX 8600-series switch, it should reside as the bottom unit.
Posted: Wed Jul 21 16:58:48 PDT 1999
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