Installing the Switch Router

Site Planning

Site Power

Rack-Mounting the Switch Router

Gigabit Interface Converter

Patch Cord

Patch Cord Installation

Differential Mode Delay

GBIC Installation and Removal

GBIC Installation

GBIC Removal

Connecting to the Gigabit Ethernet Ports

Connecting Power to the Switch Router

Installing the Switch Router

This chapter describes how to prepare your site for installation and how to rack-mount the Catalyst 2948G-L3 switch router. It also provides Gigabit Interface Converter (GBIC) information and instructions for connecting power to the switch router. For first-time installations, perform the procedures in the following sections in the order listed.

Warning
Before you install, operate, or service the system, read the Site Preparation and Safety Guide. This guide contains important safety information you should know before working with the system.

Site Planning

Planning the proper location and layout of your equipment rack or wiring closet is essential for successful switch router operation. Equipment placed too close together or in an inadequately ventilated area can cause system overtemperature conditions. In addition, poor equipment placement can make system panels inaccessible and difficult to maintain.

The Catalyst 2948G-L3 switch router operates as a standalone switch router mounted in a rack in a secure wiring closet. If the airflow is blocked or restricted, or if the intake air is too w arm, an overtemperature condition can occur. The switch router's environmental monitor can then shut down the system to protect the components.

To ensure normal operation and avoid unnecessary maintenance, plan your site configuration and prepare your site before installation. For a description of the environmental monitor, see the "Environmental Monitoring of the Power Supplies" section.

Table A-1 lists the operating and nonoperating environmental site requirements for the switch router. The environmental ranges are those within which the system continues to operate; however, a measurement that approaches the minimum or maximum of a range indicates a potential problem. You can maintain normal operation by anticipating and correcting environmental anomalies before they exceed the maximum operating range.

Site Power

This section provides site power recommendations for the Catalyst 2948G-L3 switch router. Ensure that you verify the site power for the type of device you are installing. Ensure that these conditions are met when preparing your site for device installation:

Connect each power supply to separate wiring on a dedicated circuit; provide each power supply with its own branch circuit connection with sufficient overcurrent protection and direct grounding to the branch circuit.

Verify that the total maximum load on each AC circuit supplying the power supplies is within the current ratings of the wiring and breakers to prevent a loss of input power.

Note The

redundant power option provides a second power supply to ensure that power to the switch router continues if one power supply fails or input power on one line fails. The redundant power supply provides this second feature only if the power supplies are connected to separate input lines.

Caution The total maximum load on each input power circuit must be within the rating of the wiring and breaker. An overload of input power can result if this requirement is not met.

Power requirements are useful for planning the power distribution system needed to support the switch router. Heat dissipation is an important consideration for sizing the air-conditioning requirements for an installation. See Table A-1 for power and heat ratings for the Catalyst 2948G-L3 switch router.

Rack-Mounting the Switch Router

Before installing the Catalyst 2948G-L3 switch router in a rack, read the Site Preparation and Safety Guide to familiarize yourself with proper site and environmental conditions. Failure to read and follow these guidelines could lead to an unsuccessful installation and possible damage to the switch router and components.

The following tools and equipment are required to install the switch router in a rack:

A 3/16-inch flat-blade screwdriver
Four 12-24 x 3/4-inch screws
A disposable electrostatic discharge (ESD) grounding strap or ESD-preventive strap
A rack-mount kit
A tape measure and level

Warning Unplug power cords before you work on a system that does not have an
on/off switch.

To install the Catalyst 2948G-L3 switch router in a rack, follow these steps:

Step 1 Prepare for installation as follows:

(a) Place the switch router on the floor or on a sturdy table as close as possible to the rack. Leave enough clearance so that you can move around the switch router.

(b) Use a tape measure to measure the depth of the rack. Measure from the outside of the front mounting posts to the outside of the rear mounting strip. The depth must be at least 18 inches (48.9 cm) but not greater than 32 inches (81.3 cm).

(c) Measure the space between the inner edges of the left front and right front mounting posts to ensure that it is 17.75 inches (45.72 cm) wide. (The switch router is 17.3 inches [44 cm] wide and must fit between the mounting posts.)

Note

Step 2 Remove the four (two on each side) M3 screws that are adjacent to the vent openings on the sides of the chassis. (See Figure 2-1.)

Figure 2-1: Removing the M3 Screws

Step 3 Attach the left and right L brackets using the eight (four on each side) flat-head Phillips screws provided in the rack-mount kit. (See Figure 2-2.)

Figure 2-2: Attaching the L Brackets to the Catalyst 2948G-L3

Step 4 Install the switch router in the rack as follows:

(a) Insert the rear of the switch router between the mounting posts (see Figure 2-3).

Figure 2-3: Installing the Catalyst 2948G-L3 in the Rack

(b) Align the mounting holes in the L bracket with the mounting holes in the equipment rack.

(c) Secure the switch router using four (two per side) 12-24 x 3/4-inch screws through the elongated holes in the L bracket and into the threaded holes in the mounting post.

The Catalyst 2948G-L3 switch router powers up when you connect the power cord. See the "Connecting Power to the Switch Router" section.

Gigabit Interface Converter

A GBIC is a hot-swappable input/output device that plugs into the Gigabit Ethernet port, linking the switch router with the fiber-optic network (see Figure 2-4). The following GBIC media types are supported:

1000BaseSX
1000BaseLX/LH
1000BaseZX

Figure 2-4: Gigabit Interface Converter

Note Because of interoperability issues, Cisco does not support GBICs purchased from third-party vendors.

Note See Table A-4 for GBIC port specifications.

Patch Cord

When using the LX/LH GBIC with 62.5-micron diameter multimode fiber (MMF), you must install a mode-conditioning patch cord (Cisco product no. CAB-GELX-625 or equivalent) between the GBIC and the MMF cable on both the transmit and receive ends of the link. The patch cord is required for link distances greater than 984 feet (300 meters).

The patch cord must comply with IEEE standards. The IEEE found that link distances did not meet with certain types of fiber-optic cable because of a problem in the center of some fiber-optic cable cores. The solution is to launch light from the laser at a precise offset from the center by using the patch cord. At the output of the patch cord, the LX/LH GBIC is compliant with the IEEE 802.3z standard for 1000BaseLX. For a detailed description of this problem, refer to the "Differential Mode Delay" section.

Note Cisco Gigabit Ethernet products have been tested and evaluated to comply with the standards listed in "Specifications." Equivalent cables should also meet these standards.

Patch Cord Installation

Plug the end of the patch cord labeled "To equipment" into the GBIC (see Figure 2-5). Plug the end labeled "To cable plant" into the patch panel. The patch cord is 9.84 feet (3 meters) long and has duplex SC-type male connectors at each end.

Figure 2-5: Installing the Patch Cord

Differential Mode Delay

When an unconditioned laser source (LX/LH GBIC) designed for operation on single-mode fiber (SMF) cable is directly coupled to an MMF cable, differential mode delay (DMD) can occur. DMD can degrade the modal bandwidth of the fiber-optic cable causing a decrease in the link span (the distance between the transmitter and the receiver) that can be reliably supported.

The Gigabit Ethernet specification (IEEE 802.3z) outlines parameters for Ethernet communications at a gigabits per second rate. The specification offers a higher speed version of Ethernet for backbone and server connectivity using existing deployed MMF cable. To accomplish this, the specification defines the use of laser-based optical components to propagate data over MMF cable.

Lasers function at the baud rates and longer distances required for Gigabit Ethernet. The IEEE 802.3z Gigabit Ethernet Task Force has identified the DMD condition that occurs in certain circumstances with particular combinations of lasers and MMF cable. The resulting characteristics create an additional element of "jitter" that limits the reach of Gigabit Ethernet over MMF cable.

With DMD, a single laser light pulse excites a few modes equally within an MMF cable. These modes, or light pathways, then follow two or more different paths. These paths may be of different lengths and have different transmission delays as the light travels through the cable. With DMD, a distinct pulse propagating down the cable no longer remains a distinct pulse or, in extreme cases, can become two independent pulses. Strings of pulses tend to interfere with each other making it difficult to recover data in a reliable fashion.

DMD does not occur in all deployed fibers. It occurs with certain combinations of worst-case fibers and worst-case transceivers. Gigabit Ethernet is the first technology to experience this problem because of its very high baud rate and its long MMF cable lengths. SMF cable and copper cable are not affected by DMD.

MMF cable has only been tested for use with LED sources. LEDs create a condition within a fiber-optic cable referred to as an overfilled launch condition. The overfilled launch condition describes the way LED transmitters couple light into the fiber-optic cable in a broad spread of modes. Similar to a light bulb radiating light into a dark room, the generated light shines in multiple directions that "overfill" the existing cable space and "excites" a large number of modes (see Figure 2-6).

Figure 2-6: LED Transmission Compared to Laser Transmission

Lasers launch light in a more concentrated fashion. Typically, a laser transmitter couples light into only a fraction of the existing modes or optical pathways in the fiber-optic cable (see Figure 2-6).

The solution to DMD is to condition the laser light launched from the source (transmitter) so it spreads the light evenly across the diameter of the fiber-optic cable making the launch look more like an LED source to the cable. The objective is to scramble the modes of light to distribute the power more equally in all modes. This prevents the light from being concentrated in just a few modes. This is in contrast to an unconditioned launch, which, in the worst case, might concentrate all of its light in the center of the fiber-optic cable, thereby exciting only two or more modes equally.

A significant variation in the amount of DMD is produced from one MMF cable to the next. No reasonable test can be performed to survey an installed cable plant to assess the effect of DMD. Therefore, you must use the mode-conditioning patch cords for all LX/LH GBICs using MMF when the link span exceeds 984 feet (300 meters). For link spans less than 300 meters, you can omit the patch cord .

GBIC Installation and Removal

This section describes how to install, maintain, and remove GBICs. Read the installation information in this section before you install a GBIC.

Note If an LX/LH GBIC designed for operation on single-mode fiber (SMF) cable is directly coupled to a multimode fiber (MMF) cable, DMD can occur. See the "Differential Mode Delay" section.

Caution Unnecessary removal or insertion of a GBIC could lead to premature failure of the GBIC. A GBIC has a lifetime of 100 to 500 removals or insertions.

Follow these GBIC care and handling guidelines:

GBICs are static sensitive. To prevent ESD damage, follow your normal board and component handling procedures.
GBICs are dust sensitive. When the GBIC is stored or when a fiber-optic cable is not plugged in, always keep plugs in the GBIC optical bores.
The most common source of contaminants in the optical bores is debris picked up on the ferrules of the optical connectors. Use an alcohol swab or Kim-Wipe to clean the ferrules of the optical connector.

GBIC Installation

A module can be shipped with or without GBICs installed.

Caution When removing or inserting a GBIC, always wear an ESD wrist strap connected to the ESD wrist strap connector.

Note GBICs are online swappable.

To install a GBIC, follow these steps:

Step 1 If the port you are installing the GBIC on is not in the administratively down state, enter the shutdown command.

Step 2 Remove the GBIC from its protective packaging.

Step 3 Verify that the GBIC is the correct type for your network by checking the part number. The number indicates whether it is 1000BaseSX, 1000BaseLX/LH, or 1000BaseZX.

Step 4 Grip the sides of the GBIC with your thumb and forefinger; insert the GBIC into the slot on the front of the module (see Figure 2-7).

Note GBICs are keyed to prevent incorrect slot insertion.

Figure 2-7: Installing a GBIC

Step 5 Slide the GBIC into the slot until you hear a click. The click indicates the GBIC is locked into the slot.

Step 6 Remove the plugs from the GBIC when you are ready to attach the fiber-optic cable. Save the plugs for future use.

Step 7 If you entered the shutdown command in Step 1, enter the no shutdown command after attaching the fiber-optic cables.

Caution Do not remove the plugs from the GBIC optical bores or the fiber-optic cable until you are ready to connect the cable. The plugs protect the GBIC optical bores and cable from contamination.

GBIC Removal

Note If you are removing the GBIC from an online switch router, enter the show interface command to verify the type of GBIC that is installed.

To remove a GBIC, follow these steps:

Step 1 If the port you are removing the GBIC from is not in the administratively down state, enter the shutdown command.

Step 2 Disconnect the fiber-optic cable from the GBIC SC-type connector.

Step 3 Release the GBIC from the slot by simultaneously squeezing the plastic tabs (one on each side of the GBIC).

Step 4 Slide the GBIC out of the slot.

Step 5 Install the plugs in the GBIC optical bores, and place the GBIC in protective packaging.

Step 6 If you entered the shutdown command in Step 1, enter the no shutdown command after attaching the fiber-optic cables.

Connecting to the Gigabit Ethernet Ports

To connect to the Gigabit Ethernet ports, follow these steps:

Step 1 Remove the plugs from the GBIC optical bores; store them for future use.

Step 2 Remove the plugs from the SC-type connector on the fiber-optic cable. Insert the connector into the GBIC (see Figure 2-8).

Note When you plug the SC-type connector into the GBIC, make sure that both the Tx and Rx fiber-optic cables are fully inserted into the SC-type connector.

Note If you are using the LX/LH GBIC with MMF, you must install a patch cord between the GBIC and the MMF cable. See the "Patch Cord" section.

Figure 2-8: SC-Type Connector

Connecting Power to the Switch Router

To connect power to the Catalyst 2948G-L3 switch router, follow these steps.

Step 1 Ensure that all site power and grounding requirements described in the Site Preparation and Safety Guide have been met prior to connecting the power supply to a power source.

Step 2 Plug the power cord into the switch router.

Step 3 Connect the other end of the power cord to an AC-input power supply.

Step 4 Verify power supply operation by checking the front panel power supply LEDs. See Table 1-1.

See "Troubleshooting the Switch Router," if the LEDs indicate a power or other switch router problem.

Caution Multiple power connections may be provided. To de-energize the switch router, disconnect the power cord and RPS cable.

Table of Contents

Installing the Switch Router

Patch Cord