Table of Contents

Hardware Configuration

Setting Jumpers and Switches on Access Cards
Setting LSAC Interface Jumpers
Setting CEMAC Interface Jumpers
Settings for Use with a Fantail
Settings for Use without a Fantail
Turning Off the Transmit Laser on the OC3AC
Setting Jumpers and Switches on Fantails
Setting Ground Jumpers on the E1 Fantail
Configuring X.21 Ports as DTE or DCE
Component Configuration
NPs, Switch Cards, Line Cards, Disks, and Power Trays
Access Cards and Console/Modem Assemblies
Blowers

Hardware Configuration

This chapter shows how to set jumpers and switches in LightStream 2020 hardware, and explains how many of each major hardware component---NPs, switch cards, line cards, and power supplies---can coexist in a LightStream 2020 enterprise ATM switch.

Caution Before removing any components from the chassis, read the "Safety Instructions" section in the chapter entitled "Hardware Troubleshooting". If you handle components without taking proper ESD precautions, you can damage the system.

Setting Jumpers and Switches on Access Cards

This section explains how to set jumpers and switches on I/O access cards. It includes these procedures:

• "Setting LSAC Interface Jumpers"
  

• "Setting CEMAC Interface Jumpers"
  

• "Turning Off the Transmit Laser on the OC3AC"
  

Setting LSAC Interface Jumpers

This section describes the user-settable jumpers on the low-speed access card (LSAC) and shows how to set them. The jumpers allow you to select one of two interface types:

• V.35
  

• RS-449/X.21
  (If you select this option, the fantail determines whether the ports are RS-449 or X.21.)
  

These jumpers are set for you in the factory based on the configuration specified in your system order, so you should not have to change the jumpers unless you change your configuration.

Figure 4-1 shows the location of the 16 sets of interface jumpers on the card, and illustrates how to set them. For V.35, put jumpers on the left and center pins. For RS-449 and X.21, put jumpers on the right and center pins. (The settings are indicated on the card, as shown.)

Each LSAC serves up to eight I/O ports. If you want all eight ports to use the same interface, set all the jumpers the same way. If you prefer, you can set the LSAC to give you four ports of one type and four of another (four V.35 and four X.21, for example). You'll need one fantail of each type.

The interface jumpers are labelled E1 through E8 and E11 through E18. (E9 and E10 are not interface jumpers and are not located near the interface jumpers on the card.) The interface jumpers can be divided functionally into two groups:

• The top eight jumpers, E1 through E8, affect ports 4 through 7, which are served by the top connector on the rear edge of the card.
  

• The bottom eight jumpers, E11 through E18, affect ports 0 through 3, which are served by the bottom connector on the rear edge of the card.
  

(The two connectors on the rear edge of the card are labelled with the numbers of the ports they serve. Each connector can be attached to a fantail that provides four I/O ports.)

Figure 4-1 : Interface jumpers on the low-speed access card. The card shown is configured to provide RS-449/X.21 interfaces for ports 4 - 7 and V.35 interfaces for ports 0 - 3.

Setting CEMAC Interface Jumpers

This section describes the user-settable jumpers on the E1 circuit emulation access card (E1 CEMAC) and shows how to set them.

The jumpers allow you to select termination impedance and grounding on the receive line and the pulse amplitude and grounding on the transmit line. There are two possible settings: use one if you plan to attach the CEMAC to a fantail, and use the other if you plan to use the CEMAC without a fantail. The jumper settings are described below.

Settings for Use with a Fantail

If you plan to use a fantail (which provides 75-ohm interfaces), you must use the 75-ohm settings for termination impedance and pulse amplitude, and set grounding to on.

Settings for Use without a Fantail

If you don't plan to use a fantail, use the default setting, which are as follows: the termination impedance and pulse amplitude jumpers are set to 120 ohms and the transmit and receive lines are not grounded.

Figure 4-2 shows the eight sets of interface jumpers on the card, and illustrates how to set them. (The settings are indicated on the card, as shown.)

The interface jumpers are labelled E1 through E32. The jumpers associated with each port are shown in Table 4-1.

Table 4-1 : E1 CEMAC Jumpers

Jumper	E Number
Function	Port 0	Port 1	Port 2	Port 3	Port 4	Port 5	Port 6	Port 7
Receive Gnd	E29	E25	E21	E17	E13	E9	E5	E1
Impedance	E30	E26	E22	E18	E14	E10	E6	E2
Amplitude	E31	E27	E23	E19	E15	E11	E7	E3
Transmit Gnd	E32	E28	E24	E20	E16	E12	E8	E4

Figure 4-2 : Interface jumpers on the E1 CEMAC. The card shown is configured to the factory default setting.

Turning Off the Transmit Laser on the OC3AC

Single-mode ports on the OC-3c access card have transmit lasers whose emissions can be dangerous to the eye. When a single-mode port is not being used, we recommend that you turn off its transmit laser. Turning off the laser turns on the port's green Safe LED. (When the LED is on, you know that it's safe to look at the connector for that port.)

Warning Do not look directly into the connectors on a single mode OC-3c access card whose Safe LED is turned off. The transmit laser can damage your eyes.

The toggle switch has two positions:

• One switch position turns the port's transmit laser off and turns the green Safe LED on.
  

• The other switch position turns the port's transmit laser on and turns the Safe LED off.
  

To turn off the laser, move the toggle switch, shown in Figure 4-3. The green Safe LED comes on to tell you the laser is off.

Caution If you turn off the transmit laser while the port is passing traffic, the flow of traffic halts.

Figure 4-3 : Detail of single mode OC-3c card's bulkhead showing Safe LED and transmit laser's toggle switch.

Setting Jumpers and Switches on Fantails

This section explains how to set jumpers and switches on LightStream 2020 fantails. It includes these procedures:

• "Setting Ground Jumpers on the E1 Fantail"
  

• "Configuring X.21 Ports as DTE or DCE"
  

Setting Ground Jumpers on the E1 Fantail

The E1 fantail has two jumper positions for each port, as shown in Figure 4-4:

• transmit ground (TX GND) -- the default setting
  

• receive ground (RX GND)
  

The transmit ground jumper setting is appropriate for most applications. If you wish to change the setting to receive ground, you can do so on a per-port basis (that is, the ports can have different settings). To change a port's ground setting from transmit to receive, do this:

Step 1 Remove the jumper from the TX GND position, as shown in the figure.

Step 2 Place the jumper in the RX GND position for the same port.

Figure 4-4 : Jumpers on the E1 fantail can be set to ground at either transmit (TX) or receive (RX).

Configuring X.21 Ports as DTE or DCE

The X.21 fantail has eight ports, and each can be set to function either as DTE or as DCE. Next to each connector is a pair of slider switches with settings labelled DTE and DCE (see Figure 4-5). The two switches in each pair are linked, so it's impossible to set them to different modes.