Note ¯ 
Lucent recommends that you use the STS-1 Mux board with external clocking. Because the STS-1 signal is synchronous, all clocks in the system have the same constant frequency. The STS-1 rate remains at 51.84Mbps, allowing many synchronous STS-1 signals to be stacked together when multiplexed.
Note ¯ 
Because the STS-1 Mux board is hot-swappable you can install an STS-1 Mux board while the PortMaster 4 is turned on and running.
Warning ¯ 
To avoid damaging the internal components of the PortMaster 4, follow antistatic precautions by wearing a grounding wrist strap. See "Grounding Wrist Strap Instructions" on page 2-3.
1. Line up the edge of the STS-1 Mux board with the card guide in slot 0. (Figure 9-1).
Slots are numbered 0 through 9 from left to right. Slot 0 is reserved for the STS-1 Mux board, and slot 4 is reserved for the system manager module.
Figure 9-1 Installing an STS-1 Mux Board
2. Insert the STS-1 Mux board in slot 0 and gently guide it into the slot.
If you have trouble sliding the board into the card guide, gently move it back and forth to help it slide in.
3. When the board is completely inserted in slot 0, close the top and bottom brackets so they are flush with the face of the chassis.
Closing the tabs causes the board to connect with the backplane.
4. After you finish installing boards or modules in the PortMaster 4, ensure that every slot contains either a working board or blank board.
Note ¯ 
This procedure does not cover instructions for provisioning the switch or the data networks to support the PortMaster 4. For more specific information on how to provision your data network or switch, contact your telecommunications service provider.
o Two BNC shielded coaxial cable connectors with 74-ohm impedance and BNC-to-BNC connections on each end. (See "STS-1 Mux Board Physical Specifications" on page 9-8 for more information.)
1. Remove the cover from the cable guide, if necessary.
2. Run the cable through the cable guide duct until it is directly over the STS--1 Mux board.
3. Pull the cable through the fingers of the cable guide duct as shown in Figure 9-2.
Figure 9-2 Pulling a Cable through the Cable Guide
4. Connect the coaxial cables to the BNC connectors of the STS-1 Mux board.
5. Connect the other end of the BNC connectors to the STS-1 BNC connections on the STS-1 circuit source equipment.
Each STS-1 cable connection consists of one transmit line and one receive line. See Figure 9-3 for connector locations, LED status indicators, and a view of the motherboard.
The term circuit source equipment refers to a Digital Network Unit SONET (DNU-S) or a digital cross-connect for DS-1 signals (DSX-1).
Most installations of the STS-1 board require that the cable lines connect the transmit port of the STS-1 Mux board to the receive port of the circuit source equipment, and the receive port of the STS-1 Mux board to the transmit port of the circuit source equipment.
6. Verify the following LED behavior:
a. The PWR LED at the bottom of the board is solidly lit.
b. The amber DIAG LED at the bottom of the board blinks three times per second during startup and then stays solidly lit with a 1-second interruption every 5 seconds.
DIAG LED behavior might vary according to the version of ComOS you are running.
c. The green FAIL LED is not lit.
See "Troubleshooting LED Behavior on an STS-1 Mux Board" on page 9-7 if any LED fails to behave properly.
7. If you have finished inserting boards and connecting lines, replace the cable guide cover by squeezing the duct fingers together with one hand, and sliding the cover over the duct fingers with the other.
Note ¯ 
To activate the STS-1 Mux board, you must first configure Ether0 or Ether1 with an IP address.
| The green LINK LED is lit with no line connection. | Possible hardware failure. | Contact Lucent Technical Support. |
| All LEDs fail to light. | Power is not present. | Check to make sure the power switch is turned on, the power cable is connected, the boards are properly seated, and the fuse functions. For instructions on checking and changing the fuse, see "Replacing a Fuse" on page 4-10. If unable to diagnose contact Lucent Technical Support. |
| Amber DIAG LED on a STS-1 Mux board does not light. | STS-1 Mux board malfunction. | Contact Lucent Technical Support. |
| During startup, the DIAG LED on an STS-1 Mux board fails to light, stays lit, or blinks three times per second continuously. | A hardware problem has occurred. | Contact Lucent Technical Support. |
| During operation, the DIAG LED on an STS-1 Mux board stays solidly lit or does not light. | A hardware problem might have been caused by an external device. | If the LED stays solidly lit or does not light after you have removed all external devices, contact Lucent Technical Support. |
| The amber LOOPBACK LED is lit. | The STS-1 line is in loopback. | If the loopback setting is in error, use the set mux line-loop off command to clear the loopback. See the PortMaster 4 Command Line Reference for more information. |
| The green FAIL LED is lit. | No line is connected. | Check that the cables are securely fastened to the ports. |
| The amber LINK LED is not lit. | There is no STS-1 link. | Verify all switch connections and provisioning. This behavior might indicate a non functioning line. Contact the telephone company. |
| An undefined problem occurred at startup, but the cause cannot be determined from LED behavior. | Refer to the solution column. | Try booting in console mode, and observe the boot messages. See "Observing Boot Messages" on page 4-3. If the boot messages do not suggest a solution, record the information and contact Lucent Technical Support. |
STS-1 Mux Board