|
|
This chapter provides basic installation troubleshooting information. The chapter includes the following sections:
 |
Note This chapter provides only hardware troubleshooting information---it does not require access to the Cisco IOS command-line interface (CLI) or knowledge of CLI commands. For information on troubleshooting the software configuration, see the Cisco uBR910 Cable DSU Software Configuration Guide. |
Installation problems with Cisco uBR910 series DSUs are commonly due to one of the following:
The LEDs on the front and back panels display the current operational status and help you determine problem areas. For more information on these LEDs, see "Product Overview."
|
Note Problems will also occur if the configuration of the routing and serial interface parameters on the access router and Cisco uBR910 series DSU do not match. See the Cisco uBR910 Cable DSU Software Configuration Guide for more information on those parameters. |
When the Cisco uBR910 series DSU first powers on, it performs the following self-test and initialization routines:
1. Applying power immediately turns the PWR LED on; the RPS LED also turns on if the RPS adapter plate is properly installed and connected to the Cisco RPS.
2. The primary ROM monitor in Flash memory tests the secondary ROM monitor. If the secondary ROM monitor is present in Flash memory and passes its verification tests, it assumes control and continues with the initialization process; otherwise, the primary ROM monitor continues with the initialization process.
3. The system runs its diagnostic procedures. These procedures ensure that all basic components are functioning. To complete all of the diagnostic procedures, the Cisco uBR910 series processor must be able to:
4. The next step of the self-test is to initialize the memory controller and its Dynamic Random Access Memory (DRAM). If this step succeeds, the PWR, RPS, DS, and DSNR LEDs turn on.
5. The console port is initialized and the banner is output to the console port.
6. Next, the Cisco uBR910 series performs a self-test on the low registers of the DRAM. When this test starts, all LEDS turn off and the CBL LNK, US, and PWR LEDs are turned on.
7. The next step tests the BSS uninitialized data area of the DRAM. When this test starts, all LEDs turn off and the CBL LNK, US, DSNR, and PWR LEDs turn on. If this test succeeds, the CBL LNK LED turns off, and the US, DSNR, and PWR LEDs remain on.
8. The final step tests the remaining DRAM. When this test starts, all LEDS turn off and the DS, US, and PWR LEDs are turned on. If this test succeeds, the US LED turns off and the DS and PWR LEDs remain on.
9. If all self-tests passed, the Cisco uBR910 series turns off all LEDs except PWR and boots the Cisco IOS image stored in its Flash memory. The Activity LED blinks during the boot process. If the Activity LED does not start to blink, see the "Power Subsystem" troubleshooting section.
10. If the Cisco IOS image booted successfully, it takes control from the ROM monitor code and turns the Activity LED on solid.
11. After the Cisco IOS image starts, the Cisco uBR910 series begins the DOCSIS provisioning process. At this point, the US, DSNR, SER LINK, and CBL LINK LEDs indicate whether the system is operational and connected to both the cable network and subscriber LAN:
|
Note Because the signal-to-noise ratio and lock threshold can drift, they are regularly checked and the DSNR LED is updated. While this might cause the DSNR LED to occasionally blink briefly, under normal conditions the DSNR LED should remain on. |
12. When the Cisco uBR910 series DSU has successfully initialized, users on the local area network should be able to access the connected network. If not, then from a PC on the subscriber LAN, try to ping the IP address for the Ethernet interface on the access router. If this is not successful, check the local Ethernet cabling and the configuration of the access router's Ethernet interface.
13. If you can ping the access router's Ethernet interface, next try to ping the IP address for the access router's serial interface that is connected to the Cisco uBR910 series DSU. If this is not successful, check the configuration of the access router's serial interface and that the access router is configured to bridge or route traffic between its Ethernet and serial interfaces.
14. If you can ping the access router's serial interface, next try to ping the IP address for the Cisco uBR910 series DSU's serial interface (if in routing mode) or cable interface (if in bridging mode). If this is not successful, troubleshoot the Cisco uBR910 series DSU subsystem as follows:
The key to troubleshooting is to isolate a problem to a specific subsystem:
Figure 4-1 on the next page provides a general troubleshooting flowchart. Table 4-1 helps you correlate LED behavior with possible problems, and suggested courses of actions.
| LED | Status | Possible Problem | Suggested Action | ||
|---|---|---|---|---|---|
Power
| Power LED is off. | Power is not being supplied. Power cord not properly seated. Power outlet not operating. Power supply has failed. | Check power connections. If using the RPS, check that the RPS adapter plate is correctly installed and connected. Check power connections. Check the outlet. Contact field service dispatch to replace the power supply. | ||
The unit failed its self-test. | Contact field service dispatch to replace the unit. | ||||
RPS | RPS LED is off. | The RPS adapter plate is not installed or is not connected to the RPS. | Check the connections between the RPS and the RPS adapter plate. See the documentation that accompanied the RPS adapter plate kit for details. | ||
|
Cable RF LED is blinking. | Cisco uBR910 series searching for a signal; RF levels wrong. Cable is out. | Check for a DOCSIS system signal and verify the nearby analog video signal is within the correct range---0 to +15 dBmV for most CATV systems. Check if the cable TV is working if the subscriber also subscribes to broadcast TV services.
| |||
DS | RF coaxial cable is not properly connected to the F-connector on the rear panel. | Reconnect the cable. | |||
US | Upstream signal is not reaching the headend; Cisco uBR910 series is unable to communicate with the remote end. Systematic RF noise problem or other outage. | Verify continuity back to the headend using the standard procedures for your system. Temporarily locate the Cisco uBR910 series closer to the ground block, the tap, or another tap closer to the headend---ensuring correct RF input level at all times. | |||
DSNR | Systematic RF noise problem or other outage. | Verify correct RF input to the Cisco uBR910 series. Temporarily locate the chassis closer to the ground block, the tap, or another tap closer to the headend---ensuring correct RF input level at all times.
|
To help isolate a problem with the Cisco uBR910 series power subsystem, look at the Activity and Power LEDs. Do the LEDs remain on when self-test is completed and a software image booted?
|
Note If you are unable to resolve the problem or you determine that either a power supply or Cisco uBR910 series connector is faulty, contact your field office for instructions. |
For proper operation the Cisco uBR910 series DSU must be able to establish a connection with the service provider's CMTS. There are many conditions inherent to coaxial cable that can inhibit this connection.
If the TV does not receive any cable channels, contact the service provider to re-establish service to the site. If the TV does receive cable channels, it indicates that the basic infrastructure between the site and the HFC plant and headend is working; however, because data connections are much more sensitive to signal interference than cable TV service, it is still possible that a problem exists that prevents reception of the data signals.
Step 2 If you are using a splitter or couple to share the coaxial cable between a TV and the Cisco uBR910 series DSU, remove the splitter/coupler, TV, and any other devices connected to the cable (such as video players) so that the Cisco uBR910 series connects directly to the coaxial cable coming out of the CATV wall outlet. Make sure the Cisco uBR910 series is the only device on this segment of cable.
If the Cisco uBR910 series functions in this configuration, inspect the splitter and any other devices that were installed on this cable segment. If necessary, upgrade them and their interconnecting cables with ones that have higher-quality connectors---see the "Coaxial Connector and Cable Specifications" section for the recommended cable and connector quality. If this does not help, you might need to install a separate cable for TV reception.
Step 3 Disconnect the coaxial cable from the F-connector on the rear panel and inspect the cable and its connector. Is the center conductor on the coaxial cable end straight and of the correct length to ensure a good connection?
If the center conductor is not straight or appears to be too long or too short, cut the coaxial cable behind the connector end, and strip the insulation back. Make sure that the newly exposed center conductor is straight. Before replacing the new cable connector end, check the general condition of the cable. Make sure the new conductor end is securely crimped to the cable.
|
Note The center connector should extend 1/8 inch (3.2 mm) beyond the end of the connector. |
Step 4 Is the coaxial cable in excellent condition?
The coaxial cable between the Cisco uBR910 series and the cable tap must be very high quality. The cable insulation must be at least 80% braid with foil. If the existing cable appears to be of lesser quality or in poor condition, replace the cable from the ground block or tap to the cable end.
Step 5 Is the coaxial cable connection to the back of the unit secure?
Check that the coaxial cable end is securely screwed onto the F-connector at the back of the Cisco uBR910 series. Hand-tighten the connector, making sure it is finger tight; then give it a 1/6 turn.
|
Note If you are unable to resolve the problem, contact your internal service organization for instructions and assistance. |
The use of RF and digital signals on the same cable can lead to interference if the HFC network is not correctly configured.
The Cisco uBR910 series DSU connects to the subscriber LAN through its serial interface to the LAN access router. If PCs or routers on the subscriber LAN cannot access the cable network, check for the following:
Step 2 If you suspect that data is not being passed over the serial link, access the CLI to check the configuration of the serial ports on the Cisco uBR910 series DSU and access router. In particular, check the following:
If the above do not correct the problem, check the configuration of the serial interfaces on both the Cisco uBR910 series DSU and access router. See the Cisco uBR910 Cable DSU Software Configuration Guide for details.
The Cisco uBR910 series chassis contains a reset switch with three different actions:
See Table 4-2 for additional information.
| Type of Reset | Press Reset Switch... | What Happens... |
|---|---|---|
Warm | Less than 10 seconds | The Cisco uBR910 series reboots, using the downstream frequencies saved in the configuration file. |
Cold | 10 to 29 seconds | The Cisco uBR910 series reboots the image in flash memory, ignoring the downstream frequencies saved in the configuration file. The Cisco uBR910 series initiates a downstream frequency search which may take a few minutes. The new frequencies are saved in the configuration file and are used at the next warm reset. |
Cold | More than 30 seconds | The Cisco uBR910 series downloads a new image from the CMTS and reboots, storing this image in Flash memory (this assumes coordination between the CMTS system administrator and field personnel). |
|
Note The reset switch on the back panel of the Cisco uBR910 series DSU is recessed to prevent accidental resets of the router. To depress the switch, use a blunt object, such as a pen or pencil point; do not use a sharp object, such as a knife or awl, because this could permanently damage the switch and the router's circuitry. |
If you experience trouble with the startup that is not resolved with the procedures and tips in this chapter, contact field service dispatch for further assistance and instructions.
|
Note Cisco recommends that a CMTS systems engineer or network administrator be available, or on-call, to assist field service technicians or installers in troubleshooting a Cisco uBR910 series DSU. If you are a network administrator or systems engineer with a Cisco product covered under warranty or a maintenance contract, contact Cisco's Technical Assistance Center (TAC) at 800 553-2447, 408 526-7209, or tac@cisco.com. |
Posted: Wed Jun 21 11:41:16 PDT 2000
Copyright 1989 - 2000©Cisco Systems Inc.